Transparency in Risk Communication of Trials with Time-to-event Outcomes in Medicine: A Randomized Trial

Background: Medical RCT effectiveness communication often does not fully acknowledge the temporal dimension of the trial and its impact on RCT understanding in general practitioners is unclear. The authors therefore tested how trial effectiveness information given as hazard ratio (HR), prolongated failure times (PFT), restricted mean survival times (RMST), or absolute risk reductions (ARR) affected the understanding and acceptance of the treatment effectiveness in medical general practitioners. Methods: In 2024, 250 German general practitioners completed an online experiment comparing the four different effectiveness communication formats in a within design and testing the role of an absolute reference between participants. Target outcomes were whether the group could replicate the rank order of effect sizes presented to them in a between design and their acceptance rating. Results: General practitioners did not replicate the effect size order. The same effect in the RMST format was judged less effective but more acceptable compared to the presentation in the other formats. The reference did not play a role in the evaluation of the communication. Conclusions: While general practitioners generally preferred the mean survival time format, there was no intuitive representation of effect sizes in any of the formats. The provision of further normative information in addition to the effect size on the absolute time scale may aid them to rank the effectiveness of treatments.