The PRISMA 2020 guidelines are the current international standard for reporting systematic reviews and meta-analyses. Published by Page et al. in 2021, the PRISMA 2020 statement replaced the original PRISMA 2009 guidelines that had governed systematic review reporting for over a decade. Every researcher conducting a systematic review must understand these guidelines, not as an afterthought during manuscript preparation, but as a framework that shapes the entire review process from protocol to publication.
In every systematic review we deliver, PRISMA 2020 compliance is our baseline, not an optional extra. Having prepared hundreds of PRISMA-compliant manuscripts, we have seen firsthand how adherence to these reporting standards reduces desk rejections, satisfies peer reviewers, and accelerates the path to publication.
What Are the PRISMA 2020 Guidelines?
PRISMA stands for Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The PRISMA 2020 statement (Page et al., 2021) is a reporting guideline, not a methodological guide, that specifies the minimum information authors should include when reporting a systematic review. It was developed by an international group of systematic review methodologists, journal editors, and other stakeholders, and is endorsed by the EQUATOR Network (Enhancing the QUAlity and Transparency Of health Research) as the definitive reporting standard for this study design.
The distinction between a reporting guideline and a methodological guide matters. PRISMA 2020 does not tell you how to conduct a systematic review. It tells you what to report about how you conducted one. The Cochrane Handbook for Systematic Reviews of Interventions (Higgins et al., 2023) provides methodological guidance; PRISMA 2020 ensures that the methods you used are communicated transparently to readers, peer reviewers, and editors.
PRISMA 2020 applies to systematic reviews of interventions, exposures, diagnostic test accuracy, prognosis, and other research questions. It applies whether or not the review includes a meta-analysis. The guidelines are relevant across disciplines, from medicine and public health to psychology, education, and environmental science, wherever systematic reviews are conducted and published.
The EQUATOR Network maintains PRISMA 2020 as part of its library of reporting guidelines and recommends its use by authors, editors, and peer reviewers worldwide. Journals that endorse EQUATOR guidelines, which includes the majority of biomedical journals indexed in MEDLINE, expect submitted systematic reviews to comply with PRISMA 2020.
The 27 Checklist Items Explained
The PRISMA 2020 checklist contains 27 items organized across seven sections. Each item specifies a reporting element that should be present in your manuscript, with the corresponding section (title, abstract, introduction, methods, results, discussion, or other information) indicating where the information belongs.
Section 1: Title (Item 1)
Item 1, Title: Identify the report as a systematic review. The title must explicitly state that the manuscript is a systematic review, a meta-analysis, or both. Titles that describe the topic without identifying the study design fail this item. A compliant title reads something like "Effectiveness of cognitive behavioral therapy for insomnia: a systematic review and meta-analysis" rather than simply "Cognitive behavioral therapy for insomnia."
Section 2: Abstract (Item 2)
Item 2, Abstract: Provide a structured summary including background, objectives, data sources, study eligibility criteria, participants, interventions, study appraisal and synthesis methods, results, limitations, conclusions, and registration information. Most journals require structured abstracts for systematic reviews, and PRISMA 2020 specifies what each section should contain.
Section 3: Introduction (Items 3-4)
Item 3, Rationale: Describe the rationale for the review in the context of existing knowledge. This means explaining why the review is needed, whether previous reviews are outdated, conflicting, or nonexistent.
Item 4, Objectives: Provide an explicit statement of the review question using the PICO framework (Population, Intervention, Comparator, Outcome) or an appropriate alternative.
Section 4: Methods (Items 5-16)
The methods section contains 12 items, nearly half the entire checklist, reflecting PRISMA 2020's emphasis on methodological transparency. This is where most reporting failures occur, and where compliance matters most for peer review.
Item 5, Eligibility criteria: Specify the inclusion and exclusion criteria for the review, including study characteristics (PICO elements) and report characteristics (publication date, language, publication status).
Item 6, Information sources: Describe all information sources searched, including databases, registers, websites, organizations, and reference lists. Specify the date of the last search for each source.
