The use of nonrandomized evidence to estimate treatment effects in health technology assessment.

Health technology assessment (HTA) is increasingly informed by nonrandomized studies, but there is limited guidance from HTA bodies on expectations around evidence quality and study conduct. We developed recommendations to support the appropriate use of such evidence based on a pragmatic literature review and a workshop involving 16 experts from eight countries as part of the EU's Horizon-2020 IMPACT-HTA program (work package six). To ensure HTA processes remain rigorous and robust, HTA bodies should demand clear, extensive and structured reporting of nonrandomized studies, including an in-depth assessment of the risk of bias. In recognition of the additional uncertainty imparted by nonrandomized designs in estimates of treatment effects, HTA bodies should strengthen early scientific advice and engage in collaborative efforts to improve use of real-world data.