Biology Systematic Literature Review

Proof required

Submit your PROSPERO registration number (or equivalent pre-registration) showing the question, inclusion/exclusion criteria, and search strategy. Submit your documented database search results showing the search string used, the databases searched (at minimum PubMed and one other), and the initial hit counts per database.

What gets checked

• PROSPERO registration was submitted before the search was conducted — retroactive registration changes the meaning of pre-registration
• Search string uses Boolean operators correctly and includes synonyms for key concepts — not a single-term search
• Inclusion and exclusion criteria are explicit and testable — not vague ('high-quality studies') but specific ('randomised controlled trials published 2010–2024 in adult humans')

Common mistakes

• Beginning the search before registering the protocol — pre-registration only prevents outcome-reporting bias if the protocol is committed to before results are seen
• Searching only one database — PubMed alone misses substantial relevant literature; Embase, Web of Science, or Cochrane CENTRAL should also be searched

Resources

What a verifier looks for

• Ask the submitter to confirm their PROSPERO registration number — it should be findable on the PROSPERO website.
• Ask why they chose their specific inclusion/exclusion criteria — particularly any non-obvious cutoffs (year range, study type, population) should have explicit justifications.
• Ask how many results they retrieved before deduplication and from which databases — confirms the search was actually run as documented.

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Proof required

Submit your PRISMA flow diagram showing record counts at each stage (identified, screened, assessed, included), your full-text exclusion log with reasons, and your completed data extraction table for included studies.

What gets checked

• PRISMA flow diagram matches the numbers in the search documentation from M1 — any discrepancies between M1 hit counts and M2 screened counts should be explained
• Full-text exclusion log states a specific reason for each excluded paper (e.g., 'wrong outcome measured', 'not a controlled study') — not just 'excluded'
• Data extraction table captures all pre-specified outcomes from the M1 protocol — not just the outcomes that turned out to be significant

Common mistakes

• Changing inclusion criteria after seeing the full-text results to include studies that seem interesting — this is outcome-reporting bias and invalidates the systematic review
• Not recording exclusion reasons at the full-text stage — PRISMA requires specific reasons; undocumented exclusions cannot be reviewed

Resources

What a verifier looks for

• Ask the submitter to explain one borderline full-text exclusion decision — why a specific paper was excluded despite seeming relevant.
• Check that the PRISMA flow diagram numbers are internally consistent — records screened must equal records identified minus duplicates removed.
• Ask whether a second screener reviewed any portion of the full-text screening stage — inter-rater reliability, even informal, strengthens credibility.

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Proof required

Submit your complete systematic review document following PRISMA 2020 reporting (introduction, methods, results with PRISMA flow diagram, discussion, conclusions, GRADE summary table or equivalent evidence quality assessment) and a written Q&A record showing the reviewer's specific challenges and your responses. PROSPERO registration number must appear in the document.

What gets checked

• PRISMA checklist is completed and submitted alongside the review — all items are addressed or explicitly noted as not applicable
• Evidence quality is assessed using GRADE or a stated equivalent — not just 'evidence is weak or strong' without a framework
• Q&A record shows at least two methodological challenges from the reviewer (not just clarification questions) and substantive responses

Common mistakes

• Conclusions that go beyond what the included studies demonstrate — systematic reviews are bounded by their inclusion criteria; extrapolation beyond included populations or study types must be explicitly flagged
• A reviewer who is not familiar with systematic review methodology — the Q&A must include challenges about inclusion decisions, search completeness, or evidence quality assessment, which requires reviewer familiarity with the method

Resources

What a verifier looks for

• Ask the submitter what their overall GRADE rating for the body of evidence was and what drove it — they should be able to name the specific factors (risk of bias, inconsistency, indirectness, imprecision).
• Ask whether their search might have missed important literature and what databases or grey literature sources they did not search — an honest answer indicates genuine understanding of search limitations.
• Verify the reviewer has systematic review experience or public health research experience — a general biologist without experience in systematic reviews may not be able to generate appropriate methodology challenges.

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