What Is PRISMA 2020? An Academic and Practical Guide to Systematic Reviews

1. The central problem PRISMA addresses

Imagine two teams reviewing the same question, such as the relationship between transformational leadership and employee engagement. Both call their work a systematic review. One specifies the databases, complete search strings, full-text exclusions and reasons. The other merely says it searched several databases and selected relevant studies. When their conclusions differ, which should readers trust?

In international publication, the answer should rest on process transparency rather than authors' personal reputations. Readers must be able to examine the path from the research question to the final evidence base. Without adequate reporting, the conclusions might still be correct, but readers lack the information needed to judge them.

PRISMA responds to this need. The acronym stands for Preferred Reporting Items for Systematic reviews and Meta-Analyses. It is a reporting guideline that helps authors explain why a review was conducted, which methods were used and what was found. PRISMA 2020 updates the 2009 version to reflect developments in evidence synthesis, including more detailed reporting of search strategies, screening, risk of bias, data availability and flow diagrams.

2. What is PRISMA 2020?

PRISMA 2020 is a reporting guideline for systematic reviews and meta-analyses. Its main question is what authors must report for readers to understand and assess the review process. It does not replace methodological resources such as the Cochrane Handbook, JBI Manual for Evidence Synthesis or specialist meta-analysis textbooks.

Distinguishing reporting guidance from conduct guidance matters. Using the checklist during planning does not make PRISMA the entire methodology. For example, it requires reporting how risk of bias was assessed but does not choose the instrument. The suitability of RoB 2, ROBINS-I, the Newcastle-Ottawa Scale, MMAT or another instrument depends on the included study designs.

PRISMA 2020 includes a 27-item checklist, an expanded checklist, an abstract checklist, flow diagrams and an Explanation and Elaboration paper with examples. Beginners often need more than the checklist alone. The explanation paper clarifies why each item matters and what adequate reporting looks like.

3. How does PRISMA 2020 differ from PRISMA 2009?

The update goes beyond presentation. It retains the 27-item structure while revising wording, expanding requirements and clarifying recurrent misunderstandings. Its overall emphasis is greater transparency, particularly where bias may arise without being readily apparent.

Using PRISMA 2009 for a new review is generally no longer a good choice for international journals. Reviewers may request an updated checklist and flow diagram when a manuscript is submitted after PRISMA 2020 has become established.

4. The logic of the 27 reporting items

The checklist may initially seem long, but the 27 items follow the familiar structure of a scientific article: title, abstract, introduction, methods, results, discussion and additional information.

4.1. Why are Methods central to PRISMA?

Methods account for the largest share because they establish the review's systematic nature. A review is not systematic simply because it has many references. Its search, selection, appraisal and synthesis procedures must be specified in advance, applied consistently and reported transparently.

Four areas often determine how convincing the methods are: eligibility criteria; the search strategy, including databases, dates, queries and grey literature; screening and extraction procedures, particularly reviewer numbers and disagreement resolution; and risk-of-bias assessment together with synthesis methods.

4.2. The flow diagram is more than an illustration

The PRISMA flow diagram tracks numbers through identification, screening, full-text eligibility assessment and inclusion. It is often mishandled: some manuscripts include a diagram merely as a formality, with counts that do not match the methods or appendices.

The diagram should show how many records were initially identified, how many duplicates were removed, how many records were excluded after title and abstract screening, how many full texts were assessed and excluded for which reasons, and how many studies were finally included in qualitative synthesis and, where relevant, meta-analysis.

5. Applying PRISMA in social science, economics and management

PRISMA developed strongly within medicine and health research, but its transparency principles have wider value. It can support systematic-review reporting in social science, economics, education and management without mechanically imposing clinical-trial conventions.

5.1. Research questions do not always fit PICO

PICO means Population, Intervention, Comparator and Outcome. It suits intervention-effect questions, such as whether training improves employee competence. Many management and economics questions lack a clinical-style intervention. PECO (Population, Exposure, Comparator, Outcome), SPIDER or other frameworks may fit better.

The aim is not to force every review into PICO, but to clarify the unit of analysis, phenomenon, context and central variables or concepts. A useful question is focused enough for a systematic search while broad enough to contribute to an academic debate.

5.2. Observational designs and contextual heterogeneity are common

Observational studies often make up much of the evidence in management, marketing, education and public policy. Reviews may include cross-sectional surveys, panel data, qualitative studies, case studies, natural experiments and mixed-method designs. Risk-of-bias tools must fit these designs; popularity alone is not a reason to use an instrument that does not fit the question.

High heterogeneity is another challenge. Studies may differ in countries, industries, scales, collection periods and analytical models. A meta-analysis must explain how these differences are handled, for example through random-effects models, subgroup analysis, sensitivity analysis or meta-regression where the data permit.

5.3. Preregistration: PROSPERO, OSF and disciplinary fit

Registering a protocol helps distinguish planned decisions from decisions made after inspecting evidence. PROSPERO is a familiar international systematic-review register, but focuses on reviews with health-related outcomes. For many non-health questions in economics, management, education or social science, OSF Registries can offer a more flexible place for protocols, extraction forms and supporting materials.

Whatever the platform, retain protocol versions, registration dates, amendments and their reasons. These records help address concerns about changing criteria, variables or analyses after learning the findings.

6. A practical workflow for starting a systematic review

Do not start a first systematic review by downloading hundreds of papers and reading at random. Begin with the question and protocol, then progress through searching, screening, extraction, synthesis and reporting.

Use the checklist as a writing tool from day one, rather than a last-minute submission check. Knowing what must be reported helps organize management files, extraction tables and appendices from the start.

7. Common misunderstandings about PRISMA

7.1. PRISMA is not a quality certificate

A flow diagram and completed checklist do not automatically establish quality. Searches can remain narrow, selection criteria biased or synthesis unconvincing despite a fully completed form. PRISMA improves transparency; methodological quality needs assessment using other standards.

7.2. PRISMA is not limited to meta-analysis

PRISMA applies to systematic reviews with or without meta-analysis. When data are insufficiently comparable for pooling, narrative or other forms of synthesis remain possible, provided their procedures are reported transparently.

7.3. Scoping reviews may need a different extension

Scoping reviews have different objectives. Consult PRISMA-ScR for scoping reviews, PRISMA-NMA for network meta-analysis and PRISMA-P for systematic-review protocols. Choosing the appropriate extension helps avoid omitting design-specific reporting items.

7.4. Do not hide limitations to make a manuscript look stronger

A rigorous review need not pretend to be limitation-free. Restrictions involving languages, databases, grey literature, reviewer numbers or heterogeneity can be acceptable when explained honestly. Reviewers are more concerned by ambiguity about what was done, omitted and how those choices may affect conclusions.

8. A quick pre-submission checklist

• The title identifies the work as a systematic review, meta-analysis or both.
• The structured abstract states information sources, eligibility, synthesis methods, principal findings and important limitations.
• The question, objectives and scope are explicit.
• Eligibility criteria were prespecified and are sufficiently concrete to reproduce.
• Full strategies for each database appear in the article or appendices.
• The last search date is stated.
• Deduplication and title, abstract and full-text screening are described transparently.
• Full-text exclusions are listed with reasons.
• Risk-of-bias instruments fit the study designs.
• Synthesis methods explain how heterogeneity was handled, where relevant.
• Flow-diagram counts match the article and appendices.
• The protocol, registration, funding, conflicts of interest and data availability are reported.

9. Key terminology