Item 7, Search strategy: Present the complete search strategy for at least one database, including any filters and limits, so that it can be reproduced. This is a new emphasis in PRISMA 2020, full reproducibility of the search.
Item 8, Selection process: Specify the methods used to decide whether a study meets the eligibility criteria, including how many reviewers screened each record and each report, whether they worked independently, and what software or automation tools were used.
Item 9, Data collection process: Specify the methods used to collect data from reports, including how many reviewers collected data, whether they worked independently, any processes for obtaining or confirming data from study investigators, and any automation tools used.
Item 10, Data items: List and define all outcomes and other variables for which data were sought, specifying any assumptions and simplifications made.
Item 11, Study risk of bias assessment: Specify the methods used to assess risk of bias in included studies, including which tool was used (such as RoB 2 for randomized trials or ROBINS-I for non-randomized studies), how many reviewers assessed each study, and whether they worked independently.
Item 12, Effect measures: Specify for each outcome the effect measure used (risk ratio, odds ratio, mean difference, etc.) and how it was calculated.
Item 13, Synthesis methods: Describe the processes used to synthesize results, including the statistical model (fixed-effect or random-effects), the method for calculating the summary effect, methods for assessing heterogeneity (such as I-squared and tau-squared), any sensitivity analyses, and subgroup analyses planned a priori. This item also covers narrative synthesis approaches when meta-analysis is not possible.
Item 14, Reporting bias assessment: Describe any methods used to assess the risk of reporting bias across studies, such as funnel plots, Egger's test, or trim-and-fill analysis.
Item 15, Certainty assessment: Describe any methods used to assess certainty (or confidence) in the body of evidence for each outcome, such as the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) approach. This is a new requirement in PRISMA 2020 that was not present in the 2009 version.
Item 16, Study registration and protocol: Provide registration information for the review, including the register name and registration number, and indicate where the review protocol can be accessed. If a protocol was prepared, indicate where it can be accessed and list any amendments to the protocol.
Section 5: Results (Items 17-23)
Item 17, Study selection: Give the total number of records identified, screened, assessed for eligibility, and included, with reasons for exclusion at each stage. This information is presented in the PRISMA flow diagram.
Item 18, Study characteristics: Cite each included study and present its characteristics, including the PICO elements, study design, sample size, and funding source.
Item 19, Risk of bias in studies: Present the results of the risk of bias assessment for each included study and across studies for each outcome.
Item 20, Results of individual studies: For all outcomes, present for each study a summary of the data, the effect estimate with confidence interval, and any supporting visual display such as a forest plot.
Item 21, Results of syntheses: For each synthesis, present the summary result with confidence interval and measures of statistical heterogeneity. Present any assessments of heterogeneity causes (subgroup analyses, meta-regression). If meta-analysis was not conducted, present structured summaries of the individual study results.
Item 22, Reporting biases: Present any assessments of risk of reporting bias, including results of funnel plots or statistical tests.
Item 23, Certainty of evidence: Present assessments of certainty in the body of evidence for each outcome assessed, typically using GRADE summary of findings tables.
Section 6: Discussion (Items 24-26)
Item 24, Discussion: Provide a general interpretation of results in the context of other evidence. Discuss the limitations of the evidence included in the review and limitations of the review process itself.
Item 25, Implications: Discuss implications for practice, policy, and future research.
Item 26, Other information: Provide information about sources of financial or non-financial support for the review, declare any conflicts of interest, and state the availability of data, code, and other materials used in the review.
Section 7: Other Information (Item 27)
Item 27, Registration and protocol: Provide the registration number and where the registration and protocol can be accessed. While this overlaps with Item 16 in the methods, Item 27 ensures this information is also presented in the final sections of the manuscript for quick reference.
