Literature Review vs Systematic Review

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It’s common to confuse systematic and literature reviews because both are used to provide a summary of the existent literature or research on a specific topic. Regardless of this commonality, both types of review vary significantly. The following table provides a detailed explanation as well as the differences between systematic and literature reviews. 

Kysh, Lynn (2013): Difference between a systematic review and a literature review. [figshare]. Available at:  http://dx.doi.org/10.6084/m9.figshare.766364

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As a researcher, you may be required to conduct a literature review. But what kind of review do you need to complete? Is it a systematic literature review or a standard literature review? In this article, we’ll outline the purpose of a systematic literature review, the difference between literature review and systematic review, and other important aspects of systematic literature reviews.

What is a Systematic Literature Review?

The purpose of systematic literature reviews is simple. Essentially, it is to provide a high-level of a particular research question. This question, in and of itself, is highly focused to match the review of the literature related to the topic at hand. For example, a focused question related to medical or clinical outcomes.

The components of a systematic literature review are quite different from the standard literature review research theses that most of us are used to (more on this below). And because of the specificity of the research question, typically a systematic literature review involves more than one primary author. There’s more work related to a systematic literature review, so it makes sense to divide the work among two or three (or even more) researchers.

Your systematic literature review will follow very clear and defined protocols that are decided on prior to any review. This involves extensive planning, and a deliberately designed search strategy that is in tune with the specific research question. Every aspect of a systematic literature review, including the research protocols, which databases are used, and dates of each search, must be transparent so that other researchers can be assured that the systematic literature review is comprehensive and focused.

Most systematic literature reviews originated in the world of medicine science. Now, they also include any evidence-based research questions. In addition to the focus and transparency of these types of reviews, additional aspects of a quality systematic literature review includes:

  • Clear and concise review and summary
  • Comprehensive coverage of the topic
  • Accessibility and equality of the research reviewed

Systematic Review vs Literature Review

The difference between literature review and systematic review comes back to the initial research question. Whereas the systematic review is very specific and focused, the standard literature review is much more general. The components of a literature review, for example, are similar to any other research paper. That is, it includes an introduction, description of the methods used, a discussion and conclusion, as well as a reference list or bibliography.

A systematic review, however, includes entirely different components that reflect the specificity of its research question, and the requirement for transparency and inclusion. For instance, the systematic review will include:

  • Eligibility criteria for included research
  • A description of the systematic research search strategy
  • An assessment of the validity of reviewed research
  • Interpretations of the results of research included in the review

As you can see, contrary to the general overview or summary of a topic, the systematic literature review includes much more detail and work to compile than a standard literature review. Indeed, it can take years to conduct and write a systematic literature review. But the information that practitioners and other researchers can glean from a systematic literature review is, by its very nature, exceptionally valuable.

This is not to diminish the value of the standard literature review. The importance of literature reviews in research writing is discussed in this article . It’s just that the two types of research reviews answer different questions, and, therefore, have different purposes and roles in the world of research and evidence-based writing.

Systematic Literature Review vs Meta Analysis

It would be understandable to think that a systematic literature review is similar to a meta analysis. But, whereas a systematic review can include several research studies to answer a specific question, typically a meta analysis includes a comparison of different studies to suss out any inconsistencies or discrepancies. For more about this topic, check out Systematic Review VS Meta-Analysis article.

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The difference between a systematic review and a literature review

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Covidence takes a look at the difference between the two

Most of us are familiar with the terms systematic review and literature review. Both review types synthesise evidence and provide summary information. So what are the differences? What does systematic mean? And which approach is best 🤔 ?

‘ Systematic ‘ describes the review’s methods. It means that they are transparent, reproducible and defined before the search gets underway. That’s important because it helps to minimise the bias that would result from cherry-picking studies in a non-systematic way. 

This brings us to literature reviews. Literature reviews don’t usually apply the same rigour in their methods. That’s because, unlike systematic reviews, they don’t aim to produce an answer to a clinical question. Literature reviews can provide context or background information for a new piece of research. They can also stand alone as a general guide to what is already known about a particular topic. 

Interest in systematic reviews has grown in recent years and the frequency of ‘systematic reviews’ in Google books has overtaken ‘literature reviews’ (with all the usual Ngram Viewer warnings – it searches around 6% of all books, no journals). 

difference between a literature review and systematic review

Let’s take a look at the two review types in more detail to highlight some key similarities and differences 👀.

🙋🏾‍♂️ What is a systematic review?

Systematic reviews ask a specific question about the effectiveness of a treatment and answer it by summarising evidence that meets a set of pre-specified criteria. 

The process starts with a research question and a protocol or research plan. A review team searches for studies to answer the question using a highly sensitive search strategy. The retrieved studies are then screened for eligibility using the inclusion and exclusion criteria (this is done by at least two people working independently). Next, the reviewers extract the relevant data and assess the quality of the included studies. Finally, the review team synthesises the extracted study data and presents the results. The process is shown in figure 2 .

difference between a literature review and systematic review

The results of a systematic review can be presented in many ways and the choice will depend on factors such as the type of data. Some reviews use meta-analysis to produce a statistical summary of effect estimates. Other reviews use narrative synthesis to present a textual summary.

Covidence accelerates the screening, data extraction, and quality assessment stages of your systematic review. It provides simple workflows and easy collaboration with colleagues around the world.

When is it appropriate to do a systematic review?

If you have a clinical question about the effectiveness of a particular treatment or treatments, you could answer it by conducting a systematic review. Systematic reviews in clinical medicine often follow the PICO framework, which stands for:

👦 Population (or patients)

💊 Intervention

💊 Comparison

Here’s a typical example of a systematic review title that uses the PICO framework: Alarms [intervention] versus drug treatments [comparison] for the prevention of nocturnal enuresis [outcome] in children [population]

Key attributes

  • Systematic reviews follow prespecified methods
  • The methods are explicit and replicable
  • The review team assesses the quality of the evidence and attempts to minimise bias
  • Results and conclusions are based on the evidence

🙋🏻‍♀️ What is a literature review?

Literature reviews provide an overview of what is known about a particular topic. They evaluate the material, rather than simply restating it, but the methods used to do this are not usually prespecified and they are not described in detail in the review. The search might be comprehensive but it does not aim to be exhaustive. Literature reviews are also referred to as narrative reviews.

Literature reviews use a topical approach and often take the form of a discussion. Precision and replicability are not the focus, rather the author seeks to demonstrate their understanding and perhaps also present their work in the context of what has come before. Often, this sort of synthesis does not attempt to control for the author’s own bias. The results or conclusion of a literature review is likely to be presented using words rather than statistical methods.

When is it appropriate to do a literature review?

We’ve all written some form of literature review: they are a central part of academic research ✍🏾. Literature reviews often form the introduction to a piece of writing, to provide the context. They can also be used to identify gaps in the literature and the need to fill them with new research 📚.

  • Literature reviews take a thematic approach
  • They do not specify inclusion or exclusion criteria
  • They do not answer a clinical question
  • The conclusions might be influenced by the author’s own views

🙋🏽 Ok, but what is a systematic literature review?

A quick internet search retrieves a cool 200 million hits for ‘systematic literature review’. What strange hybrid is this 🤯🤯 ?

Systematic review methodology has its roots in evidence-based medicine but it quickly gained traction in other areas – the social sciences for example – where researchers recognise the value of being methodical and minimising bias. Systematic review methods are increasingly applied to the more traditional types of review, including literature reviews, hence the proliferation of terms like ‘systematic literature review’ and many more.

Beware of the labels 🚨. The terminology used to describe review types can vary by discipline and changes over time. To really understand how any review was done you will need to examine the methods critically and make your own assessment of the quality and reliability of each synthesis 🤓.

Review methods are evolving constantly as researchers find new ways to meet the challenge of synthesising the evidence. Systematic review methods have influenced many other review types, including the traditional literature review. 

Covidence is a web-based tool that saves you time at the screening, selection, data extraction and quality assessment stages of your systematic review. It supports easy collaboration across teams and provides a clear overview of task status.

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Laura Mellor. Portsmouth, UK

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Know the Difference! Systematic Review vs. Literature Review

It is common to confuse systematic and literature reviews as both are used to provide a summary of the existent literature or research on a specific topic.  Even with this common ground, both types vary significantly.  Please review the following chart (and its corresponding poster linked below) for the detailed explanation of each as well as the differences between each type of review.

  • What's in a name? The difference between a Systematic Review and a Literature Review, and why it matters by Lynn Kysh, MLIS, University of Southern California - Norris Medical Library
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Difference Between Literature Review and Systematic Review

Main difference – literature review vs systematic review.

Literature review and systematic review are two scholarly texts that help to introduce new knowledge to various fields. A literature review, which reviews the existing research and information on a selected study area, is a crucial element of a research study. A systematic review is also a type of a literature review. The main difference between literature review and systematic review is their focus on the research question ; a systematic review is focused on a specific research question whereas a literature review is not.

This article highlights,

1. What is a Literature Review?        – Definition, Features, Characteristics

2. What is a Systematic Review?        – Definition, Features, Characteristics

Difference Between Literature Review and Systematic Review - Comparison Summary

What is a Literature Review

A literature review is an indispensable element of a research study. This is where the researcher shows his knowledge on the subject area he or she is researching on. A literature review is a discussion on the already existing material in the subject area. Thus, this will require a collection of published (in print or online) work concerning the selected research area. In simple terms, a literature is a review of the literature in the related subject area.

