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Intention-to-treat analysis — USMLE Step 3 MCQ

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HardPreventive Medicine, Epidemiology, BiostatisticsIntention-to-treat analysisUSMLE Step 3

A randomized smoking-cessation trial analyzes participants in the groups to which they were allocated even when some did not use the assigned intervention. What is the main reason for this intention-to-treat analysis?

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Correct answer: D — It preserves the comparability created by random treatment allocation

Intention-to-treat analysis retains the groups created by randomization and limits bias from post-randomization adherence differences. It does not ensure adherence, erase missing data, or restrict analysis to adherent participants.

Reference: CDC, Principles of Epidemiology in Public Health Practice: https://www.cdc.gov/csels/dsepd/ss1978/lesson3/section6.html