Use of Surrogate end points in HTA

The different actors involved in health system decision-making and regulation have to deal with the question which are valid parameters to assess the health value of health technologies. So called surrogate endpoints represent in the best case preliminary steps in the casual chain leading to the relevant outcome (e. g. mortality, morbidity) and are not usually directly perceptible by patients. Surrogate endpoints are not only used in trials of pharmaceuticals but also in studies of other technologies. Their use in the assessment of the benefit of a health technology is however problematic. In this report we intend to answer the following research questions: Which criteria need to be fulfilled for a surrogate parameter to be considered a valid endpoint? Which methods have been described in the literature for the assessment of the validity of surrogate endpoints? Which methodological recommendations concerning the use of surrogate endpoints have been made by international HTA agencies? Which place has been given to surrogate endpoints in international and German HTA reports? For this purpose, we choose three different approaches. Firstly, we conduct a review of the methodological literature dealing with the issue of surrogate endpoints and their validation. Secondly, we analyse current methodological guidelines of HTA agencies members of the International network of agencies for Health Technology Assessment (INAHTA) as well as of agencies concerned with assessments for reimbursement purposes. Finally, we analyse the outcome parameter used in a sample of HTA reports available for the public. The analysis of methodological guidelines shows a very cautious position of HTA institutions regarding the use of surrogate endpoints in technology assessment. Surrogate endpoints have not been prominently used in HTA reports. None of the analysed reports based its conclusions solely on the results of surrogate endpoints. The analysis of German HTA reports shows a similar pattern. The validation of a surrogate endpoint requires extensive research, including randomized controlled trials (RCT) assessing clinical relevant endpoints. The validity of a surrogate parameter is rather technology-specific than disease-specific. Thus – even in the case of apparently similar technologies – it is necessary to validate the surrogate for every single technology (i. e. for every single active agent). The use of surrogate endpoints in the assessment of the benefit of health technologies is still to be seen very critically.