Cohort overview — Retrospective descriptive cohort

Question

State the descriptive population, outcomes and historical period; avoid an unexplained causal claim.

Protocol and data access

Write the protocol, document data permissions and ethics, and specify where a dated protocol or registration will be available.

Assess sources

Assess whether sources capture cohort eligibility, events, deaths and observation time reliably.

Define cohort and time zero

Apply eligibility using information available at entry; define look-back and time zero without requiring later survival.

Derive variables

Specify code lists, measurement windows, validation and missingness for each variable.

Describe outcomes

Estimate distributions, risks or rates with the correct denominators and follow-up methods.

Examine limitations

Assess selection, incomplete capture, coding changes, censoring and sensitivity to definitions.

Report

Report the population, observation period, estimates and uncertainty, with clear limits on interpretation.

Cohort overview

End flow

Protocol and decision register

Record the protocol, approvals and registration where applicable. Preserve planned decisions and amendments separately from results.

Protocol and rationale evidence

Attach the rationale and dated protocol, retaining amendments. A study registry records study details; a disease registry contains health data. The HMA–EMA Catalogue of RWD studies is one option for relevant studies. Check eligibility and applicable requirements, and record an identifier and timing if registered. Registration does not imply randomization.