Calculating risk reduction and number needed to treat

Although most scientific works usually analyze their data in terms of statistical significance, it is less frequent to find information about its clinical relevance. Calculating relative risks, relative risk reduction, absolute risk reduction and number needed to treat may help us to determine the clinical significance of the study results. Absolute risk reduction (risk difference between intervention and control branches) and its inverse value, number needed to treat, are the most useful figures to quantify the effort that will have to be made to achieve one more event of the desired effect.