A good literature review is a critical discussion, displaying the writer’s knowledge on relevant theories and approaches and awareness of contrasting arguments. A literature review should have the following features (Caulley, 1992)

  • Compare and contrast different researchers’ views
  • Identify areas in which researchers are in disagreement
  • Group researchers who have similar conclusions
  • Criticize the methodology
  • Highlight exemplary studies
  • Highlight gaps in research
  • Indicate the connection between your study and previous studies
  • Indicate how your study will contribute to the literature in general
  • Conclude by summarizing what the literature indicates

The structure of a literature review is similar to that of an article or essay, unlike an annotated bibliography . The information that is collected is integrated into paragraphs based on their relevance. Literature reviews help researchers to evaluate the existing literature, to identify a gap in the research area, to place their study in the existing research and identify future research.

Difference Between Literature Review and Systematic Review

What is a Systematic Review

A systematic review is a type of systematic review that is focused on a particular research question . The main purpose of this type of research is to identify, review, and summarize the best available research on a specific research question. Systematic reviews are used mainly because the review of existing studies is often more convenient than conducting a new study. These are mostly used in the health and medical field, but they are not rare in fields such as social sciences and environmental science.  Given below are the main stages of a systematic review:

  • Defining the research question and identifying an objective method
  • Searching for relevant data that from existing research studies that meet certain criteria (research studies must be reliable and valid).
  • Extracting data from the selected studies (data such as the participants, methods, outcomes, etc.
  • Assessing the quality of information
  • Analyzing and combining all the data which would give an overall result.

Literature Review is a critical evaluation of the existing published work in a selected research area.

Systematic Review is a type of literature review that is focused on a particular research question.

Literature Review aims to review the existing literature, identify the research gap, place the research study in relation to other studies, to evaluate promising research methods, and to suggest further research.

Systematic Review aims to identify, review, and summarize the best available research on a specific research question.

Research Question

In Literature Review, a r esearch question is formed after writing the literature review and identifying the research gap.

In Systematic Review, a research question is formed at the beginning of the systematic review.

Research Study

Literature Review is an essential component of a research study and is done at the beginning of the study.

Systematic Review is not followed by a separate research study.

Caulley, D. N. “Writing a critical review of the literature.”  La Trobe University: Bundoora  (1992).

“Animated Storyboard: What Are Systematic Reviews?” .  cccrg.cochrane.org .  Cochrane Consumers and Communication . Retrieved 1 June 2016.

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What Is a Systematic Review?

Regular literature reviews are simply summaries of the literature on a particular topic. A systematic review, however, is a comprehensive literature review conducted to answer a specific research question. Authors of a systematic review aim to find, code, appraise, and synthesize all of the previous research on their question in an unbiased and well-documented manner. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) outline the minimum amount of information that needs to be reported at the conclusion of a systematic review project. 

Other types of what are known as "evidence syntheses," such as scoping, rapid, and integrative reviews, have varying methodologies. While systematic reviews originated with and continue to be a popular publication type in medicine and other health sciences fields, more and more researchers in other disciplines are choosing to conduct evidence syntheses. 

This guide will walk you through the major steps of a systematic review and point you to key resources including Covidence, a systematic review project management tool. For help with systematic reviews and other major literature review projects, please send us an email at  [email protected] .

Getting Help with Reviews

Organization such as the Institute of Medicine recommend that you consult a librarian when conducting a systematic review. Librarians at the University of Nevada, Reno can help you:

  • Understand best practices for conducting systematic reviews and other evidence syntheses in your discipline
  • Choose and formulate a research question
  • Decide which review type (e.g., systematic, scoping, rapid, etc.) is the best fit for your project
  • Determine what to include and where to register a systematic review protocol
  • Select search terms and develop a search strategy
  • Identify databases and platforms to search
  • Find the full text of articles and other sources
  • Become familiar with free citation management (e.g., EndNote, Zotero)
  • Get access to you and help using Covidence, a systematic review project management tool

Doing a Systematic Review

  • Plan - This is the project planning stage. You and your team will need to develop a good research question, determine the type of review you will conduct (systematic, scoping, rapid, etc.), and establish the inclusion and exclusion criteria (e.g., you're only going to look at studies that use a certain methodology). All of this information needs to be included in your protocol. You'll also need to ensure that the project is viable - has someone already done a systematic review on this topic? Do some searches and check the various protocol registries to find out. 
  • Identify - Next, a comprehensive search of the literature is undertaken to ensure all studies that meet the predetermined criteria are identified. Each research question is different, so the number and types of databases you'll search - as well as other online publication venues - will vary. Some standards and guidelines specify that certain databases (e.g., MEDLINE, EMBASE) should be searched regardless. Your subject librarian can help you select appropriate databases to search and develop search strings for each of those databases.  
  • Evaluate - In this step, retrieved articles are screened and sorted using the predetermined inclusion and exclusion criteria. The risk of bias for each included study is also assessed around this time. It's best if you import search results into a citation management tool (see below) to clean up the citations and remove any duplicates. You can then use a tool like Rayyan (see below) to screen the results. You should begin by screening titles and abstracts only, and then you'll examine the full text of any remaining articles. Each study should be reviewed by a minimum of two people on the project team. 
  • Collect - Each included study is coded and the quantitative or qualitative data contained in these studies is then synthesized. You'll have to either find or develop a coding strategy or form that meets your needs. 
  • Explain - The synthesized results are articulated and contextualized. What do the results mean? How have they answered your research question?
  • Summarize - The final report provides a complete description of the methods and results in a clear, transparent fashion. 

Adapted from

Types of reviews, systematic review.

These types of studies employ a systematic method to analyze and synthesize the results of numerous studies. "Systematic" in this case means following a strict set of steps - as outlined by entities like PRISMA and the Institute of Medicine - so as to make the review more reproducible and less biased. Consistent, thorough documentation is also key. Reviews of this type are not meant to be conducted by an individual but rather a (small) team of researchers. Systematic reviews are widely used in the health sciences, often to find a generalized conclusion from multiple evidence-based studies. 

Meta-Analysis

A systematic method that uses statistics to analyze the data from numerous studies. The researchers combine the data from studies with similar data types and analyze them as a single, expanded dataset. Meta-analyses are a type of systematic review.

Scoping Review

A scoping review employs the systematic review methodology to explore a broader topic or question rather than a specific and answerable one, as is generally the case with a systematic review. Authors of these types of reviews seek to collect and categorize the existing literature so as to identify any gaps.

Rapid Review

Rapid reviews are systematic reviews conducted under a time constraint. Researchers make use of workarounds to complete the review quickly (e.g., only looking at English-language publications), which can lead to a less thorough and more biased review. 

Narrative Review

A traditional literature review that summarizes and synthesizes the findings of numerous original research articles. The purpose and scope of narrative literature reviews vary widely and do not follow a set protocol. Most literature reviews are narrative reviews. 

Umbrella Review

Umbrella reviews are, essentially, systematic reviews of systematic reviews. These compile evidence from multiple review studies into one usable document. 

Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal , vol. 26, no. 2, 2009, pp. 91-108. doi: 10.1111/j.1471-1842.2009.00848.x .

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Systematic Review | Definition, Example & Guide

Published on June 15, 2022 by Shaun Turney . Revised on November 20, 2023.

A systematic review is a type of review that uses repeatable methods to find, select, and synthesize all available evidence. It answers a clearly formulated research question and explicitly states the methods used to arrive at the answer.

They answered the question “What is the effectiveness of probiotics in reducing eczema symptoms and improving quality of life in patients with eczema?”

In this context, a probiotic is a health product that contains live microorganisms and is taken by mouth. Eczema is a common skin condition that causes red, itchy skin.

Table of contents

What is a systematic review, systematic review vs. meta-analysis, systematic review vs. literature review, systematic review vs. scoping review, when to conduct a systematic review, pros and cons of systematic reviews, step-by-step example of a systematic review, other interesting articles, frequently asked questions about systematic reviews.

A review is an overview of the research that’s already been completed on a topic.

What makes a systematic review different from other types of reviews is that the research methods are designed to reduce bias . The methods are repeatable, and the approach is formal and systematic:

  • Formulate a research question
  • Develop a protocol
  • Search for all relevant studies
  • Apply the selection criteria
  • Extract the data
  • Synthesize the data
  • Write and publish a report

Although multiple sets of guidelines exist, the Cochrane Handbook for Systematic Reviews is among the most widely used. It provides detailed guidelines on how to complete each step of the systematic review process.

Systematic reviews are most commonly used in medical and public health research, but they can also be found in other disciplines.

Systematic reviews typically answer their research question by synthesizing all available evidence and evaluating the quality of the evidence. Synthesizing means bringing together different information to tell a single, cohesive story. The synthesis can be narrative ( qualitative ), quantitative , or both.

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difference between a literature review and systematic review

Systematic reviews often quantitatively synthesize the evidence using a meta-analysis . A meta-analysis is a statistical analysis, not a type of review.

A meta-analysis is a technique to synthesize results from multiple studies. It’s a statistical analysis that combines the results of two or more studies, usually to estimate an effect size .

