Baseline characteristics

Initial collection of demographics which serves as a basis for comparison with the subsequently acquired data.

The demographic, clinical and other objective data collected for each participant at the beginning of a clinical trial before intervention.

Initial collection which serves as a basis for comparison with the subsequently acquired data.

Randomised controlled trials aim to compare groups of participants that differ only with respect to the intervention (treatment); while proper random assignment prevents selection bias, it does not guarantee that the groups are equivalent at baseline—e.g., any differences in baseline characteristics are the result of chance rather than bias. The study groups should be compared at baseline for important demographic and clinical characteristics.