Assessing the benefit: risk ratio of a drug--randomized and naturalistic evidence.

Randomized evidence from clinical trials and naturalistic evidence collected from pharmacoepidemiology and pharmacovigilance activities both contribute to the initial and continuous assessment of the benefits and risks of a drug, ie, the balance between therapeutic efficacy and safety risks. Benefit-risk assessment (BRA) mainly relies on a qualitative assessment of quantitative data. Current attempts to quantify BRA are reviewed and discussed, along with the expectations of regulatory authorities such as the Food and Drug Administration and the European Medicines Agency. No method provides a fully satisfactory solution regarding BRA, because it is difficult to reduce its multidimensional aspect to simple metrics, in a context where other therapeutic alternatives play a role. Consistency and transparency are key in this assessment, which is performed throughout the whole drug life cycle. BRA is mainly based on randomized clinical studies during clinical development, and it is continued and consolidated by naturalistic data once the drug is on the market.