A literature review is a type of review that uses a less systematic and formal approach than a systematic review. Typically, an expert in a topic will qualitatively summarize and evaluate previous work, without using a formal, explicit method.

Although literature reviews are often less time-consuming and can be insightful or helpful, they have a higher risk of bias and are less transparent than systematic reviews.

Similar to a systematic review, a scoping review is a type of review that tries to minimize bias by using transparent and repeatable methods.

However, a scoping review isn’t a type of systematic review. The most important difference is the goal: rather than answering a specific question, a scoping review explores a topic. The researcher tries to identify the main concepts, theories, and evidence, as well as gaps in the current research.

Sometimes scoping reviews are an exploratory preparation step for a systematic review, and sometimes they are a standalone project.

A systematic review is a good choice of review if you want to answer a question about the effectiveness of an intervention , such as a medical treatment.

To conduct a systematic review, you’ll need the following:

  • A precise question , usually about the effectiveness of an intervention. The question needs to be about a topic that’s previously been studied by multiple researchers. If there’s no previous research, there’s nothing to review.
  • If you’re doing a systematic review on your own (e.g., for a research paper or thesis ), you should take appropriate measures to ensure the validity and reliability of your research.
  • Access to databases and journal archives. Often, your educational institution provides you with access.
  • Time. A professional systematic review is a time-consuming process: it will take the lead author about six months of full-time work. If you’re a student, you should narrow the scope of your systematic review and stick to a tight schedule.
  • Bibliographic, word-processing, spreadsheet, and statistical software . For example, you could use EndNote, Microsoft Word, Excel, and SPSS.

A systematic review has many pros .

  • They minimize research bias by considering all available evidence and evaluating each study for bias.
  • Their methods are transparent , so they can be scrutinized by others.
  • They’re thorough : they summarize all available evidence.
  • They can be replicated and updated by others.

Systematic reviews also have a few cons .

  • They’re time-consuming .
  • They’re narrow in scope : they only answer the precise research question.

The 7 steps for conducting a systematic review are explained with an example.

Step 1: Formulate a research question

Formulating the research question is probably the most important step of a systematic review. A clear research question will:

  • Allow you to more effectively communicate your research to other researchers and practitioners
  • Guide your decisions as you plan and conduct your systematic review

A good research question for a systematic review has four components, which you can remember with the acronym PICO :

  • Population(s) or problem(s)
  • Intervention(s)
  • Comparison(s)

You can rearrange these four components to write your research question:

  • What is the effectiveness of I versus C for O in P ?

Sometimes, you may want to include a fifth component, the type of study design . In this case, the acronym is PICOT .

  • Type of study design(s)
  • The population of patients with eczema
  • The intervention of probiotics
  • In comparison to no treatment, placebo , or non-probiotic treatment
  • The outcome of changes in participant-, parent-, and doctor-rated symptoms of eczema and quality of life
  • Randomized control trials, a type of study design

Their research question was:

  • What is the effectiveness of probiotics versus no treatment, a placebo, or a non-probiotic treatment for reducing eczema symptoms and improving quality of life in patients with eczema?

Step 2: Develop a protocol

A protocol is a document that contains your research plan for the systematic review. This is an important step because having a plan allows you to work more efficiently and reduces bias.

Your protocol should include the following components:

  • Background information : Provide the context of the research question, including why it’s important.
  • Research objective (s) : Rephrase your research question as an objective.
  • Selection criteria: State how you’ll decide which studies to include or exclude from your review.
  • Search strategy: Discuss your plan for finding studies.
  • Analysis: Explain what information you’ll collect from the studies and how you’ll synthesize the data.

If you’re a professional seeking to publish your review, it’s a good idea to bring together an advisory committee . This is a group of about six people who have experience in the topic you’re researching. They can help you make decisions about your protocol.

It’s highly recommended to register your protocol. Registering your protocol means submitting it to a database such as PROSPERO or ClinicalTrials.gov .

Step 3: Search for all relevant studies

Searching for relevant studies is the most time-consuming step of a systematic review.

To reduce bias, it’s important to search for relevant studies very thoroughly. Your strategy will depend on your field and your research question, but sources generally fall into these four categories:

  • Databases: Search multiple databases of peer-reviewed literature, such as PubMed or Scopus . Think carefully about how to phrase your search terms and include multiple synonyms of each word. Use Boolean operators if relevant.
  • Handsearching: In addition to searching the primary sources using databases, you’ll also need to search manually. One strategy is to scan relevant journals or conference proceedings. Another strategy is to scan the reference lists of relevant studies.
  • Gray literature: Gray literature includes documents produced by governments, universities, and other institutions that aren’t published by traditional publishers. Graduate student theses are an important type of gray literature, which you can search using the Networked Digital Library of Theses and Dissertations (NDLTD) . In medicine, clinical trial registries are another important type of gray literature.
  • Experts: Contact experts in the field to ask if they have unpublished studies that should be included in your review.

At this stage of your review, you won’t read the articles yet. Simply save any potentially relevant citations using bibliographic software, such as Scribbr’s APA or MLA Generator .

  • Databases: EMBASE, PsycINFO, AMED, LILACS, and ISI Web of Science
  • Handsearch: Conference proceedings and reference lists of articles
  • Gray literature: The Cochrane Library, the metaRegister of Controlled Trials, and the Ongoing Skin Trials Register
  • Experts: Authors of unpublished registered trials, pharmaceutical companies, and manufacturers of probiotics

Step 4: Apply the selection criteria

Applying the selection criteria is a three-person job. Two of you will independently read the studies and decide which to include in your review based on the selection criteria you established in your protocol . The third person’s job is to break any ties.

To increase inter-rater reliability , ensure that everyone thoroughly understands the selection criteria before you begin.

If you’re writing a systematic review as a student for an assignment, you might not have a team. In this case, you’ll have to apply the selection criteria on your own; you can mention this as a limitation in your paper’s discussion.

You should apply the selection criteria in two phases:

  • Based on the titles and abstracts : Decide whether each article potentially meets the selection criteria based on the information provided in the abstracts.
  • Based on the full texts: Download the articles that weren’t excluded during the first phase. If an article isn’t available online or through your library, you may need to contact the authors to ask for a copy. Read the articles and decide which articles meet the selection criteria.

It’s very important to keep a meticulous record of why you included or excluded each article. When the selection process is complete, you can summarize what you did using a PRISMA flow diagram .

Next, Boyle and colleagues found the full texts for each of the remaining studies. Boyle and Tang read through the articles to decide if any more studies needed to be excluded based on the selection criteria.

When Boyle and Tang disagreed about whether a study should be excluded, they discussed it with Varigos until the three researchers came to an agreement.

Step 5: Extract the data

Extracting the data means collecting information from the selected studies in a systematic way. There are two types of information you need to collect from each study:

  • Information about the study’s methods and results . The exact information will depend on your research question, but it might include the year, study design , sample size, context, research findings , and conclusions. If any data are missing, you’ll need to contact the study’s authors.
  • Your judgment of the quality of the evidence, including risk of bias .

You should collect this information using forms. You can find sample forms in The Registry of Methods and Tools for Evidence-Informed Decision Making and the Grading of Recommendations, Assessment, Development and Evaluations Working Group .

Extracting the data is also a three-person job. Two people should do this step independently, and the third person will resolve any disagreements.

They also collected data about possible sources of bias, such as how the study participants were randomized into the control and treatment groups.

Step 6: Synthesize the data

Synthesizing the data means bringing together the information you collected into a single, cohesive story. There are two main approaches to synthesizing the data:

  • Narrative ( qualitative ): Summarize the information in words. You’ll need to discuss the studies and assess their overall quality.
  • Quantitative : Use statistical methods to summarize and compare data from different studies. The most common quantitative approach is a meta-analysis , which allows you to combine results from multiple studies into a summary result.

Generally, you should use both approaches together whenever possible. If you don’t have enough data, or the data from different studies aren’t comparable, then you can take just a narrative approach. However, you should justify why a quantitative approach wasn’t possible.

Boyle and colleagues also divided the studies into subgroups, such as studies about babies, children, and adults, and analyzed the effect sizes within each group.

Step 7: Write and publish a report

The purpose of writing a systematic review article is to share the answer to your research question and explain how you arrived at this answer.

Your article should include the following sections:

  • Abstract : A summary of the review
  • Introduction : Including the rationale and objectives
  • Methods : Including the selection criteria, search method, data extraction method, and synthesis method
  • Results : Including results of the search and selection process, study characteristics, risk of bias in the studies, and synthesis results
  • Discussion : Including interpretation of the results and limitations of the review
  • Conclusion : The answer to your research question and implications for practice, policy, or research

To verify that your report includes everything it needs, you can use the PRISMA checklist .

Once your report is written, you can publish it in a systematic review database, such as the Cochrane Database of Systematic Reviews , and/or in a peer-reviewed journal.

In their report, Boyle and colleagues concluded that probiotics cannot be recommended for reducing eczema symptoms or improving quality of life in patients with eczema. Note Generative AI tools like ChatGPT can be useful at various stages of the writing and research process and can help you to write your systematic review. However, we strongly advise against trying to pass AI-generated text off as your own work.

If you want to know more about statistics , methodology , or research bias , make sure to check out some of our other articles with explanations and examples.

