Evolution of Endpoints for Renal Transplant Outcome

Progressive improvement in short-term kidney transplant survival and reduction in acute rejection rates have restricted our ability to assess newer therapy. Past and present conventional endpoints, such as short-term graft survival and acute rejection rates, are no longer practical. This has prompted investigators to search for alternative endpoints. Long-term graft survival is an ideal endpoint. However, this requires a large cohort of patients with longer follow-up. A simpler approach would be to identify short-term markers, which can predict long-term survival. Short-term potential markers that can predict long-term survival are: clinical (renal function), histological (renal pathological markers) and immunological (anti-donor antibody, blood and urine cytokines). Post-transplant renal function estimated by serum creatinine, cystatin C and creatinine clearance within 1 year, and histological indices, as the Banff chronicity score, have the potential to predict long-term graft survival. Serum creatinine is limited as a marker by its variability based on recipient age, body weight, race and sex. Histological indices are limited, due to the invasive nature of evaluation. Post-transplant renal function and histological indices can be used potentially as a composite endpoint, in combination with conventional endpoints, such as graft loss, death and acute rejection. A practical approach for assessing newer therapies in future studies is to use composite endpoints, which combine conventional endpoints (graft loss, death, acute rejection) with newer endpoints (renal function, histological indices).