Compare the registry's enrollment and primary outcome fields with the paper's reported sample and outcomes, then check the record's amendment history before choosing which figure to cite.
ClinicalTrials.gov defines structured registration and results fields for study identification, status, design, eligibility, locations, outcomes, and reported results. That structure gives you specific fields to line up against the paper.
- Pull the registry record and record its registered enrollment figure and primary outcome definition. Use the study identification fields to confirm you have the correct trial, since similar titles and multiple registrations can point to different records.
- Compare those fields with the paper's reported sample size and primary outcomes. Note the exact numbers and outcome wording on each side so the discrepancy is documented rather than remembered.
- Check the record for an amendment or update history and note the date of each change. A registered figure that changed after the paper's publication date describes a different state of the trial than the one the paper reports.
- Decide which figure to cite based on what each source can verify. Cite the registered figure when you are describing the trial as registered, and cite the published figure when you are describing what the paper reports; state the other figure and the discrepancy in a caveat.
If the amendment history does not explain the difference, treat the mismatch as unresolved and report both figures with their sources and dates. For trials registered elsewhere, the WHO ICTRP Search Portal provides a single access point for records supplied by participating registries, so you can locate the relevant record there.