Range and Consistency of Outcomes Reported in Randomized Trials Conducted in Kidney Transplant Recipients: A Systematic Review

Background: The potential for clinical trials to impact patient care may be limited if the outcomes reported vary by trial and lack direct relevance to patients. Despite the many trials conducted in kidney transplantation, premature death due to cardiovascular disease, infection, and malignancy remains high. We aimed to assess the range and consistency of outcomes reported in trials in kidney transplantation. Methods: We searched for randomized trials conducted in kidney transplantation. We extracted the outcome measures, classified them into outcome domains, and into categories (clinical, surrogate or patient-reported outcome [PRO]). We assessed the measures used for the top 4 domains. Results: Overall, 397 trials reported 12 047 outcomes measures and time points (median, 19 per trial; interquartile range, 9-42) across 106 different domains, of which 55 (52%) were surrogate, 35 (33%) clinical, and 16 (15%) PRO. The 4 most frequently reported were graft function (322 [81%] trials, 118 outcome measures), acute rejection (234 [59%], 93 measures), graft loss (215 [54%], 48 measures), and mortality (204 [51%], 51 measures). The remaining 102 domains were reported in less than 50% of trials. Conclusions: Mortality- and graft-related outcome domains were frequently reported and assessed with a multiplicity of measures. Most outcome domains were surrogate outcomes, and the reporting of relevant life-threatening complications and PRO were uncommon. Establishing core outcomes based on the shared priorities of patients/caregivers and health professionals in kidney transplantation may improve the relevance and consistency of outcome reporting in trials to better inform clinical decision making.