original research vs systematic review

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Should systematic reviews be submitted to journals as original or review articles?

In the Information for Authors of several (health) related journals, manuscript types may include original research and review articles, among others.

I thought systematic reviews (whether quantitative or qualitative) should be submitted as review submissions, as opposed to, for example, original studies with novel findings based on data collected or analyzed by authors. However, the guides in those journals say a review requires an unstructured abstract, as in narrative reviews.

In this answer , review articles can be considered original observations. So why do some journals distinguish between review articles and original research? And, under which category should systematic reviews be submitted to these journals?

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• There is always the option to do an inquiry where you can propose what you want to write about, and the editors will reply if it fits and under which category. –  BioGeo Commented Dec 22, 2016 at 22:57
• Not to mention that reviews are often "invited" which means that either the journal asked you for it, or you asked the journal and then they sent you an invitation. –  BioGeo Commented Dec 22, 2016 at 22:59

2 Answers 2

I can see a good case to be made on either side:

• A systematic review, unlike a more traditional narrative review, is often an explicit numerical meta-analysis of prior data. Its systematicity allows it to be an actual experiment with objectively verifiable conclusions, and thus it may be reasonably considered original research on a new data set drawn from the literature .
• Systematic reviews still, however, are organization and analysis of other studies, and so could be grouped in with other reviews.

Since both of these are reasonable, I suspect that there is no way to tell which perspective a particular publication subscribes to without reading their guidance to authors or asking their editorial staff (who will no doubt be happy to answer the question).

Under which category should systematic reviews be submitted to these journals?

This will depend on the journal. If a particular journal's instructions are unclear, I suggest:

• looking through the back catalog of previous published papers and noting the article type under which systematic reviews have been classified; or
• contacting the editorial team to clarify the situation.

In the journals I help edit, the classification of the article type is not set in stone, but an internal designation that allows us to determine word counts, reference counts and other production concerns. Sometimes it is difficult to tell. For example, a research article may be written in such a way as to be better classified as a perspective or reflective piece. In those cases, deputy editors work closely with the authors so that they understand how to meet our specifications.

Why do some journals distinguish between review articles and original research?

Journals will have their own reasons. In the journals I help edit -- one for a general medical audience and another for a specialist audience -- review articles are classified separately for two reasons:

• They allow us to feature them with other practice-related state-of-the-art articles.
• Systematic reviews have specific editorial requirements due to their nature. That is, they are generally longer, require longer reference lists, present larger tables, etc. For example, the typical original research article is limited to 2,500 words and 25 references, while the systematic review class allows for 3,500 words and 50 references.

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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.

Verónica Tanco Tellechea

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Cochrane Colloquium Abstracts

Review or original article the manuscript category of systematic review and meta-analysis in high-impact biomedical journals.

Article type Poster Year 2011 Madrid Authors Tam K 1 , Tsai L 2 , K U 3 , Chen C 3 , Lo H 3 1 Department of Surgery and Evidence-based Medicine Center, Taipei Medical University Hospital, Taiwan. Center of Evidence-based Medicine, College of Medicine, Taipei Medical University, Taiwan 2 Evidence-based Medicine Center, Taipei Medical University Hospital, Taiwan 3 Center of Evidence-based Medicine, College of Medicine, Taipei Medical University, Taiwan Abstract Background: Unlike a narrative review, a systematic review involves the application of scientific strategies, in ways that limit bias, to the assembly and critical appraisal of all relevant studies that address a specific clinical question. A meta-analysis is a type of systematic review that uses a statistical strategy for assembling the results of several studies into a single estimate. However, when an author submits a systematic review and meta-analysis to journals, the manuscript category between a review and original article is indistinct. Objectives: To investigate the manuscript category of systematic reviews and meta-analysis in biomedical journals. Methods: Biomedical journals (impact factor >6) that consider systematic reviews and meta-analyses in the field of clinical sciences for publication were included. The Instructions to Authors of biomedical journals and the article category printed on the front page of the literature were reviewed for evidence of an editorial policy on the manuscript category. Results: 63 of 311 biomedical journals publish systematic reviews and meta-analyses of clinical issues. In the Instructions to Authors, 4.76% classified a systematic review and meta-analysis as an original article, 15.9% as a review, 20.6% as an independent type of manuscript, and 58.7% did not mention any policy on the article type for systematic review and meta-analysis. For the article category posted at the front page of the literature, 31.7% printed systematic reviews and meta-analyses as an original article, 9.52% as a review, 4.76% as a meta-analysis, and 39.7% did not reveal the article type on the front page. Conclusions: Most of the high-impact clinical biomedical journals did not mention their policy on classification of systematic reviews and meta-analyses in the Instructions to Authors. However, a relatively large proportion of journals recognize a systematic review and meta-analysis as an original article.

