INTERMEDIATE AND SURROGATE OUTCOMES IN CL INICAL-EVALUATION OF DRUGS

The development and evaluation of new drugs often rely on surrogacy. A n intermediate outcome becomes a surrogate outcome if it fulfils certa in criteria: it should be easier to measure compared with the clinical outcome, a statistical relationship should exist between the clinical outcome and the surrogate outcome, a relation should exist allowing p rediction of the degree of clinical effect based on tile measured effe ct on the surrogate outcome. Development and authorization of drugs to day often rely on so-called surrogate outcomes. Is this use sound? The validity of such outcomes has been reviewed in different therapeutic areas: hypertension, venous thromboembolism, AIDS, osteoporosis, hepat itis C. Based on this review, a pragmatic strategy is proposed which a llows for the validation and proper use of surrogate outcomes.