PRISMA 2020 Checklist: The 27 Items Explained
By Dr. Zubair Khalid, DVM, MS, PhD ·
Quick Answer
- Use the PRISMA 2020 checklist as your reporting map for systematic reviews, covering title, abstract, introduction, methods, results, discussion, and funding information.
- Work through all 27 items systematically before submission, because journals and funders increasingly require transparent reporting against established guidelines.
- The checklist verifies what you report, not how you conducted the review, so poor search methods can still pass PRISMA checks.
What PRISMA 2020 Is and Why It Matters
PRISMA 2020 stands for Preferred Reporting Items for Systematic Reviews and Meta-Analyses. It is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses. The EQUATOR Network maintains a comprehensive library of reporting guidelines and promotes transparent and accurate research reporting across health and life sciences.
Systematic reviews answer focused research questions by identifying, evaluating, and synthesizing all relevant studies. Unlike narrative reviews, systematic reviews follow a predefined protocol with explicit search strategies, inclusion criteria, and quality assessments. The PRISMA 2020 checklist helps you document each step so readers can judge the reliability of your conclusions.
Researchers face a practical problem: journals and funders now expect systematic reviews to meet reporting standards. When you submit a manuscript, reviewers check whether you have reported essential elements such as your search strategy, study selection process, risk of bias assessment, and synthesis methods. Missing items trigger revision requests or outright rejection.
The PRISMA 2020 statement updated the original 2009 version to address advances in systematic review methodology. It includes new items for searching databases and registers, reporting synthesis methods, and assessing certainty of evidence. The checklist applies to systematic reviews that include randomized trials and reviews that include non-randomized studies.
At a Glance
| PRISMA Section | What You Report | Common Mistake |
|---|---|---|
| Title and Abstract | Identify the report as a systematic review and provide a structured summary | Omitting the systematic review label from the title |
| Introduction | State objectives and specify the research question with PICO elements | Writing broad objectives without a focused question |
| Methods | Report eligibility criteria, information sources, search strategy, selection process, data collection, risk of bias, effect measures, synthesis methods, and certainty assessment | Describing the search without giving the full strategy or date |
| Results | Show study selection flow, study characteristics, risk of bias results, synthesis results, and reporting biases | Presenting only final included studies without the screening numbers |
| Discussion | Interpret results in context, discuss limitations of evidence and review process | Ignoring limitations of the included studies |
| Other Information | Report registration, protocol, funding, and conflicts of interest | Failing to state whether a protocol was registered |
Core Principles of Transparent Reporting
Reporting versus Conduct
PRISMA 2020 evaluates how completely you report your systematic review, not how well you conducted it. A review with a weak search strategy can still satisfy PRISMA if you describe that weak strategy accurately. Conversely, a methodologically excellent review fails PRISMA if you omit key details. This distinction matters because the checklist serves readers who need to assess validity and reproducibility.
The Committee on Publication Ethics core practices emphasize transparency in research publication. These practices cover authorship, duplicate submission, data access, ethical oversight, and conflicts of interest. When you report a systematic review, you should align with these ethical expectations by disclosing all relevant information about how the review was planned and executed.
Reproducibility as the Goal
A complete PRISMA-compliant report allows another researcher to replicate your review. Reproducibility requires that you document your search strings, database platforms, date restrictions, language limits, and screening decisions. If another team cannot reconstruct your search and selection process, your review lacks the transparency that PRISMA promotes.
The National Library of Medicine hosts research methods resources that explain systematic review methodology in depth. These resources describe how to develop search strategies, manage citations, extract data, and assess risk of bias. You can use these materials to understand what each PRISMA item expects before you write your manuscript.
The 27 PRISMA 2020 Items Explained
Title and Abstract Items
Item 1: Title. Identify the report as a systematic review, meta-analysis, or both. The title should let readers immediately recognize the study design. For example, "Efficacy of X for Treating Condition Y: A Systematic Review and Meta-Analysis" clearly signals the review type.