  • Student’s  t -distribution
  • Normal distribution
  • Null and Alternative Hypotheses
  • Chi square tests
  • Confidence interval
  • Quartiles & Quantiles
  • Cluster sampling
  • Stratified sampling
  • Data cleansing
  • Reproducibility vs Replicability
  • Peer review
  • Prospective cohort study

Research bias

  • Implicit bias
  • Cognitive bias
  • Placebo effect
  • Hawthorne effect
  • Hindsight bias
  • Affect heuristic
  • Social desirability bias

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a thesis, dissertation , or research paper , in order to situate your work in relation to existing knowledge.

A literature review is a survey of credible sources on a topic, often used in dissertations , theses, and research papers . Literature reviews give an overview of knowledge on a subject, helping you identify relevant theories and methods, as well as gaps in existing research. Literature reviews are set up similarly to other  academic texts , with an introduction , a main body, and a conclusion .

An  annotated bibliography is a list of  source references that has a short description (called an annotation ) for each of the sources. It is often assigned as part of the research process for a  paper .  

A systematic review is secondary research because it uses existing research. You don’t collect new data yourself.

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Literature Reviews: Systematic, Scoping, Integrative

Characteristics of review types, choosing a review type.

Steps in a Systematic/Scoping/Integrative Review

Confirming the Knowledge Gap

Standards and reporting guidelines.

  • Creating a Search Strategy
  • Limits and Inclusion Criteria
  • Review Protocols
  • Elements of a Systematic Review
  • Review Tools and Applications

Additional Resources

  • JBI Manual for Evidence Synthesis Process outlines for multiple types of evidence reviews. A great source to cite in your methods section.
  • PRISMA Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Guidance for authors and peer reviewers on best practices in reporting for evidence reviews. Includes extensions for different types of reviews, including scoping reviews

Not sure which review type is right for your research question? Check out the links below for help choosing.

  • What Review is Right for You? v2 14 page PDF survey to help you determine which review type might work best for you. Very thorough!
  • Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach. Munn, Z., Peters, M. D. J., Stern, C., Tufanaru, C., McArthur, A., & Aromataris, E. (2018). Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach. BMC Medical Research Methodology, 18(1), 143. https://doi.org/10.1186/s12874-018-0611-x

Creating an effective search for a systematic review means walking a tightrope between comprehensiveness and managability. You want to try to include all of the studies that could possibly be relevant while simultaneously getting your search results down to a number of articles that you can realistically review. 

The Basic Process:

  • Develop a research question.
  • Consult with a librarian for help with steps 3-16.
  • Search databases to see if a review has already been published on your topic. 
  • Search protocol repositories to see if a review on your topic is planned.
  • Select the type of review (systematic, scoping, integrative). This will require running some test searches to see if there is enough literature to merit a systematic review.
  • Select databases.
  • Select grey literature sources (if applicable). Read this article for helpful suggestions on systematically searching for grey literature.
  • Formulate an initial search for one of your selected databases. For tips on searching, consult our Mastering Keyword Searching guide.
  • Review results from initial search, scanning titles, abstracts, and subject headings to identify additional terms. You may also want to use the subject heading database you can find within each database.
  • Run the search again. Continue to add relevant terms and adjust the scope of your question (which may require eliminating terms) until results are a reasonable size and predominantly relevant to your question.
  • When you think your search is nearly final, gather 2-3 of your most relevant articles and test their reference lists against your search results. If your search contains a large majority of the relevant articles from those reference lists, your have your final search (remember no search is ever perfect, and you will nearly always add articles you find via reference lists, recommendations, etc. that did not appear in your search results). 
  • Translate your search to your other databases. Generally your keywords will stay the same across databases, but you will most likely need to adjust your subject headings, because those can vary from database to database.
  • Ask a librarian to peer review your search. Try the PRESS checklist . 
  • Develop inclusion and exclusion criteria in preparation for reviewing articles (this step may come later for a scoping review)
  • Write a protocol .
  • Database name (be as specific as possible, including the full title, especially for databases that are offered in multiple formats, e.g. Ovid Medline) and dates of coverage.
  • Search terms, including indicating which are subject headings and which are keywords plus any limitations to where the keywords were search if relevant.
  • Database limits/filters applied to the results (e.g. publication year, language, etc.).
  • Date of your search.
  • Number of results.
  • Begin title/abstract screening. Two reviewers for each item is best practice.
  • Begin full-text review of the articles still remaining. Again, two reviewers for each item is best practice. 
  • Conduct citation mining for the articles that make it through full-text review. That means looking at reference lists (backwards searching) and searching for articles that cite back to the article you have (forward searching). You might also consider setting aside all of the systematic and scoping reviews that came up with your search (generally those are excluded from your review) and mining their reference lists as well. Repeat the title/abstract screening and full-text reviews for the articles identified through citation mining.
  • Check all articles that made it through the full-text review for retractions, and remove any articles that have been retracted. 
  • If doing a systematic review, conduct a critical appraisal of included articles (aka Risk of Bias Assessment).
  • Covidence. (2024). A practical guide to data extraction for intervention systematic reviews .
  • Pollock et al. (2023). Recommendations for the extraction, analysis, and presentation of results in scoping reviews . JBI Evidence Synthesis, 21 (3), 520-532. 
  • Prepare your manuscript (for information on writing each section of your manuscript, see our guide to Writing up Your Own Research ). 

Before beginning your review, you need to be sure that no other reviews with the same research question as yours already exist or are in progress. This is easily done by searching research databases and protocol registries.

Databases to Check

difference between a literature review and systematic review

Protocol Registries

  • PROSPERO PROSPERO accepts registrations for systematic reviews, rapid reviews and umbrella reviews. PROSPERO does not accept scoping reviews or literature scans. Sibling PROSPERO sites register systematic reviews of human studies and systematic reviews of animal studies.

difference between a literature review and systematic review

It is a good idea to familiarize yourself with the standards and reporting guidelines for the type of review you are planning to do. Following the standards/guidelines as you plan and execute your review will help ensure that you minimize bias and maximize your chances of getting published.

Systematic Reviews

  • PRISMA Statement The PRISMA statement is currently the standards and guidelines of choice for systematic reviews. At the link you will find the statement as well as explanations of each element, a checklist of elements, a PRISMA flow diagram template, and more.

difference between a literature review and systematic review

  • IOM Finding What Works in Healthcare: Standards for Systematic Reviews Standards from the National Academy of Medicine and National Academies Press. The free download link is all the way over on the right.

Scoping Reviews

  • PRISMA-SCR Extension for Scoping Reviews A PRISMA statement, explanation and checklist specifically for scoping reviews.
  • Updated methodological guidance for the conduct of scoping reviews While the PRISMA-SCR provides reporting guidelines, these guidelines from JBI are for how to actually plan and do your review. This is the explanation for updates made to the manual linked below. You can skip this article and go directly to the JBI manual if you prefer.

Integrative Reviews

  • Whittemore, R., & Knafl, K. (2005). The integrative review: updated methodology. Journal of Advanced Nursing, 52 (5), 546–553. This article is the current standard for designing an integrative review. more... less... https://doi.org/10.1111/j.1365-2648.2005.03621.x
  • Tavares de Souza, M., Dias da Silva, M., & de Carvalho, R. (2010). Integrative review: What is it? How to do it? Einstein, 8 (1). https://doi.org/10.1590/s1679-45082010rw1134
  • Next: Creating a Search Strategy >>
  • Last Updated: Apr 11, 2024 9:51 AM
  • URL: https://libguides.massgeneral.org/reviews

difference between a literature review and systematic review

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What is the difference between a systematic review and a systematic literature review?

By Carol Hollier on 07-Jan-2020 12:42:03

Systematic Reviews vs Systematic Literature Reviews | IFIS Publishing

For those not immersed in systematic reviews, understanding the difference between a systematic review and a systematic literature review can be confusing.  It helps to realise that a “systematic review” is a clearly defined thing, but ambiguity creeps in around the phrase “systematic literature review” because people can and do use it in a variety of ways. 

A systematic review is a research study of research studies.  To qualify as a systematic review, a review needs to adhere to standards of transparency and reproducibility.  It will use explicit methods to identify, select, appraise, and synthesise empirical results from different but similar studies.  The study will be done in stages:  

  • In stage one, the question, which must be answerable, is framed
  • Stage two is a comprehensive literature search to identify relevant studies
  • In stage three the identified literature’s quality is scrutinised and decisions made on whether or not to include each article in the review
  • In stage four the evidence is summarised and, if the review includes a meta-analysis, the data extracted; in the final stage, findings are interpreted. [1]

Some reviews also state what degree of confidence can be placed on that answer, using the GRADE scale.  By going through these steps, a systematic review provides a broad evidence base on which to make decisions about medical interventions, regulatory policy, safety, or whatever question is analysed.   By documenting each step explicitly, the review is not only reproducible, but can be updated as more evidence on the question is generated.

Sometimes when people talk about a “systematic literature review”, they are using the phrase interchangeably with “systematic review”.  However, people can also use the phrase systematic literature review to refer to a literature review that is done in a fairly systematic way, but without the full rigor of a systematic review. 

