Better defining target populations for drugs with a view to reimbursement.

Reimbursement of drugs by public or private insurance systems is increasingly problematic, including in supposedly "rich" countries. There is an international consensus to consider the benefit of a Health technology assessment to clarify decisions on reimbursement by the collectivity, and this includes taking account of the target population of the new drug. The authors debate about the urgent need of a better quantification of the target population, which must include a qualitative description of this target population and a scientific extrapolation of the target population, which is certainly the most challenging problem.