A randomized controlled trial of a statin analyses all randomized patients in the groups to which they were originally allocated, counting deaths among patients who stopped the drug as drug-group events. The main advantage of this intention-to-treat approach is that it:

• A Preserves the prognostic balance created by randomization ✓
• B Provides the best estimate of efficacy under ideal adherence
• C Eliminates misclassification of the outcome
• D Increases statistical power by excluding protocol violators

Explanation

Intention-to-treat analysis keeps every randomized participant in the original allocation arm, preserving the baseline comparability that randomization achieved. Non-adherence and crossover usually dilute the observed effect, so ITT gives a conservative, real-world estimate of effectiveness. Per-protocol analysis, not ITT, estimates efficacy under ideal adherence. ITT does not affect outcome measurement accuracy and it retains rather than excludes participants, so power relative to a per-protocol subset is maintained or improved.

Reference: Gordis Epidemiology, 6th ed.

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