Changes from PRISMA 2009 to PRISMA 2020
Understanding what changed between the two versions is critical for researchers who learned systematic review methods using the 2009 statement. The following table summarizes the major differences.
| Feature | PRISMA 2009 | PRISMA 2020 |
|---|---|---|
| Number of items | 27 items | 27 items (but content substantially revised) |
| Protocol registration | Recommended but not a specific item | Dedicated item (Item 16) requiring registration details |
| Search strategy | Present for at least one database | Present for all databases, with emphasis on full reproducibility |
| Automation tools | Not addressed | Requires reporting of any automation or machine learning tools used in screening, data extraction, or risk of bias assessment |
| Certainty of evidence | Not a specific item | Dedicated item (Item 15/23) requiring GRADE or equivalent assessment |
| Flow diagram phases | Three phases (identification, screening, included) | Four phases (identification, screening, eligibility, included) with separate tracking for databases/registers versus other methods |
| Data items | Describe data items | List and define all outcomes and variables with assumptions |
| Reporting bias | Describe and present results | Expanded to include specific methods and tools |
| Abstract structure | Structured summary | More detailed requirements for abstract content |
| Amendments to protocol | Not required | Must describe any amendments to the registered protocol |
| Software and tools | Not addressed | Requires reporting of review management software and any automation |
| Funding sources | Included studies funding not required | Requires reporting funding sources for both the review and included studies |
Four items in PRISMA 2020 are entirely new compared to 2009: protocol registration and amendments, certainty of evidence assessment, reporting of automation tools, and expanded data availability statements. Additionally, several items from 2009 were split, merged, or substantially reorganized to improve clarity and completeness.
The most visible change is the redesigned flow diagram, which now has four distinct phases and separately tracks records identified through database searching versus those identified through other methods such as citation searching, grey literature, or expert consultation.
The PRISMA 2020 Flow Diagram
The PRISMA flow diagram is perhaps the most recognizable element of PRISMA reporting. The 2020 version introduces a substantially redesigned diagram that provides greater transparency about the identification, screening, and inclusion process.
The updated flow diagram contains four phases:
Phase 1, Identification: Records are identified from two streams. The first stream captures records identified through database searching (e.g., MEDLINE, Embase, CINAHL) and register searching (e.g., ClinicalTrials.gov, PROSPERO). The second stream captures records identified through other methods, including citation searching, grey literature searching, and contacting experts. Duplicates are removed within each stream before proceeding to screening.
Phase 2, Screening: Records remaining after duplicate removal are screened by title and abstract. Records excluded at this stage are counted and the total is reported. Records marked as ineligible by automation tools (if used) are reported separately.
Phase 3, Eligibility: Reports sought for retrieval are assessed. Any reports not retrieved are counted. Retrieved reports are assessed for eligibility against the inclusion criteria, and excluded reports are counted with reasons for exclusion categorized and reported.
Phase 4, Included: The final number of studies and reports included in the review is presented. If the review includes both new studies and studies from a previous version of the review, these are reported separately.
The arithmetic must be consistent throughout the diagram. The number of records at each stage must reconcile, records identified minus duplicates removed must equal records screened, and so on through each phase. Our free PRISMA flow diagram generator automates this arithmetic to prevent errors that frequently occur in manually constructed diagrams.
A correctly completed flow diagram demonstrates the transparency of your search and selection process at a glance. Peer reviewers examine it closely, checking for arithmetic consistency and adequate documentation of exclusion reasons. Missing or inconsistent flow diagrams are among the most common reasons for revision requests in systematic review manuscripts.
How to Use the PRISMA 2020 Checklist
Using the PRISMA 2020 checklist effectively requires integrating it into your workflow from the earliest stages of your review, not treating it as a post-hoc documentation exercise. Here is a practical approach based on our experience preparing PRISMA-compliant manuscripts.
Start at the protocol stage. Before you begin your review, download the PRISMA 2020 checklist and familiarize yourself with every item. Use PRISMA-P (Preferred Reporting Items for Systematic review and Meta-Analysis Protocols) to guide your protocol, then transition to PRISMA 2020 for the final manuscript. This two-stage approach ensures continuity from protocol to publication.
Complete items as you write each section. As you draft each section of your manuscript, open the corresponding checklist items and verify that you have included the required information. For the methods section, this means checking Items 5 through 16 as you write your eligibility criteria, information sources, search strategy, and synthesis methods. Do not wait until the manuscript is complete, by then, gaps are harder to fill.
