In a randomized trial of a new antidiabetic drug versus placebo, 15% of patients assigned to the drug stop taking it after 6 months. At trial end, the analysis includes every patient in their original assigned group regardless of adherence. This analytic approach primarily protects against:
- A Loss of benefit of randomization due to selective attrition between arms ✓
- B Type II error from insufficient sample size
- C Confounding by indication
- D Ascertainment bias in outcome assessment
Correct answer: A. Loss of benefit of randomization due to selective attrition between arms
Explanation
Intention-to-treat analysis analyzes participants in the groups to which they were randomized, irrespective of adherence. Noncompliers usually differ prognostically from compliers, so excluding them or reassigning them would break the balance created by randomization and reintroduce selection bias between arms. Confounding by indication threatens observational studies where treatment is given based on severity, not randomized trials. Blinded outcome assessment addresses ascertainment bias, and sample size calculations address type II error separately.
Reference: Gordis Epidemiology, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.