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Review vs. Research Articles

How can you tell if you are looking at a research paper, review paper or a systematic review  examples and article characteristics are provided below to help you figure it out., research papers.

A research article describes a study that was performed by the article’s author(s). It explains the methodology of the study, such as how data was collected and analyzed, and clarifies what the results mean. Each step of the study is reported in detail so that other researchers can repeat the experiment.

To determine if a paper is a research article, examine its wording. Research articles describe actions taken by the researcher(s) during the experimental process. Look for statements like “we tested,” “I measured,” or “we investigated.” Research articles also describe the outcomes of studies. Check for phrases like “the study found” or “the results indicate.” Next, look closely at the formatting of the article. Research papers are divided into sections that occur in a particular order: abstract, introduction, methods, results, discussion, and references.

Let's take a closer look at this research paper by Bacon et al. published in the International Journal of Hypertension :

Review Papers

Review articles do not describe original research conducted by the author(s). Instead, they give an overview of a specific subject by examining previously published studies on the topic. The author searches for and selects studies on the subject and then tries to make sense of their findings. In particular, review articles look at whether the outcomes of the chosen studies are similar, and if they are not, attempt to explain the conflicting results. By interpreting the findings of previous studies, review articles are able to present the current knowledge and understanding of a specific topic.

Since review articles summarize the research on a particular topic, students should read them for background information before consulting detailed, technical research articles. Furthermore, review articles are a useful starting point for a research project because their reference lists can be used to find additional articles on the subject.

Let's take a closer look at this review paper by Bacon et al. published in Sports Medicine :

Systematic Review Papers

A systematic review is a type of review article that tries to limit the occurrence of bias. Traditional, non-systematic reviews can be biased because they do not include all of the available papers on the review’s topic; only certain studies are discussed by the author. No formal process is used to decide which articles to include in the review. Consequently, unpublished articles, older papers, works in foreign languages, manuscripts published in small journals, and studies that conflict with the author’s beliefs can be overlooked or excluded. Since traditional reviews do not have to explain the techniques used to select the studies, it can be difficult to determine if the author’s bias affected the review’s findings.

Systematic reviews were developed to address the problem of bias. Unlike traditional reviews, which cover a broad topic, systematic reviews focus on a single question, such as if a particular intervention successfully treats a medical condition. Systematic reviews then track down all of the available studies that address the question, choose some to include in the review, and critique them using predetermined criteria. The studies are found, selected, and evaluated using a formal, scientific methodology in order to minimize the effect of the author’s bias. The methodology is clearly explained in the systematic review so that readers can form opinions about the quality of the review.

Let's take a closer look this systematic review paper by Vigano et al. published in Lancet Oncology :

Finding Review and Research Papers in PubMed

Many databases have special features that allow the searcher to restrict results to articles that match specific criteria. In other words, only articles of a certain type will be displayed in the search results. These “limiters” can be useful when searching for research or review articles. PubMed has a limiter for article type, which is located on the left sidebar of the search results page. This limiter can filter the search results to show only review articles.

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• Systematic Review | Definition, Examples & Guide

Systematic Review | Definition, Examples & Guide

Published on 15 June 2022 by Shaun Turney . Revised on 18 July 2024.

A systematic review is a type of review that uses repeatable methods to find, select, and synthesise 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, 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 research 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
• Synthesise 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 synthesising all available evidence and evaluating the quality of the evidence. Synthesising means bringing together different information to tell a single, cohesive story. The synthesis can be narrative ( qualitative ), quantitative , or both.

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Systematic reviews often quantitatively synthesise 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 synthesise 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 summarise 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 minimise 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 minimise research b ias by considering all available evidence and evaluating each study for bias.
• Their methods are transparent , so they can be scrutinised by others.
• They’re thorough : they summarise 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 fourth 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
• Randomised 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 synthesise 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.
• Grey literature: Grey 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 grey 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 grey 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
• Grey 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 summarise 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 judgement 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 randomised into the control and treatment groups.

