Evaluation of benefit-risk.

Drug authorization, prescription and utilization are all based on benefit-risk assessment. This is made difficult by the apparent lack of objective means to measure the balance and by limitations regarding each of the two items. Benefit is sometimes measured by surrogate indicators of a real clinical advantage. It is assumed to be applicable to individuals even though it is measured in populations, and is represented in different ways that may convey different messages to physicians and patients. Risks are also hard to predict on an individual level. They may also be overlooked or revealed later than benefit, thus biasing the balance for a long time. Their causal relationship with the treatment is often not fully established. The benefit-risk balance itself has no generally recognized measure. This is why benefits and risks are hard to compare; either one or both may occur in single patients, and a risk-benefit profile that is acceptable in severe diseases may not be acceptable in diseases with a favourable prognosis. Pharmacoeconomics offers promising methods of health outcomes modelling using QALYs that take into consideration quality of life as well as survival. Primarily conceived as a guide for establishing the value of a treatment, they may prove useful as a means of trading efficacy and safety. However, quality of life is not always - or adequately - assessed in clinical studies. It is also not clear which is the most appropriate model to calculate QALYs for clinical purposes and how it can be used as a predictive tool at the individual level.