Item 2: Abstract. Provide a structured summary that covers background, objectives, methods, results, discussion, funding, and registration. The abstract should stand alone because many readers access only the abstract through databases. Include the number of included studies, participant totals, main effect estimates, and key limitations.
Introduction Items
Item 3: Rationale. Describe the rationale for the review in the context of existing knowledge. Explain why the question matters and what gap the review addresses. This section connects your review to prior research and justifies the effort.
Item 4: Objectives. Provide an explicit statement of the objective or question the review addresses. Use the PICO framework (Population, Intervention, Comparator, Outcomes) or an appropriate alternative for your review type. A focused question guides your search strategy and eligibility criteria.
Methods Items
Item 5: Eligibility Criteria. Specify the inclusion and exclusion criteria for the review and how studies were grouped for syntheses. Report population characteristics, intervention types, comparators, outcomes, study designs, and setting restrictions. Justify each criterion so readers understand why certain studies were excluded.
Item 6: Information Sources. Specify all databases, registers, websites, organisations, reference lists, and other sources searched or consulted to identify studies. Give the date when each source was last searched. Common sources include PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov.
Item 7: Search Strategy. Present the full search strategies for all databases, registers, and websites, including any filters and limits. This item requires you to show the exact search strings with Boolean operators, field tags, and MeSH terms. Many journals ask for this in an appendix or supplementary file.
Item 8: Selection Process. Specify the methods used to decide whether a study met the inclusion criteria. Report how many reviewers screened titles and abstracts, how many reviewed full texts, and how disagreements were resolved. State whether you used automation tools and whether reviewers were blinded to journal or author names.
Item 9: Data Collection Process. Describe methods to collect data from reports, including how many reviewers extracted data, whether they worked independently, and any processes for obtaining or confirming data from study investigators. Report the data extraction form structure and pilot testing procedures.
Item 10: Data Items. List and define all outcomes for which data were sought. Specify whether all results compatible with each outcome domain were sought and the methods used to decide which results to collect. Include the variables extracted such as participant characteristics, intervention details, comparators, and funding sources.
Item 11: Study Risk of Bias Assessment. Specify the methods used to assess risk of bias in the included studies. Name the tool used (such as Cochrane Risk of Bias 2 for randomized trials or ROBINS-I for non-randomized studies), how many reviewers assessed each study, and how disagreements were resolved.
Item 12: Effect Measures. Specify the effect measure used for each outcome in the synthesis or presentation of results. Common measures include risk ratios, odds ratios, mean differences, and standardized mean differences. State whether you used adjusted or unadjusted estimates.
Item 13: Synthesis Methods. Describe the processes used to decide which studies were eligible for each synthesis. Report methods for preparing data before analysis, methods for tabulating or visually displaying results, and methods for statistical synthesis. State whether you used fixed-effect or random-effects models and how heterogeneity was assessed.
Item 14: Reporting Bias Assessment. Describe methods to assess risk of bias due to missing results in a synthesis, such as publication bias and selective reporting. Common approaches include funnel plots, Egger regression tests, and comparison with trial registrations.
Item 15: Certainty Assessment. Describe methods used to assess certainty or confidence in the body of evidence for an outcome. The GRADE approach is commonly used and rates certainty as high, moderate, low, or very low based on risk of bias, inconsistency, indirectness, imprecision, and publication bias.
Results Items
Item 16: Study Selection. Present the numbers of records identified, records screened, reports sought for retrieval, reports assessed for eligibility, and studies included. Show exclusions at each stage with reasons. The PRISMA flow diagram provides a standard visual format for this information.
Item 17: Study Characteristics. Cite each included study and present its characteristics. Report participant demographics, intervention details, comparators, follow-up durations, settings, and funding sources. A characteristics table helps readers compare studies at a glance.