Step 6: Synthesise the data

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

• Narrative ( qualitative ): Summarise the information in words. You’ll need to discuss the studies and assess their overall quality.
• Quantitative : Use statistical methods to summarise 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 analysed 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.

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

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 dissertation , thesis, research paper , or proposal .

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarise yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

Cite this Scribbr article

If you want to cite this source, you can copy and paste the citation or click the ‘Cite this Scribbr article’ button to automatically add the citation to our free Reference Generator.

Turney, S. (2024, July 17). Systematic Review | Definition, Examples & Guide. Scribbr. Retrieved 29 August 2024, from https://www.scribbr.co.uk/research-methods/systematic-reviews/

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Shaun Turney

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Characteristics of a Primary Research Article

• Goal is to present the result of original research that makes a new contribution to the body of knowledge
• Sometimes referred to as an empirical research article
• Typically organized into sections that include:  Abstract, Introduction, Methods, Results, Discussion/Conclusion, and References.

Example of a Primary Research Article:

Flockhart, D.T.T., Fitz-gerald, B., Brower, L.P., Derbyshire, R., Altizer, S., Hobson, K.A., … Norris, D.R., (2017). Migration distance as a selective episode for wing morphology in a migratory insect. Movement Ecology , 5(1), 1-9. doi: doi.org/10.1186/s40462-017-0098-9

Characteristics of a Review Article

• Goal is to summarize important research on a particular topic and to represent the current body of knowledge about that topic.
• Not intended to provide original research but to help draw connections between research studies that have previously been published.  
• Help the reader understand how current understanding of a topic has developed over time and identify gaps or inconsistencies that need further exploration.

Example of a Review Article:

https://www-sciencedirect-com.ezproxy.oswego.edu/science/article/pii/S0960982218302537

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Introduction to Systematic Reviews

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• Tianjing Li 3 ,
• Ian J. Saldanha 4 &
• Karen A. Robinson 5  

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A systematic review identifies and synthesizes all relevant studies that fit prespecified criteria to answer a research question. Systematic review methods can be used to answer many types of research questions. The type of question most relevant to trialists is the effects of treatments and is thus the focus of this chapter. We discuss the motivation for and importance of performing systematic reviews and their relevance to trialists. We introduce the key steps in completing a systematic review, including framing the question, searching for and selecting studies, collecting data, assessing risk of bias in included studies, conducting a qualitative synthesis and a quantitative synthesis (i.e., meta-analysis), grading the certainty of evidence, and writing the systematic review report. We also describe how to identify systematic reviews and how to assess their methodological rigor. We discuss the challenges and criticisms of systematic reviews, and how technology and innovations, combined with a closer partnership between trialists and systematic reviewers, can help identify effective and safe evidence-based practices more quickly.

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What Is the Difference Between a Systematic Review and a Meta-analysis?

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Tianjing Li

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Li, T., Saldanha, I.J., Robinson, K.A. (2022). Introduction to Systematic Reviews. In: Piantadosi, S., Meinert, C.L. (eds) Principles and Practice of Clinical Trials. Springer, Cham. https://doi.org/10.1007/978-3-319-52636-2_194

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About Systematic Reviews

A Peer Review vs a Systematic Review

Automate every stage of your literature review to produce evidence-based research faster and more accurately.

Learn More In a sea of existing scientific literature, the rate at which new articles and reviews are being published is skyrocketing. So how does one know with all this available literature which studies are credible and relevant? This is where the different review types come into play. Each of the review types addresses scientific questions in its own unique manner. With evidence-based medicine gaining popularity, there is a need to produce high-quality scientific articles to guide clinical practice. This has led to the emergence of evidence synthesis which attempts to identify, collect and analyze results from multiple sources. Evidence synthesis is described as the interpretation of information contained in individual studies within the scope of the research topic. Systematic reviews are the most effective forms used to conduct evidence synthesis since they use rigorous, methodical, and reproducible processes. But there is a difference between evidence synthesis and a systematic review , so be sure you have a clear understanding of them. Evidence synthesis methods also comprise other types of reviews such as scoping reviews, narrative reviews, meta-analyses, and rapid reviews. If you’d like to know more about the differences between a rapid review vs systematic review , you can read on at the link.

