During the post-registration period, pharmacovigilance through spontaneous reports is critical to consolidate the safety profile of the drug. However, the rarity of spontaneous

declarations by prescribers and the complexity of LEE011 manufacturer assessing the causality of adverse events lead to the idea that pharmacovigilance is insufficient to fully characterize the BRA during the post-marketing period.14 This can be complemented by pharmacoepidemiology studies such as observational cohort studies, also called post-approval Inhibitors,research,lifescience,medical safety studies in Europe,15 where patients are prescribed the drug of interest on purely medical grounds, without any randomization. The pharmacovigilance surveillance and the observational pharmacoepidemiology studies offer a naturalistic observational setting which is essential to build the more comprehensive safety profile post-registration and to confirm the preregistration Inhibitors,research,lifescience,medical BRA; the naturalistic setting plays a critical role lor marketed drugs. Quantitative methods for drug benefit-risk assessment There is a growing interest in quantitative estimates of the BRA,16 and we review several quantitative and semi-quantitative methods developed with this goal. Each of these methods presents advantages and limitations,

meaning that so far none has received unanimous Inhibitors,research,lifescience,medical approval nor is systematically used by regulatory authorities Inhibitors,research,lifescience,medical or by pharmaceutical industries. The methods presented provide an average BRA for a population of patients, ie, they are not intended for a benefit-risk estimation in individual patients. Number needed to treat Number needed to treat (NNT) and number needed to harm (NNH) are simple methods which are useful for assessing the BRA in a single clinical trial.17 The NNT is the number of patients who need to be treated Inhibitors,research,lifescience,medical with the drug in order to achieve one more occurrence of efficacious treatment of the disease targeted by

the drug. It is not an absolute value – the NNT depends on the conditions compared: experimental drug versus no treatment, Protein Tyrosine Kinase inhibitor or a more or less efficacious alternative. Hie NNH means the number of patients who need to be treated before one more patient will experience an ADR. The NNH:NNT ratio18 is a simple tool to measure the increase in the number ol therapeutic successes achieved for each additional ADR incurred from using the drug of interest rather than the reference treatment; it is a simple tool to assess the benefit:risk ratio. If NNILNNT is greater than 1, fewer patients need to be treated to observe a benefit from the drug than to have one additional occurrence of an ADR; in other words the BRA is positive, at least numerically.