Proposed consensus for definitions and endpoints for clinical trials of acute kidney transplant rejection

Progress in transplantation therapeutics requires validation from multicenter trials in which enrollment criteria and endpoint definitions have been standardized. A database of acute rejection was established from 19 North American, European, and Australian transplant centers and included parameters on rejection diagnosis and treatment of 50 consecutive rejection episodes from each center. Patient demographics, induction and maintenance immunosuppressive therapies, antirejection agents (drug, dose, duration), clinical signs (decrease in urine volume, presence of fever of ≤38.5°C), serum creatinine concentration (nadir, at rejection, dally during antirejection therapy to 15 days, and days 30, 90, 180, and 365 after rejection date), rejection biopsy findings, morbidity, recurrence of rejection, and renal function at 1 year were recorded for 953 rejection episodes. From these data, three definitions were proposed. Acute rejection was defined as an immunologic process resulting in a serum creatinine increase of ≤0.4 mg/dL, with or without clinical signs, and should include a biopsy confirmation that has been standardized to the Banff criteria. Corticosteroid-resistant rejection was defined as a rejection episode in which a minimum of 250 to 1000 mg of methylprednisolone administered as initial therapy falls to result in stabilization or reduction of the serum creatinine after 3 days of corticosteroid treatment. Successful response to therapy was defined as a serum creatinine level ≤110% of the serum creatinine on the day of the rejection diagnosis and a return of the serum creatinine to or below the rejection creatinine level by 5 days of therapy with maintenance of this response for a minimum of 30 days. The work represented in the Efficacy Endpoints Database provides a step toward improving definitions in clinical trials. Continuity in clinical trial design should lead to improvements in evaluation of outcomes and, thereby have an effect on clinical practice.