Epidemiology & Prevention USMLE Step 1 Practice Question
A 45-year-old woman with stage 2 hypertension is enrolled in a randomized controlled trial comparing a new ACE inhibitor (lisinopril-amlodipine combination) to standard monotherapy (lisinopril alone). At baseline, both groups have mean systolic blood pressure of 155 mmHg. After 12 weeks of treatment, the combination therapy group achieves a mean SBP of 135 mmHg (95% CI 130-140 mmHg), while the monotherapy group achieves a mean SBP of 138 mmHg (95% CI 133-143 mmHg). The p-value for the between-group difference is 0.08. Which of the following is the most appropriate interpretation of these findings?
Answer choices
- AThe combination therapy is significantly superior because it achieved a 3 mmHg greater reduction in blood pressure
- BThe results demonstrate a Type I error, as the p-value exceeds the conventional significance threshold
- CThe finding is statistically non-significant; the overlapping confidence intervals and p-value > 0.05 indicate insufficient evidence to reject the null hypothesisCorrect answer
- DThe study proves the null hypothesis is true and both treatments are equally effective
- EThe result is statistically significant because the confidence intervals do not completely overlap at zero
- FA Type II error has occurred, meaning the new combination therapy is definitively ineffective
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