Number Needed to Treat: an Important Measure for the Correct Assessment of Clinical Significance

Number Needed to Treat (NNT) is a concept first found in papers published by Laupacis et al. in the New England Journal of Medicine in 1988. NNT is the average number of patients who need to be treated to prevent one additional bad outcome (e.g. the number of patients that need to be treated for one to benefit compared with a control in a clinical trial) 1 . This measure assessing the clinical significance of any kind of intervention has since been applied with increasing frequency. This concept is frequently used in psychiatry, especially when comparing the efficacy and effectiveness of drugs and is seen as an important indicator to demonstrate the advantage of a new drug over a standard or reference drug and/or placebo treatment 2-5 .