Consider a study evaluating a new drug for hypertension. If the event rate for a serious side effect in the treatment group is 5% and in the control group is 1%, the ARI would be 0.04 (or 4%). The NNH would be calculated as:
NNH = 1 / 0.04 = 25
This means that 25 patients would need to be treated for one to experience a serious side effect.
