Intent-to-treat analysis includes all randomized participants in the analysis, regardless of adherence.

• A. True
• B. False
• C. True only if adherence is high
• D. True only in nonrandomized studies

Answer: (A)

Intention-to-treat analysis includes all participants who were randomized and analyzes them in the groups to which they were assigned, regardless of whether they adhered to the assigned treatment, completed the study, or switched treatments. This approach preserves the benefits of randomization, maintaining group comparability and avoiding bias that can occur when nonadherent or withdrawn participants are excluded or reclassified. It also reflects real-world effectiveness, where adherence varies. In contrast, per-protocol or as-treated analyses exclude nonadherents or reclassify participants by what they actually received, which can bias results because the groups may no longer be comparable. Therefore, including all randomized participants regardless of adherence is the correct approach.