For instance, for a systematic review, reviewers would strive to locate relevant unpublished studies in grey literature and possibly by contacting researchers directly.  Doing this is important for combatting publication bias, which is the tendency for studies with positive results to be published at a higher rate than studies with null results.  It is easy to understand how this well-documented tendency can skew a review’s findings, but someone conducting a systematic literature review in the loose sense of the phrase might, for lack of resource or capacity, forgo that step. 

Another difference might be in who is doing the research for the review. A systematic review is generally conducted by a team including an information professional for searches and a statistician for meta-analysis, along with subject experts.  Team members independently evaluate the studies being considered for inclusion in the review and compare results, adjudicating any differences of opinion.   In contrast, a systematic literature review might be conducted by one person. 

Overall, while a systematic review must comply with set standards, you would expect any review called a systematic literature review to strive to be quite comprehensive.  A systematic literature review would contrast with what is sometimes called a narrative or journalistic literature review, where the reviewer’s search strategy is not made explicit, and evidence may be cherry-picked to support an argument.

FSTA is a key tool for systematic reviews and systematic literature reviews in the sciences of food and health.

pawel-czerwinski-VkITYPupzSg-unsplash-1

The patents indexed help find results of research not otherwise publicly available because it has been done for commercial purposes.

The FSTA thesaurus will surface results that would be missed with keyword searching alone. Since the thesaurus is designed for the sciences of food and health, it is the most comprehensive for the field. 

All indexing and abstracting in FSTA is in English, so you can do your searching in English yet pick up non-English language results, and get those results translated if they meet the criteria for inclusion in a systematic review.

FSTA includes grey literature (conference proceedings) which can be difficult to find, but is important to include in comprehensive searches.

FSTA content has a deep archive. It goes back to 1969 for farm to fork research, and back to the late 1990s for food-related human nutrition literature—systematic reviews (and any literature review) should include not just the latest research but all relevant research on a question. 

You can also use FSTA to find literature reviews.

FSTA allows you to easily search for review articles (both narrative and systematic reviews) by using the subject heading or thesaurus term “REVIEWS" and an appropriate free-text keyword.

On the Web of Science or EBSCO platform, an FSTA search for reviews about cassava would look like this: DE "REVIEWS" AND cassava.

On the Ovid platform using the multi-field search option, the search would look like this: reviews.sh. AND cassava.af.

In 2011 FSTA introduced the descriptor META-ANALYSIS, making it easy to search specifically for systematic reviews that include a meta-analysis published from that year onwards.

On the EBSCO or Web of Science platform, an FSTA search for systematic reviews with meta-analyses about staphylococcus aureus would look like this: DE "META-ANALYSIS" AND staphylococcus aureus.

On the Ovid platform using the multi-field search option, the search would look like this: meta-analysis.sh. AND staphylococcus aureus.af.

Systematic reviews with meta-analyses published before 2011 are included in the REVIEWS controlled vocabulary term in the thesaurus.

An easy way to locate pre-2011 systematic reviews with meta-analyses is to search the subject heading or thesaurus term "REVIEWS" AND meta-analysis as a free-text keyword AND another appropriate free-text keyword.

On the Web of Science or EBSCO platform, the FSTA search would look like this: DE "REVIEWS" AND meta-analysis AND carbohydrate*

On the Ovid platform using the multi-field search option, the search would look like this: reviews .s h. AND meta-analysis.af. AND carbohydrate*.af.  

Related resources:

  • Literature Searching Best Practise Guide
  • Predatory publishing: Investigating researchers’ knowledge & attitudes
  • The IFIS Expert Guide to Journal Publishing

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Systematic Reviews

  • Types of Literature Reviews

What Makes a Systematic Review Different from Other Types of Reviews?

  • Planning Your Systematic Review
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  • Creating the Search
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  • Grey Literature
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Reproduced from Grant, M. J. and Booth, A. (2009), A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26: 91–108. doi:10.1111/j.1471-1842.2009.00848.x

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What is a systematic review?

A systematic review is a firmly structured literature review, undertaken according to a fixed plan, system or method. As such, it is highly focused on a particular and explicit topic area with strict research parameters. Systematic reviews will often have a detailed plan known as a protocol, which is a statement of the approach and methods to be used in the review prior to undertaking it. 

Systematic review methodology is explicit and precise because it aims to minimise bias, thereby enhancing the reliability of any conclusions. It is therefore considered an evidence-based approach. Systematic reviews are commonly used by health professionals, but also policy makers and researchers. 

There is information about the difference between a systematic review and a literature review on this page. If you are undertaking systematic approach to a literature review, however, you might find certain aspects of this guide useful. 

LITERATURE REVIEW VS SYSTEMATIC REVIEW

You can find further information on literature reviews on our  literature reviews page .

How we can help

What we need you to do: .

  • Have a firm idea of your research question or area 
  • List your main keywords and alternatives. You may want to use a table to organise your keywords. 
  • Think about how you will use your keywords to search using connectors such as AND/OR 
  • Define what you want to include and exclude from your search 
  • Consider where you want to search 
  • Run some initial searches and identify any problems or issues you want to discuss 

What your Librarian can help you with:  

  • Identifying relevant databases and other subject resources that could be used to supplement your review 
  • Demonstrating library resources for use in the review  
  • Replicating searches on other databases and resources 
  • Reviewing your search strategy/approach 
  • Directing you to referencing software support 
  • Suggesting ways to save and document your search results 
  • Helping to locate difficult to find material, using the  Request It! service
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Systematic Reviews and Meta-Analysis: A Guide for Beginners

Joseph l. mathew.

Department of Pediatrics, Advanced Pediatrics Centre, PGIMER, Chandigarh, India

Systematic reviews involve the application of scientific methods to reduce bias in review of literature. The key components of a systematic review are a well-defined research question, comprehensive literature search to identify all studies that potentially address the question, systematic assembly of the studies that answer the question, critical appraisal of the methodological quality of the included studies, data extraction and analysis (with and without statistics), and considerations towards applicability of the evidence generated in a systematic review. These key features can be remembered as six ‘A’; Ask, Access, Assimilate, Appraise, Analyze and Apply. Meta-analysis is a statistical tool that provides pooled estimates of effect from the data extracted from individual studies in the systematic review. The graphical output of meta-analysis is a forest plot which provides information on individual studies and the pooled effect. Systematic reviews of literature can be undertaken for all types of questions, and all types of study designs. This article highlights the key features of systematic reviews, and is designed to help readers understand and interpret them. It can also help to serve as a beginner’s guide for both users and producers of systematic reviews and to appreciate some of the methodological issues.

Additional material related to this paper is available with the online version at www.indianpediatrics.net

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Systematic reviews vs meta-analysis: what’s the difference?

Posted on 24th July 2023 by Verónica Tanco Tellechea

""

You may hear the terms ‘systematic review’ and ‘meta-analysis being used interchangeably’. Although they are related, they are distinctly different. Learn more in this blog for beginners.

What is a systematic review?

According to Cochrane (1), a systematic review attempts to identify, appraise and synthesize all the empirical evidence to answer a specific research question. Thus, a systematic review is where you might find the most relevant, adequate, and current information regarding a specific topic. In the levels of evidence pyramid , systematic reviews are only surpassed by meta-analyses. 

To conduct a systematic review, you will need, among other things: 

  • A specific research question, usually in the form of a PICO question.
  • Pre-specified eligibility criteria, to decide which articles will be included or discarded from the review. 
  • To follow a systematic method that will minimize bias.

You can find protocols that will guide you from both Cochrane and the Equator Network , among other places, and if you are a beginner to the topic then have a read of an overview about systematic reviews.

What is a meta-analysis?

A meta-analysis is a quantitative, epidemiological study design used to systematically assess the results of previous research (2) . Usually, they are based on randomized controlled trials, though not always. This means that a meta-analysis is a mathematical tool that allows researchers to mathematically combine outcomes from multiple studies.

When can a meta-analysis be implemented?

There is always the possibility of conducting a meta-analysis, yet, for it to throw the best possible results it should be performed when the studies included in the systematic review are of good quality, similar designs, and have similar outcome measures.

Why are meta-analyses important?

Outcomes from a meta-analysis may provide more precise information regarding the estimate of the effect of what is being studied because it merges outcomes from multiple studies. In a meta-analysis, data from various trials are combined and generate an average result (1), which is portrayed in a forest plot diagram. Moreover, meta-analysis also include a funnel plot diagram to visually detect publication bias.

Conclusions

A systematic review is an article that synthesizes available evidence on a certain topic utilizing a specific research question, pre-specified eligibility criteria for including articles, and a systematic method for its production. Whereas a meta-analysis is a quantitative, epidemiological study design used to assess the results of articles included in a systematic-review. 

Remember: All meta-analyses involve a systematic review, but not all systematic reviews involve a meta-analysis.

If you would like some further reading on this topic, we suggest the following:

The systematic review – a S4BE blog article

Meta-analysis: what, why, and how – a S4BE blog article

The difference between a systematic review and a meta-analysis – a blog article via Covidence

Systematic review vs meta-analysis: what’s the difference? A 5-minute video from Research Masterminds:

  • About Cochrane reviews [Internet]. Cochranelibrary.com. [cited 2023 Apr 30]. Available from: https://www.cochranelibrary.com/about/about-cochrane-reviews
  • Haidich AB. Meta-analysis in medical research. Hippokratia. 2010;14(Suppl 1):29–37.

