The Number Needed to Treat (NNT) is another important measure in epidemiology that is directly derived from ARR. NNT indicates how many patients need to be treated to prevent one additional adverse event. NNT is calculated as the inverse of ARR: NNT = 1 / ARR Using the previous example, if the ARR is 10%, the NNT would be: NNT = 1 / 0.1 = 10 This means that 10 patients need to be treated to prevent one additional adverse event.
