[Relevance of different study types in benefit assessment: Results from expert interviews]

Background: Careful evaluation of new interventions is essential. Randomized controlled trials (RCTs) and systematic reviews of RCTs provide the most reliable evidence base in comparative evaluations of treatments and interventions. Observational study designs are found at the lower levels of the classical evidence hierarchy. In light of policy efforts to accelerate the availability of innovations, the use of evidence from non-randomized studies for reimbursement decisions is being discussed. The present study addresses the question of the value and feasibility of RCTs and observational studies for benefit assessment after an intervention has been introduced into practice.

Methods: Experts from German-speaking countries were interviewed using qualitative, semi-structured interviews. Participants included experts in health economics, health services and health services research, health communication, ethics, and health policy. The interviews were conducted by one researcher and then analyzed using a deductive approach. Main categories and subcategories were extracted.

Results: Twenty-six experts were invited to participate, and 15 agreed to be interviewed. The duration of the individual interviews varied between 35 and 80minutes. The interviewed experts considered it possible and necessary to conduct RCTs when an intervention is already available in care in order to demonstrate that an intervention is more effective than existing alternatives. Experts considered good study design, methodological knowledge of those conducting the study, infrastructure, and funding as underlying conditions. They emphasized that the benefit of an intervention cannot be conclusively clarified on the basis of observational studies and that RCTs can therefore only be dispensed with in exceptional cases. Therefore, observational studies do not represent an alternative to RCTs in benefit assessment in general. In the opinion of the experts, the requirements for observational studies included sensible criteria and quality assurance measures. As alternatives to RCTs, the experts named studies based on routine data or high-quality, prospective, comparative cohort studies. Individual experts were very critical of studies based on data from registries.

Discussion and conclusion: The results of the interviews are underlined by findings from the scientific literature. For example, international scientists advocate for conducting RCTs instead of observational studies and for a reduction in hurdles and barriers for conducting RCTs. In international methodological standards for the preparation of health technology assessments, RCTs are also generally preferred for benefit assessment. Nevertheless, there is still a need for research about the optimal use of observational studies, alternative RCT designs and the use of data from routine care or registries, as policy makers, among others, believe that observational studies should be used for benefit assessment. The results show that experts still adhere to the established principles of clinical epidemiology. Observational studies should only be used as an alternative to RCTs in exceptional cases to examine whether one intervention is more effective than existing alternatives.