Evidence-based medicine at your fingertips part 3: Therapy

In this third and final article, we describe the step-by-step design and use of a spreadsheet to analyze the results of a therapeutic trial in the literature. The skills required are minimal. The hardware and software requirements are modest, widely available, and relatively cheap. Automatically computed results are: the absolute and relative risk reduction, the 95% confidence intervals for risk reduction, the number needed to treat to cure one patient, and the number of cases needed to be exposed to side-effects to cure one patient. In addition to the elimination of the potential risk of calculation errors, time and effort are saved by the physician. The use of such a spreadsheet will further consolidate the concept of evidence-based medicine (EBM) by readers of the medical literature and will help improve further the quality of care.