In this article, we will look at what a systematic review is , and how it is different from a peer review.

What Is A Systematic Review?

A systematic review uses explicit methods to identify, select, and critically appraise relevant primary research. It attempts to review all the available evidence to answer a clearly formulated research question. Systematic reviews use inclusion or eligibility criteria to filter out studies irrelevant to the search topic. They are hallmarks of the evidence synthesis process in scientific research since they use all eligible existing research on a topic. Unlike research papers like RCTs that report primary data, systematic reviews report on the findings by combing primary information extracted from eligible studies. This makes systematic reviews a secondary report of data. The methodology involved is rigorous, transparent, and reproducible, this makes systematic reviews a high-quality source of information.

The Systematic review methodology involves the following steps.

• Formulating and stating a clear research question to answer (PICO approach)
• Developing a protocol (with strict inclusion and exclusion criteria for the selection of primary studies)
• Performing a detailed and broad literature search
• Critical appraisal of the selected studies
• Data extraction from the primary studies included in the review
• Data synthesis and analysis using qualitative or quantitative methods [1].

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(Article continues below)

What Is A Peer Review?

Peer review is a system to assess the quality of a manuscript submitted by the author before it is published. Independent researchers in the same discipline assess the manuscripts for originality, quality, validity, and significance to help editors determine if they can be published in their journal. Based on the quality score awarded by the reviewers, the manuscript may be forwarded to a more fitting journal. For example, high-quality manuscripts are forwarded to high-quality journals, this leads to categories called journal classes. These independent reviewers may or may not have competencies similar to the authors of the manuscript.

How Does A Peer Review Work?

When a manuscript or an article is submitted to a journal, it is assessed by the editor to see if it meets the criteria for submission. Once it is confirmed that it satisfies the criteria, the editorial team then selects potential peer reviewers within the same field to evaluate the manuscript.

Single-blind, double-blind, or open reviewing, are techniques used to assess the originality, quality, validity, and significance of the manuscript. A variation from these standard approaches is the transparent, collaborative, and post-publication peer reviews.

Different journals use any of these methods to evaluate the quality of the content they publish. You can find out which peer-review system is used by a particular journal on their “about” page.

Why Do We Need A Peer Review?

Peer reviews are designed to assess the validity, quality, and originality of scientific articles that are published. This helps in maintaining the integrity of scientific literature by filtering out poor articles. Peer reviewers are experts in a certain field who volunteer their time to help improve the quality of manuscripts that are published. They help point out gaps in articles that may require further explanation and suggest changes to make a paper easier to read, and more useful in the field.

Researchers mustn’t confuse these two types of reviews. A systematic review involves reviewing all the available eligible literature to find credible, and reliable evidence to answer a specific research question. A peer review, on the other hand, is done by other authors in the same discipline and evaluates the quality, validity, and originality of a single article before it is published. The process of peer review establishes confidence in the articles that are published in a journal. Systematic reviews then search for and collect studies that have been peer-reviewed, to synthesize evidence found in them. Systematic reviews, after their completion by the author, are also peer-reviewed before publication.

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Empirical Journal Articles

Empirical Article - (Original Research) Based on experience and observation, rather than systematic logic. (according to MedicineNet.com)

The articles contain original research (such as scientific experiments, surveys and research studies) A list of references or sources is provided at the end of each article An editorial board, composed of experts in the field, reviews articles to decide whether they should be accepted; this is also known as "refereed," "peer-reviewed," "professional," "scholarly", or "academic". Uses a specialized vocabulary for that field.

Below are two websites that explain Empirical articles and research:

Empirical Research: How to Recognize and Locate (Penn State University) - Empirical Research PDF

Review Journal Articles

Review Article

An article that summarizes the progress or current state in some particular subject, area, or topic.

How to write a "Review Article?" (National Library of Medicine) - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4548566/

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Editorial: Review Articles, Systematic Reviews, Meta-Analysis, and the Updated Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 Guidelines

Subjective narrative review articles have an educational and informative role in medical and scientific journals. Systematic review of the literature requires an objective and complete review of all available publications on an identified topic. Systematic review that undergoes meta-analysis aims to provide a complete and objective evaluation of all the published data. Data from systematic review and meta-analysis publications support evidence-based medical practice and are prepared as original research articles. These studies require a clear aim and detailed planning with registration and approval of the study protocol before the study commences. Systematic review and meta-analysis studies are designed, conducted, and reported according to mandatory guidelines. The number of these publications has continued to rise during the past decade. However, concerns with the quality of the studies have resulted in more stringent study guidelines. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, guidelines, reporting checklist, and study flow diagram from 2009 were updated and published in March 2021 as PRISMA 2020. The Editorial aims to present the roles and requirements of subjective narrative review articles, systematic review of the literature, and systematic review and meta-analysis, and introduces the revisions and aims of the PRISMA 2020 guidelines.

