Uncertainty in Long-Term Relative Effectiveness of Medicines in Health Technology Assessment

Objectives: Uncertainty regarding the long-term relative effectiveness is an important factor in health technology assessment (HTA) of medicines. This study investigated how different HTA bodies address this uncertainty in their assessments. Methods: A total of 49 HTA reports from 6 national HTA bodies, assessing 9 medicines for spinal muscular atrophy, cystic fibrosis, and hypercholesterolemia, were included. In these reports, 81 relative effectiveness assessments and 45 cost-effectiveness assessments were performed on an indication level. We collected information on included trials, assessment outcomes, uncertainty regarding the long-term effectiveness, proposed managed entry agreements, and reassessments. Results: Uncertainty regarding the long-term effectiveness was an important consideration in almost all cost-effectiveness assessments (91%) and three-quarters of relative effectiveness assessments (74%), despite differences in methodologies among HTA bodies. There were considerable differences in the amount and type of long-term effectiveness data included by HTA bodies due to timing and inclusion criteria. In total 23 managed entry agreements were proposed of which 14 were linked to uncertainty regarding the long-term effectiveness. In addition, 13 reassessments were performed of which 4 led to an increase in patient access because of more available long-term effectiveness data. Conclusions: Uncertainty regarding the long-term effectiveness is an important challenge for HTA bodies. There are large differences in the acceptance of evidence among HTA bodies, which leads to heterogeneity in the inclusion of available long-term effectiveness data for decision making. In cases with large uncertainty regarding the long-term effectiveness, outcome-based agreements and reassessments are used by HTA bodies, but differently between HTA bodies and indications.