Item 18: Risk of Bias in Studies. Present assessments of risk of bias for each included study. Use tables or figures that show the domain-level judgments and overall ratings. This transparency lets readers judge how much confidence to place in the results.
Item 19: Results of Individual Studies. For all outcomes, present the effect estimates and confidence intervals for each included study. Include the number of participants and events for binary outcomes and means with standard deviations for continuous outcomes. Forest plots display this information effectively.
Item 20: Results of Syntheses. Present results of all statistical syntheses conducted. For each synthesis, report the summary estimate, confidence interval, and measures of heterogeneity. If some studies could not be included in a synthesis, describe their results narratively.
Item 21: Reporting Biases. Present assessments of risk of bias due to missing results for each synthesis assessed. Show funnel plots when appropriate and report statistical tests for asymmetry.
Item 22: Certainty of Evidence. Present assessments of certainty or confidence in the body of evidence for each outcome assessed. Use GRADE summary of findings tables to display certainty ratings alongside effect estimates.
Discussion Items
Item 23: Discussion. Provide a general interpretation of the results in the context of other evidence. Discuss limitations of the included studies and of the review process. Explain the implications for practice, policy, and future research. Avoid overstating conclusions beyond what the evidence supports.
Other Information Items
Item 24: Registration and Protocol. Provide registration information for the review, including register name and registration number, or state that the review was not registered. Indicate where the protocol can be accessed and describe any protocol amendments.
Item 25: Support. Describe sources of financial or non-financial support for the review and the role of funders in the review process. This disclosure aligns with the NIH Grants and Funding expectations for transparency in research supported by public funds.
Item 26: Competing Interests. Declare any competing interests of review authors. The Committee on Publication Ethics core practices require disclosure of financial and non-financial relationships that could influence the review.
Item 27: Availability of Data and Other Materials. Report which of the following are publicly available and where they can be found: data extraction forms, data used for analyses, analytic code, and other materials used in the review. The NIH Data Management and Sharing Policy describes expectations for sharing scientific data generated from NIH-funded research.
Practical Workflow for PRISMA Compliance
Step 1: Register Your Protocol
Register your systematic review protocol before starting data extraction. Prospective registration reduces the risk of reporting bias because your planned methods are publicly documented. Common registries include PROSPERO for health-related reviews and the Open Science Framework for other disciplines. Your registration should state your research question, search strategy, eligibility criteria, and planned analyses.
Step 2: Build and Document Your Search Strategy
Develop your search strategy with input from a librarian or information specialist when possible. Document every database, the exact search string, the date searched, and any filters applied. Save your search histories so you can reproduce them later. The National Library of Medicine resources explain how to construct searches using controlled vocabulary and text words.
Step 3: Screen and Select Studies
Screen titles and abstracts against your eligibility criteria, then retrieve full texts for potentially eligible records. Document the number of records at each stage and record reasons for exclusion at the full-text stage. Use a screening tool or spreadsheet to track decisions. Have at least two reviewers screen independently and resolve disagreements through discussion or a third reviewer.
Step 4: Extract Data and Assess Risk of Bias
Develop a data extraction form that captures all items you plan to report. Pilot the form on several studies and refine it before full extraction. Assess risk of bias using validated tools appropriate for your study designs. Record domain-level judgments and support for each judgment.
Step 5: Conduct and Document Syntheses
For statistical syntheses, document your effect measures, models, heterogeneity assessments, and sensitivity analyses. For narrative syntheses, describe how you grouped studies and what patterns you observed. Keep records of all analyses so you can report them accurately.
Step 6: Complete the Checklist Before Submission
Work through all 27 items and verify that your manuscript addresses each one. Use the PRISMA 2020 checklist as a submission cover sheet where the journal requires it. The EQUATOR Network provides access to the checklist and explains how journals use reporting guidelines in peer review.