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Concern about the risk of aerosol contamination from ultrasonic scaler: a systematic review and meta-analysis

  • Priscilla Gonçalves Lomardo 1 ,
  • Mariana Campello Nunes 1 ,
  • Patrícia Arriaga 1 ,
  • Lívia Azeredo Antunes 2 ,
  • Aldir Machado 1 ,
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BMC Oral Health volume  24 , Article number:  417 ( 2024 ) Cite this article

162 Accesses

Metrics details

Many instruments used in dentistry are rotary, such as handpieces, water syringes, and ultrasonic scalers that produce aerosols. The spray created by these instruments can carry, in addition to water, droplets of saliva, blood, and microorganisms, which can pose a risk of infections for healthcare professionals and patients. Due to the COVID-19 pandemic, this gained attention.

The aim was to carry out a systematic review of the evidence of the scope of the aerosol produced by ultrasonic scaler in environmental contamination and the influence of the use of intraoral suction reduction devices.

Scientific literature was searched until June 19, 2021 in 6 databases: Pubmed, EMBASE, Web of science, Scopus, Virtual Health Library and Cochrane Library, without restrictions on language or publication date. Studies that evaluated the range of the aerosol produced by ultrasonic scaler during scaling/prophylaxis and the control of environmental contamination generated by it with the use of low (LVE) and high (HVE) volume evacuation systems were included.

Of the 1893 potentially relevant articles, 5 of which were randomized controlled trials (RCTs). The meta-analysis of 3 RCTs showed that, even at different distances from the patient’s oral cavity, there was a significant increase in airborne bacteria in the dental environment with the use of ultrasonic scaler. In contrast, when meta-analysis compared the use of HVE with LVE, there was no significant difference ( P  = 0.40/CI -0.71[-2.37, 0.95]) for aerosol produced in the environment.

Conclusions

There is an increase in the concentration of bioaerosol in the dental environment during the use of ultrasonic scaler in scaling/prophylaxis, reaching up to 2 m away from the patient’s mouth and the use of LVE, HVE or a combination of different devices, can be effective in reducing air contamination in the dental environment, with no important difference between different types of suction devices.

Peer Review reports

Every aspect of life has been influenced by an outbreak of the new coronavirus disease (COVID-19) in China [ 1 ] which greatly changed the routine in dental clinics. Due to the COVID-19 pandemic, the Centers for Disease Control and Prevention (CDC) recommended in principle, avoiding aerosol-generating procedures in the dental environment whenever possible, not using equipment that produces aerosols, and prioritizing the use of hand instruments only [ 2 ].

However, many of the instruments used in dentistry are rotary, such as handpieces, water syringes, and ultrasonic scalers. The spray created by these instruments can carry, in addition to water, droplets of saliva, blood, and microorganisms, which can pose a risk of infections for healthcare professionals and patients [ 3 ].

Particles formed by liquids and solids dispersed and suspended in the air are aerosols, which become bioaerosols when microorganisms excreted by the body dissolve with the aerosols through the act of coughing, breathing vigorously, sneezing, or speaking loudly [ 4 , 5 ].

Micik et al. used the terms “aerosol” and “splatter” in 1969, in which they were defined as particles smaller and larger than 50 micrometers (µm) in diameter, respectively. The first term refers to small particles that remain in the air for a period of time before being deposited on surfaces or entering the airways. The second are particles or droplets that are forcibly ejected from the operating site, reaching a trajectory similar to that of a bullet until they come into contact with a surface or fall to the ground [ 6 ].

With a simulation using computational fluid dynamics to quantify the transport of large droplets and aerosols in dental clinic environments, we better understand the risks associated with a common dental procedure such as ultrasonic scaling. Aerosols below 15 μm remain in the air for up to 7.13 min on average and can travel up to 25.45 m on average from their source, potentially contaminating entire clinics [ 3 ].

The water spray droplets produced during ultrasonic scaling are extremely light in weight and release large numbers of microorganisms into the air [ 7 ]. The bacterial challenge appears to be considerable and it is likely that viruses and bacteria can be spread in this way [ 8 ]. It should also be taken into account that particles ranging from 0.3 to 5 µm increase significantly after instrumentation with an ultrasonic scaler [ 9 ] and the variation in ultrasonic frequency causes an increase in surface contamination, as well as the type of suction used, influences the degree of contamination [ 10 ].

Due to the fact that ultrasonic scaler is one of the equipment that produces the most aerosol and can be responsible for spreading the SARS-CoV-2 virus during dental care, which is a major concern among dentists, especially periodontists, this work aimed to carry out a systematic review of the evidence of the reach of the aerosol, produced by ultrasonic scaler during scaling and prophylaxis, in the contamination of the dental environment and the influence of the use of intraoral suction devices in the reduction of this contamination.

Materials and methods

The present systematic review was registered in the PROSPERO (International Prospective Register of Systematic Reviews) [ 11 ] under the number #CRD42020191209 and conducted in accordance with the recommendations of the “Cochrane Handbook for Systematic Reviews of Interventions” [ 12 ] and following the guidelines of the PRISMA checklist [ 13 ]. Clinical questions were organized using the “PECO” (Population, Exposition, Comparison and Outcome) strategy.

The objective of this study was to carry out a systematic review of the evidence of the reach of the aerosol in distance traveled, produced by ultrasonic scaler during scaling and prophylaxis, in the contamination of the dental environment and the influence of the use of intraoral suction devices in the reduction of this contamination.

Focus question

What is the evidence of the reach of the aerosol in distance traveled produced by scaling with ultrasonic scaler in the contamination of the dental environment and the influence of intraoral suction devices in the reduction of this contamination?

Search strategy

Scientific literature was searched in six electronic databases until June 19, 2021 through Pubmed ( https://pubmed.ncbi.nlm.nih.gov ), EMBASE ( https://www.embase.com ), Web of Science ( www.webofscience.com ), Scopus ( www.scopus.com ), Virtual Health Library (VHL - in the LILACS, BBO, and IBECS databases) (bvsalud.org), and Cochrane Library ( www.cochranelibrary.com ). No restrictions on language or publication date were imposed. In addition to the electronic search, a manual search was performed using the reference lists of the selected articles. In addition, information was searched in the OpenGrey open access database [ 14 ] for unpublished studies (grey literature) using the same terms.

The following MeSH terms (Medical Subjects Headings) [ 15 ] were used for the search: “dental care”, “dental prophylaxis”, “ultrasonic therapy”, “dental scaling” and “aerosols”. In addition, other synonyms of DeCS (Health Sciences Descriptors) [ 16 ] and free terms were applied in the search, they are: “delivery of dental care”, “dental treatment”, “ultrasonic instrumentation”, “ultrasonic dental scale”, “ultrasonic scaling”, “dental cleaning”, “subgingival scaling”, “supragingival scaling”, “splatter”, “aerosol contamination”, “bioaerosol”, “bio-aerosol”, “airborne”, “dental aerosols”. All descriptors were connected through the Boolean operators “AND” and “OR”. The search strategy is described in Tables  1 and 2 . The Endnote web software was used to organize the studies [ 17 ].

Selection criteria

The eligibility requirements were outlined according to the PECOS strategy:

P (Population of interest): patients undergoing dental scaling treatment with ultrasonic scaler were included;

E (Exposure): Aerosol produced by ultrasonic scaler;

C (Comparison): comparison of contamination reduction with the use of different intraoral suction devices;

O (Outcome): contamination of the environment caused by aerosol from ultrasonic scaler;

S (Study design): randomized controlled trials (RCT) were included.

Exclusion criteria were studies that use manual scaling; studies that included prior use of mouthwashes and studies that used external air decontamination systems.

The eligibility requirements considered for studies to be included in this review were: human studies; studies that evaluated the range of the aerosol produced by ultrasonic during scaling procedures; studies that evaluated the contamination of the environment by the aerosol produced by dental ultrasonic and studies that used intraoral suction reduction devices to control the aerosol.

Screening process

At first, two reviewers (PGL and MCN) independently selected titles and abstracts. Disagreements were resolved through discussion with a third reviewer (TRSA). Studies that appeared to meet the inclusion criteria or that did not have sufficient information in their titles and abstracts were selected for evaluation of the full article at a later stage. The same reviewers independently assessed full texts to determine whether studies were eligible. Data extraction and risk of bias were performed in studies that met the inclusion criteria.

Data extraction

All data were extracted individually by two reviewers (PGL and MCN) and discrepancies were discussed by a third reviewer (TRSA). Reviewers were calibrated in applying the inclusion and exclusion criteria applied to a sample of 20% of the studies to determine inter-rater agreement (Kappa = 0.80). All necessary data were found in the studies, and it is not necessary to contact the authors for clarification.

The synthesis of the extracted data was organized in table with the following variables: first author, year of publication, country of origin, type of clinic, patient involved, type of suction device, collected distances, type of incubation, outcome measure and results.

Outcome measures

The outcome measure was the count of bacterial colony forming units (CFU) present in the oral aerosol, produced by ultrasonic scaler during scaling and prophylaxis, collected through plates with culture media positioned at different distances around the patient and/or the clinic.

Assessment of the risk of bias and quality

The quality assessment of the studies was performed by the same reviewers (PGL and MCN) independently and any disagreement between them was resolved through consultation with a third party (TRSA).

