Biostatistics & Study Design USMLE Step 1 Practice Question
A randomized controlled trial evaluating a new antihypertensive medication requires all participants to complete a 2-week placebo run-in phase before randomization. Patients presenting with baseline BP 168/104 mmHg, HR 92/min, and no prior antihypertensive use are enrolled. Those who miss >20% of placebo doses or withdraw during run-in are excluded before assignment to treatment arms. Serum creatinine remains normal throughout. Which of the following best describes the primary purpose of this run-in design feature?
Answer choices
- AEliminate confounding by age
- BPrevent lead time bias
- CMeasure incidence density
- DIncrease blinding of outcome assessors
- EIdentify likely nonadherent participants before randomizationCorrect answer
- FReduce regression to the mean
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