Records and Measurements You Should Keep
| Record Type | What to Document | Why It Matters |
|---|---|---|
| Search Log | Database name, platform, date, search string, results count | Reproducibility and PRISMA Item 7 compliance |
| Screening Log | Records screened, excluded, and reasons at each stage | PRISMA Item 16 flow diagram accuracy |
| Data Extraction Forms | All variables extracted from each study | Transparency and verification of Item 9 and 10 |
| Risk of Bias Tables | Domain judgments and supporting text for each study | Item 11 and 18 compliance |
| Analysis Scripts | Code for statistical analyses and figures | Reproducibility and Item 27 data availability |
| Protocol Amendments | Changes to registered protocol with dates and reasons | Item 24 transparency |
Common Failure Patterns in PRISMA Reporting
Incomplete Search Strategy Reporting
Many manuscripts state that a search was conducted in PubMed and Embase without providing the actual search strings. This failure prevents replication and triggers revision requests. Always include the full search strategy for at least one major database in the main text or supplementary materials.
Missing Flow Diagram Numbers
The PRISMA flow diagram requires specific numbers: records identified, duplicates removed, records screened, reports sought, reports assessed, studies included, and studies excluded with reasons. Authors often report only the final included number, leaving reviewers unable to assess the screening process.
Vague Risk of Bias Descriptions
Saying "risk of bias was assessed" without naming the tool, the number of reviewers, or the resolution process fails Item 11. Name the specific tool and describe your assessment procedures in enough detail for replication.
Ignoring Certainty of Evidence
Many reviews report effect estimates without assessing certainty. PRISMA 2020 requires certainty assessment for each outcome. If you do not use GRADE, state what alternative approach you used and justify it.
Omitting Registration Information
Reviews that omit registration details raise concerns about selective reporting. State clearly whether the review was registered, where, and with what number. If not registered, say so explicitly instead of leaving the matter ambiguous.
Undisclosed Conflicts of Interest
The Committee on Publication Ethics core practices require transparent conflict disclosure. Review authors with financial ties to product manufacturers must declare these relationships. Failure to disclose creates ethical problems regardless of whether the conflict influenced the review.
Welfare and Safety Context for Life Science Reviews
Systematic reviews in life sciences often address questions about animal welfare, laboratory practices, and veterinary interventions. When your review includes animal studies, report ethical approval details for the primary studies and consider whether the review itself raises ethical questions about data sharing or animal use.
The NIH Grants and Funding policies require rigorous experimental design and transparent reporting for funded research. If your systematic review is supported by NIH funds, your reporting must meet these expectations. The NIH Data Management and Sharing Policy requires you to plan for data sharing and describe your approach in grant applications.
For reviews involving animal studies, follow established reporting standards for animal research in addition to PRISMA. These standards help readers assess the translational relevance of animal findings and reduce waste in animal research. Your review should report species, strain, sex, age, housing conditions, and welfare assessments when these details are available in the primary studies.
Limitations of the PRISMA 2020 Checklist
PRISMA 2020 does not tell you how to conduct a systematic review. It only specifies what to report. A review can be PRISMA-compliant yet methodologically flawed if the underlying conduct was poor. Conversely, a well-conducted review can fail PRISMA if the authors omit reporting details.
The checklist does not prescribe specific methods for risk of bias assessment, synthesis, or certainty assessment. You must choose appropriate methods for your review question and study designs. PRISMA requires that you report your choices, not that you use any particular tool.
PRISMA 2020 was designed primarily for health research. Life science reviews that include ecological studies, in vitro experiments, or qualitative research may need additional reporting guidance. The EQUATOR Network maintains guidelines for many study types, and you should check whether a more specific guideline applies to your review.
The checklist does not address every possible reporting element. You may need to report additional items required by your journal, funder, or discipline. Treat PRISMA as a minimum standard instead of a complete specification.
Professional Escalation Criteria
Seek guidance from a librarian or information specialist when developing your search strategy, especially for complex questions involving multiple databases and search concepts. A specialist can help you build sensitive searches that balance recall and precision.