The Cochrane Collaboration Tool was used to assess the risk of bias using the updated Risk of Bias 2 (RoB 2) tool [ 18 ].

This tool evaluates five domains that can be classified as: low risk of bias, some concerns or high risk of bias. The domains are:

D1: Randomization process;

D2: Deviations from intended interventions;

D3: Missing result data;

D4: Measurement of the result; and.

D5: Selection of reported result.

This tool also allows for ranking the overall risk of bias, which receives the least favorable ranking among the assessed risks for the domains. The judgment about the risk of bias resulting from each domain is proposed by an algorithm, based on signaling questions, which help the reviewer to assess the important factors for the evaluation of each domain.

Statistical analysis

Meta-analyses were performed using the Review Manager software, Version 5.4.1 (Nordic Cochrane Center, Cochrane Collaboration) [ 19 ]. A meta-analysis of the reach of the aerosol in the contamination of the environment and a meta-analysis of the reduction of the contamination of the environment were performed, comparing the use of high-volume evacuation (HVE) and low-volume evacuation (LVE), both expressed in mean and standard deviation of CFU/m³. The inverse variance statistical method was used, with a random effects analysis model. Forest plots were calculated for 95% confidence intervals (CI) and P values. Heterogeneity between study results and quantification of inconsistency was assessed using the I 2 test. Results were expressed as standardized mean difference. Subgroups were established according to the distance of the aerosol reach in relation to the patient’s oral cavity.

Analysis of certainty of evidence

The quality of evidence (certainty in effect estimates) was analyzed by two reviewers (PGL and PA) using the assessment, development and assessment of recommendations (GRADE) approach [ 20 ]. The domains evaluated in clinical studies were: risk of bias, inconsistency, indirectness, imprecision and publication bias.

GRADE defines the quality of scientific evidence in a clearer and more objective way, and can be classified as high, moderate, low or very low.

Selection of studies

A total of 1893 relevant records were found: 298 references from Pubmed, 191 from Web of Science, 502 from Scopus, 413 from EMBASE, 385 from VHL, 103 from Cochrane Library and 1 from Opengrey. 619 duplicate references were removed; 1274 studies were analyzed by title and abstract; 1236 were excluded after this selection; and 38 studies were selected for full-text analysis. Among the 38 selected studies, 33 studies were excluded. Figure  1 outlines the search process and reasons for exclusions. Five randomized controlled trials (RCTs) were included. The synthesis of the extracted data was organized in the Table  3 .

figure 1

PRISMA 2020 flow diagram (13) of the screening and selection process

Study characteristics

The studies originated from 3 different countries: 1 from India [ 21 ], 3 from the United States [ 22 , 23 , 24 ] and 1 from Netherlands [ 25 ]. All selected articles were written in English. All included studies used ultrasonic scaler during treatments, but not all specified the type used, whether piezoelectric, magnetostrictive or sonic. In addition, they used high-volume and/or low-volume suction devices and made comparisons between two types of suction. Four studies were carried out in a dental environment with a single and only chair [ 21 , 22 , 23 , 25 ], and one study used a multi-chair environment [ 24 ].

Two studies had as sample patients diagnosed with periodontal disease [ 21 , 25 ]. The other studies were considered as if they had evaluated periodontally healthy patients [ 22 , 23 , 24 ].

All the studies measured aerosol contamination using colony forming units (CFU). The culture medium varied between studies. Some studies used culture media for aerobic and anaerobic bacteria [ 25 ], others only for aerobic bacteria culture [ 21 , 23 , 24 ], and one study only used anaerobic culture [ 22 ].

Assessment of risk of bias and quality

The quality of randomized controlled trials is shown in Fig.  2 . None of the randomized controlled trials scored the highest in the quality analysis. The five studies did not describe the allocation sequence and two [ 21 , 25 ] did not analyze the data according to a pre-specified analysis plan. Thus, they were characterized as some concerns.

figure 2

Risk of bias in randomized controlled trials analyzed using the RoB 2 tool

Meta-analysis

Two meta-analyses of RCTs were performed. The first in relation to contamination of the environment before and during the use of ultrasonic scaler and the second, referring to the reduction of contamination when comparing the use of high-volume suction versus low-volume suction. The analyzes carried out, taking into account the primary outcome of contamination of the dental environment, are shown in Fig.  3 , and the secondary outcome related to the reduction of contamination of the environment, comparing the use of HVE and LVE, is shown in Fig.  4 .

figure 3

Analysis 1 – Contamination of the dental environment by aerosol produced during scaling with ultrasonic, in randomized controlled studies. Primary outcome: contamination of the dental environment. Subtitle: SD: Standard deviation, CI: Confidence interval

figure 4

Analysis 2 - Reduction in the level of aerosol contamination by comparing the use of high (HVE) and low (LVE) volume suction in randomized controlled trials. Secondary outcome: reduction in the level of contamination. Subtitle: SD: Standard deviation, CI: Confidence interval

Only three randomized controlled studies [ 23 , 24 , 25 ] were included in the meta-analysis of data on environmental contamination and were divided into two subgroups: one considering data at a distance of less than or equal to 60 cm and another at a distance greater than or equal to 120 cm. For the contamination reduction analysis comparing different types of suction, data from three RCTs [ 21 , 23 , 25 ] were also included.

In the meta-analysis of the RCTs [ 23 , 24 , 25 ] (Fig.  3 ), the studies were homogeneous and indicated that, both at a distance less than or equal to 60 cm and at a distance greater than or equal to 120 cm from the patient’s oral cavity, there is disclosure of a smaller amount of bacteria in the dental environment before the ultrasonic procedure, even though high-volume suction was used, showing a significant increase in bacteria in the air in the dental environment with the use of ultrasonic scaler ( P  < 0.00001/CI 0.99, [0.67, 1.31]), quantifying the magnitude of the effect, according to the Cohen scale [ 26 ], in large.

On the other hand, when a meta-analysis was performed comparing the use of HVE with LVE (Fig.  4 ), there was no significant difference ( P  = 0.40/CI -0.71[-2.47, 0.95]) in reducing the amount of aerosol produced in the environment, quantifying the magnitude of the effect, according to the Cohen scale [ 26 ], in medium.

Certainty of evidence

The certainty of the evidence is represented in Tables  3 and 4 .

In the subgroup analysis for distances less than or equal to 60 cm and greater than or equal to 120 cm from the oral cavity, contamination of the dental environment with the use of ultrasonic scaler was greater than without the use of ultrasonic scaler and the certainty of the evidence was considered moderate for both distances (Table  4 ).

When comparing the use of high-volume suction with the use of low-volume suction in reducing levels of contamination in the dental environment, the certainty of the evidence was considered low (Table  5 ), with no significant differences between these devices. Serious problems with inconsistency and imprecision were detected in the studies included in the meta-analyses.

Aerosols and splashes are the main sources of environmental contamination during dental procedures [27]. This fact has become one of the biggest concerns among dentists during the COVID-19 pandemic. In order to review the evidence related to air contamination generated by the reach of the aerosol produced during the use of ultrasonic scaler for scaling and prophylaxis, a detailed search was carried out in six databases and five randomized controlled trials who met the inclusion criteria were found.

The high bacterial counts (log10 5.0 CFUs/mL) indicate that there is a worrying contamination of the air after the use of ultrasonic scaler, even when using a high volume suction combined with another device [ 22 ]. This contamination was shown in the first meta-analysis (Fig.  3 ) carried out on the results of randomized controlled studies [ 23 , 24 , 25 ], in which even with the use of high-volume suction, there was a significant difference in the increase of bacteria in the air ( P  < 0.00001/CI 0.99, [0.67, 1.31]).

Of the five randomized controlled trials included, only two [ 23 , 24 ] found a statistically significant reduction in the mean CFUs ( p  < 0.001) collected during the use of ultrasonic scaler when using two different suction methods, where one used the high-pressure suction cannula volume attached directly to the ultrasonic pen [ 23 ], and the other the high volume suction combination added plus a high volume suction hose [ 24 ]. The other RCTs [ 21 , 22 ] did not find significant differences ( p  > 0.05) between the two suction methods studied. However, the number of bacteria in the air tends to be higher when conventional suction devices are used, that is, low volume ones [ 25 ]. Furthermore, the high-volume suction device used separately, without any modification, does not appear to be as effective in reducing the amount of aerosol formed [ 21 ]. Despite this, when a meta-analysis (Fig. 4) was performed comparing the use of high and low volume suction devices in three RCTs [ 21 , 23 , 25 ], there was no significant difference in the amount of aerosol formed during the use of ultrasonic scaler.

As limitations of the study, a difference was observed in the methodologies used by the studies, which makes a more accurate comparison difficult, as the distance at which the agar plates are placed to collect the samples, the plate exposure time and the different dental environments, can influence the comparison of results. Two RCTs [ 22 , 23 ] placed the sample collection plates six inches (15.24 cm) from the patient’s mouth and the others used different distances such as 40 and 150 cm [ 25 ]; 12 and 20 inches (approximately 30 and 50 cm) [ 21 ] and at three different distances between 2 and 4 feet (approximately 60–120 cm) (24). Regarding the exposure time of the plaque during the use of ultrasound, there was a variation between 5 min [ 23 , 25 ] and 20 min [ 24 ]. Therefore, the shorter the plate exposure time and the greater the distance, the lower the chance of CFU collection. And regarding the dental environments just one study used a multi-chair environment [ 24 ].

