ClinicalTrials.gov Definitions

This page defines the data fields that are submitted to ClinicalTrials.gov for interventional studies (clinical trials) and observational studies. These definitions are mostly adapted from 42 CFR Part 11.

Interventional

Observational

Arms (Interventional)

Groups/Cohorts (Observational)

Intervention(s)

*Any interventions that are added should be correctly cross-matched to the corresponding intervention arm(s).

Primary Outcome Measure is referring to the outcome measure(s) of greatest importance (as specified in the protocol), which usually include the one(s) used in power calculation. Clinical studies should have at least one primary outcome measure, but some many have several.

Secondary Outcome Measure is referring to the outcome measure(s) that are of lesser importance than the primary outcome measure(s), but is part of a pre-specified statistical analysis plan for evaluating the effects of the intervention(s). A clinical study can have more than one secondary outcome measure.

Other Pre-specified Outcome Measure is referring to any other measurements that will be used to evaluate the intervention(s) or for observational studies, that are a focus of the study.

Outcome Measure(s)

Interventional Trials

Observational Studies