In 2006, a former Editor of the British Medical Journal (BMJ) commented that medical journals represent ‘ a confluence of medicine, science, and journalism ’ [ 1 ]. The narrative review article contains these three elements to provide a balanced view without the conflicting or sensational style of modern journalism, with a subjective approach, but with all statements supported with reference citations [ 1 , 2 ]. Medical and life sciences journals publish review articles that are usually narrative reviews written subjectively by the author to support an area of medical research, a clinical topic, or a hypothesis [ 3 ]. Because of the subjective nature of review articles, there is no expectation that all publications on the topic are cited [ 4 ]. However, there is an expectation that the review’s aims are made clear in the publication title, abstract, and introduction [ 3 , 4 ]. All statements made by the authors are supported by key references and with a clear conclusion [ 3 , 4 ]. Key researchers or senior clinicians write some invited review articles to overview recent developments, research, and clinical guidelines [ 4 ]. For all these reasons, review articles still have an educational and informative role [ 3 , 4 ].

In contrast to a narrative review article, a systematic review of the literature should focus on a specific and clearly defined topic and include all the eligible published studies, without subjective selection by the author [ 5 , 6 ]. Systematic reviews have been increasingly published to provide evidence from all the available published data to improve clinical decisions in medicine [ 5 , 6 ]. However, even large clinical trials may not provide sufficient answers to a clinical question [ 7 ]. The findings from a systematic review of the literature from previously published studies may support or refute the findings or identify deficiencies in the trial design [ 8 ]. Without meta-analysis, a systematic review of the literature is most applicable for questions that require answering without quantitative data, such as how and why a therapeutic intervention may improve an aspect of medicine or health that is not quantifiable [ 6 ]. Also, some studies are too different to combine for quantitative analysis, such as how several varieties of non-standard treatment combinations may improve a subjective clinical outcome [ 6 ].

Evidence-based medicine and clinical practice rely on evidence from the medical literature, clinical training, expertise, and experience to provide high standards of patient care [ 8 ]. Systematic review combined with meta-analysis of the data from all the published evidence is considered the gold standard to support evidence-based clinical decisions [ 8 ]. There is still widespread confusion from authors regarding the difference between systematic reviews and systematic review and meta-analysis, which may be believed to be the same. The word meta-analysis means a ‘study about studies.’ A meta-analysis study is a formal, quantitative method used to assess specific published research findings [ 9 ]. Usually, a meta-analysis study is based on published randomized, controlled clinical trials but may include cohort studies, case-control studies, or preclinical studies [ 9 ]. Meta-analysis that combines and analyses the numerical data from multiple separate studies should only be used with systematic literature review and represent original research articles [ 9 ]. Systematic review and meta-analysis are methods that combine to synthesize all the available evidence, including the strengths and weaknesses of the identified studies, the study populations, the interventions used, and the specific study outcomes assessed in each study [ 9 ].

Clinicians may make decisions from the findings of systematic review and meta-analysis. Because these studies should be conducted objectively as original research studies, guidelines for the conduct and reporting of these studies have been published [ 9 ]. In 2009, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and guidelines were published for study conduct and reporting, including a reporting checklist [ 9 ]. These PRISMA guidelines helped to establish eight main considerations for authors before undertaking a systematic review and meta-analysis, which included: define the question of the review; write and publish or register the study protocol; undertake an objective and complete systematic review of the literature; identify the included studies by screening the results against the study selection criteria; undertake an appraisal of the quality of the studies; synthesize the evidence of the study using meta-analysis; prepare a manuscript for publication according to the reporting guidelines; update the systematic review and meta-analysis as new data is published [ 9 , 10 ].

