Lancet Reporting

Reporting Guidelines & Flow Diagrams (lancet-reporting)

When to trigger

• The study type is settled and you need the matching reporting checklist.
• There is no participant flow diagram (CONSORT/PRISMA) in the manuscript.
• A reviewer or editor asks for a completed reporting checklist with page/line references.
• The manuscript mixes endpoints/numbers that the flow diagram should reconcile.

Pick the guideline by study type (via EQUATOR)

The Lancet requires the appropriate EQUATOR Network reporting guideline and a completed checklist on submission.

The flow diagram is mandatory for RCTs and systematic reviews

• CONSORT flow diagram present for every RCT: numbers assessed for eligibility, excluded (with reasons), randomized, allocated, lost to follow-up/discontinued (with reasons), and analyzed in each arm.
• PRISMA flow diagram present for every systematic review/meta-analysis: records identified, duplicates removed, screened, full-text assessed, excluded (with reasons), and included.
• Every number in the flow diagram reconciles with Table 1, the analysis populations, and the abstract.

Checklist discipline

• Complete the official checklist for the chosen guideline.
• Map each item to a page and line in the manuscript (editors and reviewers check this).
• Use the correct extension (e.g., CONSORT cluster for cluster-randomized trials; CONSORT harms for adverse-event reporting; CONSORT-PRO for patient-reported outcomes).
• Submit the checklist as a supplementary file.

Equity-relevant reporting

• Apply equity-focused extensions where relevant (e.g., PRISMA-Equity, CONSORT-Equity considerations) and the PROGRESS-Plus framework for reporting equity-relevant participant characteristics.
• Coordinate sex/gender and race/ethnicity reporting with lancet-ethics (SAGER guidelines).

What Lancet editors and reviewers expect from reporting compliance

A completed checklist is a screening gate at The Lancet, not a formality. Editors and the statistical reviewer cross-read the flow diagram against Table 1 and the analysis populations; a discrepancy reads as a transcription error or selective reporting, and unexplained attrition is where bias hides. Desk-reject-adjacent patterns: no flow diagram for an RCT or review (effectively mandatory); base CONSORT where a cluster/non-inferiority extension fits; a checklist that says "throughout" instead of page/line; and numbers that do not reconcile. Confirm any current formatting requirement against the journal's author guidelines.

Worked micro-example (illustrative numbers — not real data)

A hypothetical multi-country, individually randomised trial of an oral therapy versus placebo across 14 sites in 5 low- and middle-income countries.

Guideline: CONSORT 2010 + CONSORT-Harms; checklist page/line-mapped as a supplement.
CONSORT flow diagram (illustrative):
  Assessed 5 312 -> Excluded 1 108 (ineligible 842; declined 201; other 65)
  Randomised 4 204 -> intervention 2 102 / placebo 2 102
  Lost to follow-up: intervention 51, placebo 58 (reasons listed)
  Analysed (ITT): 2 102 / 2 102
Reconciliation: 4 204 = Table 1 total = abstract Findings denominator. PASS.

The reporting pass is the reconciliation: 4 204 appears identically in the diagram, Table 1, and the abstract, and every exclusion and dropout carries a reason.

Reviewer-pushback patterns and the venue-specific fix

• "The reporting checklist is incomplete / not page-referenced." → Complete the official EQUATOR checklist and map each item to a page and line; resubmit as a supplement.
• "This is a cluster-randomised trial but reported under standard CONSORT." → Switch to CONSORT-Cluster with cluster-level flow and intracluster correlation reporting.
• "Flow-diagram numbers do not match the analysis populations." → Rebuild the diagram so randomised, analysed, and Table 1 totals reconcile; explain any gap.
• "Equity-relevant characteristics are not reported." → Add PROGRESS-Plus variables and a PRISMA-Equity/CONSORT-Equity lens; coordinate with lancet-ethics.

Output format

【Study type】 RCT / observational / systematic review / protocol / other
【Guideline + extension】 CONSORT(+ext) / STROBE / PRISMA(+ext) / SPIRIT / STARD / TRIPOD / ...
【Flow diagram】 present & required? CONSORT / PRISMA / N/A  → gaps
【Flow numbers reconcile】 with Table 1 + analysis populations + abstract? yes/no
【Checklist】 completed + page/line mapped? yes/no
【Equity reporting】 PROGRESS-Plus / equity extension applied where relevant? yes/no
【Next】 lancet-statistics

Anti-patterns

• Do not submit an RCT without a CONSORT flow diagram, or a systematic review without a PRISMA one.
• Do not leave flow-diagram numbers that disagree with the analysis populations or Table 1.
• Do not submit a checklist with "see manuscript" instead of specific page/line references.
• Do not use the base guideline when an extension fits the design better (cluster, non-inferiority, pragmatic, harms).