Record page and line numbers. The PRISMA 2020 checklist includes a column for recording the page number where each item is reported. Fill this column as you write. When you submit the checklist as supplementary material (as most journals require), editors and reviewers can immediately locate each item in your manuscript.
Use the expanded checklist for meta-analyses. If your review includes a meta-analysis, pay special attention to Items 13a-13f (synthesis methods) and Items 20-22 (results of individual studies, syntheses, and reporting biases). These items require detailed reporting of statistical models, heterogeneity measures, and any quantitative sensitivity or subgroup analyses.
Verify flow diagram consistency. Before submission, independently verify that every number in your flow diagram is arithmetically consistent. The most common errors are: duplicates removed not reconciling with records screened, exclusion reasons not summing to total exclusions, and mismatches between full-text screening numbers and eligibility assessment totals.
Address not-applicable items. If a checklist item does not apply to your review, for example, reporting bias assessment when you have fewer than 10 studies, explicitly state that the item is not applicable and explain why. Leaving items blank suggests omission rather than intentional exclusion.
PRISMA Extensions: ScR, DTA, NMA, and PRISMA-P
PRISMA 2020 is the core statement for systematic reviews of interventions and exposures, but several extensions address specific review types that require additional or modified reporting items.
PRISMA-ScR (Scoping Reviews): Published by Tricco et al. (2018), PRISMA-ScR provides a 22-item checklist specifically designed for scoping reviews. Scoping reviews differ from systematic reviews in purpose (mapping evidence rather than answering a specific question), methodology (broader inclusion criteria, no risk of bias assessment), and output (descriptive rather than quantitative synthesis). Using PRISMA 2020 for a scoping review is incorrect, use PRISMA-ScR instead. Our PRISMA-ScR checklist guide provides a detailed walkthrough of each item, and our free PRISMA-ScR checklist tool helps you track compliance.
PRISMA-DTA (Diagnostic Test Accuracy): PRISMA-DTA extends the core PRISMA statement for systematic reviews of diagnostic test accuracy studies. These reviews have unique methodological requirements, paired forest plots of sensitivity and specificity, summary ROC curves, and quality assessment using QUADAS-2, that the standard PRISMA checklist does not adequately address.
PRISMA-NMA (Network Meta-Analysis): Network meta-analyses compare multiple interventions simultaneously using both direct and indirect evidence. PRISMA-NMA extends the reporting requirements to cover network geometry, transitivity assessment, ranking of interventions, and the presentation of network diagrams and contribution matrices.
PRISMA-P (Protocols): PRISMA-P provides a 17-item checklist for systematic review protocols. Using PRISMA-P at the protocol stage and PRISMA 2020 at the reporting stage creates a complete documentation chain from planning through publication. PRISMA-P covers items specific to protocols, such as the planned timeline, team roles, and amendments procedures, that are not relevant in the final manuscript report.
PRISMA-S (Search Reporting): PRISMA-S is a more recent extension that elaborates on the search reporting requirements within PRISMA 2020 Item 7. It provides a 16-item checklist specifically for documenting the search strategy, including database selection rationale, search validation, and peer review of the search (using tools such as PRESS, Peer Review of Electronic Search Strategies).
Each extension is maintained by the EQUATOR Network and updated independently. Researchers should identify which PRISMA extension applies to their specific review type before beginning the manuscript, as retrofitting compliance is more difficult and error-prone than building it in from the start.
Common PRISMA 2020 Compliance Mistakes
After reviewing hundreds of systematic review manuscripts, we consistently observe the same compliance failures. Avoiding these common mistakes will strengthen your manuscript and reduce the likelihood of revision requests.
Incomplete search strategy reporting. Item 7 requires the full search strategy for at least one database, including every search term, Boolean operator, field tag, and filter. Many authors provide only a summary or list of keywords. Reviewers who cannot reproduce your search will question the comprehensiveness of your identification process.
