Which of the following is the primary advantage of using intention-to-treat (ITT) analysis in randomized controlled trials?

## Intention-to-Treat (ITT) Analysis **Key Point:** ITT analysis includes all randomized participants in their assigned group regardless of adherence, dropout, or protocol violations. It preserves the benefits of randomization and reduces bias. ### Definition Intention-to-treat analysis analyzes participants in the groups to which they were randomly assigned, regardless of whether they: - Received the assigned treatment - Adhered to the treatment protocol - Completed the trial - Switched treatments ### Primary Advantage: Preservation of Randomization | Aspect | ITT Analysis | Per-Protocol Analysis | |--------|--------------|----------------------| | **Includes** | All randomized participants | Only those who adhered to protocol | | **Bias risk** | Lower (preserves randomization) | Higher (selection bias from exclusions) | | **Generalizability** | Better (reflects real-world adherence) | Worse (excludes non-compliant patients) | | **Statistical power** | May be reduced (dilution effect) | Appears higher but biased | **High-Yield:** ITT analysis is the gold standard for efficacy and safety assessment in RCTs because it: 1. Maintains the balance of known and unknown confounders achieved by randomization 2. Reflects the true effectiveness of treatment in real-world conditions (including non-adherence) 3. Prevents selection bias from differential dropout or protocol violations ### Why ITT Reduces Bias When participants are excluded post-randomization (per-protocol analysis), the groups may no longer be comparable. For example: - Sicker patients may drop out more frequently from the active treatment group - Excluding them creates a spuriously favorable treatment effect - ITT avoids this by keeping all randomized participants in their original groups **Clinical Pearl:** The difference between ITT and per-protocol results can reveal important information about treatment tolerability and real-world effectiveness. **Mnemonic:** **ITT = Integrity Through Treatment** — maintain the integrity of randomization by analyzing all participants as assigned.