Biostatistics & Study Design USMLE Step 1 Practice Question
A 45-year-old woman with chronic migraines (BP 128/82, HR 82, previously on topiramate) enrolls in a crossover trial comparing two prophylactic medications. After completing the first 8-week treatment phase with Drug A, she discontinues all study medication for 3 weeks before beginning Drug B. Headache frequency remains stable during the washout period. Which of the following is the primary reason for this mandatory interval between treatment phases?
Answer choices
- AImprove specificity of the primary endpoint
- BPrevent carryover effects from the first treatmentCorrect answer
- CDecrease type I error
- DIncrease allocation concealment
- EReduce attrition bias
- FAllow sufficient time for pharmacokinetic equilibrium of endogenous neurotransmitters
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