Another limitation of the study refers to the fact that it was not possible to assess publication bias as only five studies were included for meta-analysis, with low power to detect possible bias.

There is an increase in the concentration of bioaerosol in the dental environment during the use of ultrasonic scaler in scaling/prophylaxis, reaching up to 2 m away from the patient’s mouth.

The use of good suction, whether low volume, high volume or a combination of different devices, can be effective in reducing air contamination in the dental environment, with no important difference between different types of suction devices.

Final considerations: To minimize the risk of infection for the operator, it is recommended to use adequate precautions, such as the use of adapted masks. And to minimize the risk of cross-infection, especially between patients, and contamination of surfaces, it is recommended to space appointments by at least 30 min and always use suction devices respectively.

Data availability

The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.

Abbreviations

Colony forming units

Confidence intervals

Coronavirus disease 2019

Centers for Disease Control and Prevention

High Volume Suction

Low Volume Suction

Population, Exposition, and Outcome

Randomized controlled trials

Risk of Bias 2

Severe acute respiratory syndrome coronavirus 2

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Priscilla Gonçalves Lomardo, Mariana Campello Nunes, Patrícia Arriaga, Aldir Machado, Telma Regina da Silva Aguiar & Priscila Ladeira Casado

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Conceptualisation, Methodology, Investigation, Formal analysis, Writing - Original Draft (Priscilla Lomardo, Mariana Campello Nunes, Patrícia Arriaga); Formal analysis, Data Curation, Writing - Review & Editing, Visualisation (Valquiria Quinelato, Aldir Machado); Conceptualisation, Methodology, Writing - Review & Editing, Visualisation, Project administration (Priscila Ladeira Casado, Lívia Azeredo Antunes, Telma Regina da Silva Aguiar).

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Gonçalves Lomardo, P., Nunes, M.C., Arriaga, P. et al. Concern about the risk of aerosol contamination from ultrasonic scaler: a systematic review and meta-analysis. BMC Oral Health 24 , 417 (2024). https://doi.org/10.1186/s12903-024-03996-2

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  7. Systematic, Scoping, and Other Literature Reviews: Overview

    A systematic review, however, is a comprehensive literature review conducted to answer a specific research question. Authors of a systematic review aim to find, code, appraise, and synthesize all of the previous research on their question in an unbiased and well-documented manner.

  8. Systematic Review

    Systematic review vs. literature review. A literature review is a type of review that uses a less systematic and formal approach than a systematic review. Typically, an expert in a topic will qualitatively summarize and evaluate previous work, without using a formal, explicit method. ... (risk ratios and differences between means) for the ...

  9. Systematic review vs literature review: Some essential differences

    Apart from systematic literature review, some other common types of literature review are1: The most commonly used form of review, however, is the systematic literature review. Compared to the other types of literature reviews described above, this one requires a more rigorous and well-defined approach. The systematic literature review can be ...

  10. Understanding the Differences Between a Systematic Review vs Literature

    The methodology involved in a literature review is less complicated and requires a lower degree of planning. For a systematic review, the planning is extensive and requires defining robust pre-specified protocols. It first starts with formulating the research question and scope of the research. The PICO's approach (population, intervention ...

  11. Literature reviews vs systematic reviews

    Acommon type of submission at any Journal is a review of the published information related to a topic.These are often returned to their authors without review, usually because they are literature reviews rather than systematic reviews. There is a big difference between the two (Table 1).Here, we summarise the differences, how they are used in academic work, and why a general literature review ...

  12. Introduction to systematic review and meta-analysis

    A systematic review collects all possible studies related to a given topic and design, and reviews and analyzes their results [ 1 ]. During the systematic review process, the quality of studies is evaluated, and a statistical meta-analysis of the study results is conducted on the basis of their quality. A meta-analysis is a valid, objective ...

  13. Literature and systematic reviews

    Systematic reviews. Systematic review is a type of literature review. Unlike other forms of review, where authors can include any articles they consider appropriate, a systematic review aims to remove the reviewer's biases by following a clearly defined, transparent process. There are a number of steps in the process, and each needs to be ...

  14. Literature Reviews: Systematic, Scoping, Integrative

    Review existing literature on a topic, generally conducted when literature is diverse in type (heterogenous) or in its nascency when more specific questions are unanswerable. ... If doing a systematic review, conduct a critical appraisal of included articles (aka Risk of Bias Assessment). Begin data extraction and synthesis. Covidence. (2024).

  15. What is the difference between a systematic review and a systematic

    In contrast, a systematic literature review might be conducted by one person. Overall, while a systematic review must comply with set standards, you would expect any review called a systematic literature review to strive to be quite comprehensive. A systematic literature review would contrast with what is sometimes called a narrative or ...

  16. Research Guides: Systematic Reviews: Types of Literature Reviews

    Rapid review. Assessment of what is already known about a policy or practice issue, by using systematic review methods to search and critically appraise existing research. Completeness of searching determined by time constraints. Time-limited formal quality assessment. Typically narrative and tabular.

  17. What is a Systematic Review?

    A systematic review is a firmly structured literature review, undertaken according to a fixed plan, system or method. As such, it is highly focused on a particular and explicit topic area with strict research parameters. Systematic reviews will often have a detailed plan known as a protocol, which is a statement of the approach and methods to ...

  18. Traditional reviews vs. systematic reviews

    They aim to summarise the best available evidence on a particular research topic. The main differences between traditional reviews and systematic reviews are summarised below in terms of the following characteristics: Authors, Study protocol, Research question, Search strategy, Sources of literature, Selection criteria, Critical appraisal ...

  19. Comparing Integrative and Systematic Literature Reviews

    A literature review is a systematic way of collecting and synthesizing previous research (Snyder, 2019).An integrative literature review provides an integration of the current state of knowledge as a way of generating new knowledge (Holton, 2002).HRDR is labeling Integrative Literature Review as one of the journal's four non-empirical research article types as in theory and conceptual ...

  20. Systematic Reviews and Meta-Analysis: A Guide for Beginners

    Systematic reviews involve the application of scientific methods to reduce bias in review of literature. The key components of a systematic review are a well-defined research question, comprehensive literature search to identify all studies that potentially address the question, systematic assembly of the studies that answer the question, critical appraisal of the methodological quality of the ...

  21. Systematic reviews vs meta-analysis: what's the difference?

    A systematic review is an article that synthesizes available evidence on a certain topic utilizing a specific research question, pre-specified eligibility criteria for including articles, and a systematic method for its production. Whereas a meta-analysis is a quantitative, epidemiological study design used to assess the results of articles ...

  22. The Difference Between Narrative Review and Systematic Review

    When the word "review" alone is used to describe a research paper, the first thing that should come to mind is that it is a literature review. Almost every researcher starts off their career with literature reviews. To know the difference between a systematic review and a literature review, read on here. Traditional literature reviews are ...

  23. Behavioral Sciences

    A systematic review was conducted of the literature published between 2010 and 2023 in the PsycINFO, ERIC, Education, and Psychology databases. An initial 1176 studies were reviewed by abstract, of which 485 were read in full text, leading to the selection and analysis of 22 studies.

  24. Differences Between Traumatic and Degenerative Medial Meniscus

    Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a systematic literature review was performed on December 28, 2022, using "medial root tear" as a Medical Subject Headings term in the Web of Science database (www.webofscience.com). Only publications with either an English or a German abstract ...

  25. Microorganisms

    A systematic review of the literature was conducted based on the selection and search of articles, available in English, Spanish, or Portuguese in the time frame of 1990-2022, of primary and secondary types in the PUBMED, Science Direct, SciELO, and LILACS databases through descriptors (MeSH) together with "AND": "CCR5"; "CCL5 ...

  26. Concern about the risk of aerosol contamination from ultrasonic scaler

    The present systematic review was registered in the PROSPERO (International Prospective Register of Systematic Reviews) [] under the number #CRD42020191209 and conducted in accordance with the recommendations of the "Cochrane Handbook for Systematic Reviews of Interventions" [] and following the guidelines of the PRISMA checklist [].Clinical questions were organized using the "PECO ...

  27. Interoceptive interventions for posttraumatic stress: A systematic

    The aim of this systematic review was to address these gaps. A search of four databases (Medline, Web of Science, PsycINFO, and Scopus) for English-language peer-reviewed literature published between inception and May 11, 2023, yielded 10,488 records and 19 studies eligible for inclusion. ... Large mean differences were observed for the ...

  28. Pathogens

    This is a systematic review and meta-analysis following the recommendations of PRISMA 2020. ... SARS-CoV-2; type (T): experimental studies. In this sense, the following problem arises: "What is the estimated difference in risk between dogs and cats having SARS-CoV-2?". ... The literature search mechanism was defined by the use of advanced ...

  29. Parkinson's disease and Parkinsonism syndromes: Evaluating iron

    Magnetic resonance imaging (MRI) techniques, such as quantitative susceptibility mapping (QSM) and susceptibility-weighted imaging (SWI), can detect iron deposition in the brain. Iron accumulation in the putamen (PUT) can contribute to the pathogenesis of Parkinson's disease (PD) and atypical Parkinsonian disorders. This systematic review aimed to synthesize evidence on iron deposition in the ...