NNT is an absolute measure of effect that is used to estimate the efficacy or safety of an intervention. It was originally designed to describe the effect of the intervention relative to the control group in clinical trials, but later its use was extended to interpret the results of systematic reviews and meta-analyzes. It is in these cases that the variability of the risks of the primary studies must be taken into account to obtain a better estimate of their value.El NNT es una medida absoluta de efecto que se utiliza para estimar la eficacia o seguridad de una intervención. En un principio se ideó para describir el efecto de la intervención respecto al grupo control en los ensayos clínicos, aunque posteriormente se extendió su uso para in...