The NNT (number needed to treat) is an absolute measure used to assess the magnitude of effect of a technology. NNT can be defined as the number of patients who need to be treated with one technology versus another for 1 additional patient to have the expected outcome. When the technology results in clinical benefits, we call it “number needed to treat”, while therapies that can increase the rate of adverse events, for example, we call it “number needed to harm”.

The importance of NNT also lies in its ease of understanding, making the communication of clinical trial results to physicians, managers and patients more effective. Compared to other measures such as p-value, risk ratios and odds ratios, the impact and clinical significance are clearly established with the NNT.