Consult a statistician when planning your synthesis methods, particularly for meta-analysis. Statistical decisions about effect measures, models, and heterogeneity assessment affect the validity of your conclusions. A statistician can help you choose appropriate methods and interpret results correctly.
Involve a second reviewer with content expertise in your screening and risk of bias assessment. Independent duplicate assessment reduces errors and improves reliability. If you work alone, consider whether your review can meet the expectations for independent assessment that many journals require.
Contact the journal editor before submission if you are uncertain whether PRISMA 2020 applies to your review type. Some journals have specific requirements for reporting guidelines and may ask you to complete a checklist as part of submission. The EQUATOR Network provides guidance for authors on using reporting guidelines.
Frequently Asked Questions
What is the difference between PRISMA 2020 and the older PRISMA 2009 checklist?
PRISMA 2020 updated the 2009 version to reflect advances in systematic review methods. The new version added items for searching databases and registers separately, reporting synthesis methods in more detail, and assessing certainty of evidence. It also restructured the flow diagram and clarified reporting expectations for each item.
Do I need to complete the PRISMA 2020 checklist for a narrative literature review?
No. PRISMA 2020 applies to systematic reviews and meta-analyses. Narrative literature reviews do not follow the same systematic methods and should not use the PRISMA checklist. The EQUATOR Network provides guidance for selecting the appropriate reporting guideline for your study type.
Can I use PRISMA 2020 for a systematic review of animal studies?
Yes, PRISMA 2020 can be used for systematic reviews of animal studies. However, you may need additional reporting elements specific to animal research, such as species, strain, sex, and housing conditions. Check whether your target journal requires additional reporting standards for animal studies.
Where can I find the official PRISMA 2020 checklist and flow diagram?
The EQUATOR Network provides access to the PRISMA 2020 statement, checklist, and flow diagram. The PRISMA website also hosts these materials. Many journals include the checklist in their author instructions or submission systems.
What should I do if my review was not registered?
State clearly in your manuscript that the review was not registered. Explain any reasons for the lack of registration if appropriate. Some journals and funders prefer prospective registration, but retrospective reporting of an unregistered review is still possible if you are transparent about it.
How do I report a search strategy that was updated during the review?
Describe the original search strategy and any updates with dates. Report the final search strategy used for each database and note when updates occurred. This transparency allows readers to understand the complete search process and assess whether relevant studies might have been missed.
Does PRISMA 2020 require me to share my data and analysis code?
Item 27 asks you to report which materials are publicly available and where they can be found. You must state whether data extraction forms, data used for analyses, and analytic code are available. The NIH Data Management and Sharing Policy describes expectations for NIH-funded research, and many journals now require data availability statements.
What happens if I do not follow PRISMA 2020 in my systematic review manuscript?
Journals increasingly require PRISMA compliance for systematic review submissions. Missing items typically trigger revision requests. Some journals reject manuscripts that do not follow applicable reporting guidelines. The Committee on Publication Ethics core practices support transparent reporting as an ethical obligation in research publication.
Related Articles
- Conducting a Study: A Practical Checklist for Life Science Researchers
- What Is Data Management? A Primer for Life Science Researchers
- Conducting Qualitative Interviews: A Guide for Life Science Researchers
- The Role of the Research Ethics Committee: What Researchers Need to Know
- Observational vs. Experimental Studies: A Decision Framework for Life Science Researchers
References and Further Reading
- Research Methods Resources. National Library of Medicine.
- EQUATOR Network. EQUATOR Network.
- Core Practices. Committee on Publication Ethics.
- NIH Grants and Funding. National Institutes of Health.
- ORCID for Researchers. ORCID.
- Data Management and Sharing Policy. National Institutes of Health.
- NCBI Literature Resources. National Center for Biotechnology Information.
- PubMed. National Library of Medicine.
This article is educational and does not replace institutional policy, professional advice, or applicable safety and regulatory requirements.