Missing or inconsistent flow diagram. The flow diagram is often constructed hastily at the end of the writing process, leading to arithmetic errors. Numbers that do not reconcile across phases signal carelessness to reviewers. Use our PRISMA flow diagram generator to eliminate arithmetic inconsistencies.
No protocol registration. Item 16 requires reporting of protocol registration details. Reviews that were not prospectively registered should acknowledge this as a limitation. Journals increasingly expect PROSPERO registration for systematic reviews, and failure to register, or failure to report registration, weakens the manuscript.
Omitting certainty of evidence assessment. PRISMA 2020 Items 15 and 23 require that authors describe their method for assessing certainty of evidence (typically GRADE) and present the results. This was not required in PRISMA 2009, and many researchers trained on the earlier version overlook it. The GRADE approach assesses the certainty of evidence across five domains: risk of bias, inconsistency, indirectness, imprecision, and publication bias.
Incomplete risk of bias reporting. Item 11 requires specification of the risk of bias tool used, and Item 19 requires presentation of results for each study and each outcome. Presenting only a summary table without individual study assessments is insufficient. Individual study-level risk of bias results, ideally in a traffic-light plot or summary figure, are expected.
Ignoring reporting bias assessment. Items 14 and 22 address reporting bias, the systematic non-publication or selective reporting of study results. When 10 or more studies are included in a meta-analysis, funnel plots and statistical tests (Egger's test, Begg's test) should be reported. When fewer than 10 studies are included, authors should explain why these assessments were not conducted rather than simply omitting them.
Vague exclusion reasons. Item 17 and the flow diagram require reasons for exclusion at the full-text screening stage. Reasons such as "did not meet inclusion criteria" are uninformative. Specific reasons, wrong population, wrong intervention, wrong outcome, wrong study design, wrong publication type, allow readers to assess whether potentially relevant studies were inappropriately excluded.
Failing to report automation tools. PRISMA 2020 explicitly requires reporting of any automation or machine learning tools used during the review process. If you used Covidence, Rayyan, ASReview, or any other tool for screening, data extraction, or risk of bias assessment, this must be reported. Many researchers use these tools but neglect to mention them in the manuscript.
PRISMA 2020 and Journal Requirements
Understanding how journals enforce PRISMA 2020 helps researchers prepare manuscripts that pass editorial screening on the first submission. The relationship between PRISMA 2020 and journal requirements determines whether compliance is advisory or mandatory for your target publication.
Most biomedical journals indexed in MEDLINE endorse the EQUATOR Network reporting guidelines, which means they expect, and many explicitly require, PRISMA 2020 compliance for submitted systematic reviews. Journals such as The BMJ, The Lancet, JAMA, and Annals of Internal Medicine require a completed PRISMA checklist as supplementary material at submission. Cochrane Reviews follow an adapted version of PRISMA 2020 integrated into the Cochrane format.
Some journals conduct formal PRISMA compliance checks during editorial screening, rejecting manuscripts that fail to meet minimum reporting standards before they even reach peer review. This desk rejection can be avoided entirely by ensuring PRISMA 2020 compliance before submission.
Even journals that do not formally require the checklist will evaluate your manuscript against PRISMA standards during peer review. Reviewers trained in systematic review methodology use PRISMA as their assessment framework, and missing items will appear as revision requests. Proactive compliance eliminates these preventable revision rounds.
For researchers targeting high-impact journals, PRISMA 2020 compliance signals methodological rigor and familiarity with current reporting standards. Combined with prospective protocol registration in PROSPERO and adherence to the Cochrane Handbook methodology, PRISMA compliance positions your manuscript competitively for journals that receive far more submissions than they can publish.
Our guide to writing a systematic review step by step covers how PRISMA 2020 integrates with the broader systematic review workflow, from formulating the research question through submission. And for researchers who want professional support with PRISMA-compliant manuscript preparation, our systematic review writing service delivers completed manuscripts with full PRISMA 2020 checklists, flow diagrams, and risk of bias assessments ready for journal submission.