Variability in the reporting of renal function endpoints in immunosuppression trials in renal transplantation: time for consensus?

Early measures of graft function are increasingly used to assess efficacy in clinical trials of kidney transplant immunosuppression. This study aimed to assess the variability and quality of reporting of these endpoints in contemporary trials. Data regarding renal function endpoints were extracted from 213 reports from randomized controlled trials comparing immunosuppressive interventions in renal transplant recipients published between 2010 and 2014. A total of 174 (81.7%) reports included a measure of renal function; in 44 (20.7%), this was the primary endpoint. A total of 103 manuscripts (48.4%) reported serum creatinine, 142 (66.6%) reported estimated glomerular filtration rate (eGFR), and 26 (12.2%) reported measured GFR. Formulas used for GFR estimation were modification of diet in renal disease (42.3%), Cockroft-Gault (23.5%), Nankivell (15.0%), and CKD-EPI (0.9%). Six studies (2.8%) did not report the formula used to estimate GFR. A total of 13.9% of endpoints had missing data. In 10 studies, disagreement was found in the significance of findings using different measures of renal function. There is a great deal of variability in the reporting of renal function endpoints, with a significant proportion of studies using underperforming or inappropriate estimates. There is a need for consensus as to the best tool for monitoring and reporting renal function post-transplant, and in particular for use in clinical trials and registries.