What is the importance of baseline characteristics in a clinical trial?

• The information related to Demographic, clinical, and other data collected for each participant at the beginning of the trial before the intervention is administered is generally considered as 'baseline characteristics'.
• Randomized, controlled trials aim to compare groups of participants that differ only with respect to the intervention (treatment).
• Although proper random assignment prevents selection bias, it does not guarantee that the groups are equivalent at baseline.
• Any differences in baseline characteristics are, however, the result of chance rather than bias.
• The study groups should be compared at baseline for important demographic and clinical characteristics.
• Baseline data may be especially valuable when the outcome measure can also be measured at the start of the trial.

source: CDISC glossary