A common reason for the rejection of submitted manuscripts that present systematic review and meta-analysis studies is the lack of suitability of the review topic. This problem highlights the importance of approving study protocols before conducting a systematic review and meta-analysis [ 9 ]. Therefore, study protocols for systematic review and meta-analysis should be prepared in advance and registered and approved by either PROSPERO or Cochrane [ 9 ]. The International Prospective Register of Systematic Reviews (PROSPERO) ( www.crd.york.ac.uk/prospero/ ) has been available since 2011 with the aim of increasing the transparency of systematic reviews [ 11 ]. The Cochrane Review is a systematic review of research in health care and health policy published in the Cochrane Database of Systematic Reviews (CDSR) [ 12 , 13 ].

Increasing numbers of systematic reviews compare multiple treatments, often with indirect comparisons, resulting in new challenges for conducting and reporting systematic reviews incorporating network meta-analyses [ 14 ]. In 2015, the PRISMA extension statement was published with guidelines for conducting and reporting network meta-analysis (NMA) studies [ 15 ]. The modified 32-item PRISMA extension checklist, or PRISMA-NMA checklist, was also developed to include the main requirements for reporting network meta-analyses and modifications of previously existing items from the PRISMA statement [ 16 ].

The number of published systematic review and meta-analysis studies has increased during the past decade, but the quality has declined [ 17 ]. In 2018, a review of publication trends from PubMed from 1995 to 2015 showed that although the USA leads in all publication citations and specific publication types, meta-analysis studies were mainly published by authors from China [ 17 ]. In the hierarchy of published evidence in medicine and medical research, randomized controlled trials, systematic reviews, and meta-analysis studies are at the top of the evidence standards [ 8 , 17 ]. Increasingly, meta-analysis and review articles have become some of the most highly cited publications [ 18 ]. However, the exponential rise in the number of meta-analysis studies has raised concerns regarding the quality and reproducibility of meta-analysis publications [ 19 ]. Systematic review and meta-analysis publications inform clinical practice, often when there are no available data from controlled clinical trials. For this reason, the quality of published systematic review and meta-analysis studies, rather than the quantity, should be as high as possible [ 8 ].

On March 29, 2021, the updated Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 Statement was published [ 20 ]. PRISMA 2020 now replaces PRISMA 2009 for conducting and reporting systematic reviews and meta-analysis studies [ 20 ]. The 2020 PRISMA guidelines include a 27-item reporting checklist, a study flow diagram, and an explanation and elaboration document [ 20 ]. The PRISMA 2020 expanded checklist for reporting systematic review and meta-analysis summarizes the requirements for the publication title, abstract, introduction, rationale, and objectives [ 21 ]. The PRISMA 2020 expanded checklist includes main subsections required in the main Methods section of the publication, which includes: the eligibility criteria of the selected studies; information sources; search strategy; selection process; data collection process; data items; assessment of the risk of bias; effect measures; synthesis methods; assessment of reporting bias; and certainty assessment [ 21 ]. The PRISMA 2020 expanded checklist includes main subsections required in the main Results section of the publication, which includes: study selection; study characteristics; risk of bias in the selected studies; results of individual studies; results of study synthesis; reporting bias; and certainty of evidence [ 21 ]. The PRISMA 2020 guidelines and reporting checklist make the registration of the study protocol mandatory [ 20 , 21 ]. Modifications included in PRISMA 2020 also require authors to present full search strategies for all databases, registers, and websites searched, how many reviewers screened each record, and how outcomes were defined [ 20 ]. A new item in PRISMA 2020 requires authors to indicate whether the data, analytic codes and other methods and findings used in the systematic review are publicly available and where they can be found [ 20 ]. PRISMA 2020 also includes an expanded checklist and a PRISMA 2020 flow diagram template for systematic reviews [ 22 , 23 ].

Conclusions

Subjective narrative review articles have an educational and informative role in medical and scientific journals. However, systematic review of the literature requires an objective and complete review of all available publications on a clearly defined topic. Systematic review that undergoes meta-analysis aims to provide a complete and objective evaluation of all the published data on a specific topic and the findings are the basis of evidence-based clinical practice. In the past decade, the exponential rise in systematic review and meta-analysis study publications has raised concerns regarding the quality and reproducibility of meta-analysis data and study findings. For this reason, the updated PRISMA 2020 guidelines and checklist, published in March 2021, have been developed to improve the conduct and reporting of systematic review and meta-analysis studies.

Conflict of interest: None declared