[NNT--numbers needed to treat].

Number needed to treat--NNT--is a bridging tool between statistical results from clinical trials and the physician daily work. This number represents the number of patients we need to treat with the experimental therapy in order to prevent one of them from developing the bad outcome. The concept is a useful measure of the clinical effort our patient and we must expend in order to help them avoid bad outcomes to their illness. For example, the NNT for antibiotic treatment of otitis media is 8, which means that we have to treat eight children with antibiotic and only one out of the eight will benefit the treatment. In a medical world that uses the Evidence Based Medicine as essential tool, we believe that the NNT is an important tool and very efficient for choosing the best treatment method.