A randomized double-blind placebo-controlled trial to assess the efficacy of drug X in the treatment of Crohn’s disease. 100 people were recruited into the study and were divided equally between the treatment arm and the control group. Over the course of one year, 90 of the 100 people who were treated with drug did not incur side effects, whereas 95 of 100 people in the placebo group did not incur side effects. How many people treated with drug X for one year will suffer from side effects that they would not have otherwise experienced?
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- 5
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- 10
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- 20
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- 25
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- 50
0 voters
EXP:
This questions asks you to calculate the Number Needed to Harm (NNH). The NNH is the reciprocal of the Absolute Risk Increase (ARI). That is, NNH = 1/ARI. ARI = absolute value of the difference between incidence in the exposed and incidence in the enexposed. In the case presented, incidence of side effects was the outcome of interest. In the exposed, this incidence was 10 of every 100 people treated with drug X, and 5 out of every 100 people treated with placebo. That means that the incidence of effects solely attributable to drug X in this case is .05, explained by the equation ARI = incidence exposed - incidence unexposed = 0.1-0.05 = 0.05. Thus, NNH = 1/ARI = 1 /0.05 = 20.