Using the same trial, in which 20 percent of the controls and 15 percent of the treated patients have a stroke, what is the relative risk reduction?
Answer and explanation
Correct answer: D. 25 percent
- Step 1: Relative risk reduction is the absolute risk reduction divided by the control event rate. Step 2. ARR is 5 percentage points, divided by 20 percent gives 0.25, or 25 percent. The relative risk is 0.75. Answer: 25 percent. Why not the others: 5 percent is the absolute risk reduction. 75 percent is the relative risk, not the reduction. 33 percent would result from dividing by the treated rate of 15 percent.
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