Limitation of Terminal Serum Creatinine as a Kidney Donor Profile Index Variable in Predicting Long-Term Kidney Transplant Outcomes

Background. Donor final serum creatinine (SCr) is a dynamic variable and is 1 of 10 factors used in calculating kidney donor profile index (KDPI). We hypothesize that deceased-donor kidneys (DDKs) with higher SCr were likely accepted for transplantation if procurement biopsy findings were favorable and with long-term outcomes no worse than kidneys with lower final SCr within a KDPI group. Methods. Using the Organ Procurement and Transplant Network/United Network for Organ Sharing database, we identified DDK transplant recipients from 2000 to 2015 who received induction and calcineurin inhibitor/mycophenolate mofetil maintenance. Patients were divided into 4 KDPI groups: 0-20%, 21%-50%, 51%-85%, and >85%. In each KDPI category, long-term outcomes were compared, with the use of Cox models, between patients who received kidneys with final SCr >2 versus <= 2 mg/dL. Results. A total of 59,644 patients were divided into KDPI groups 0-20% (SCr >2 mg/dL, n = 478; SCr <= 2 mg/dL, n = 14,769), 21%-50% (SCr >2 mg/dL, n = 1,592; SCr <= 2 mg/dL, n = 17,762), 51%-85% (SCr >2 mg/dL; n = 1,388, SCr <= 2 mg/dL, n = 18,024), and >85% (SCr >2 mg/dL, n = 349; SCr <= 2 mg/dL, n = 5,282). Adjusted overall graft failure risks (hazard ratio [HR] 0.88, P -= .04; HR, 0.86, P = .007) and patient death risks (HR, 0.86, P = .04; HR, 0.84, P = .01) for final SCr >2 versus <= 2 mg/dL groups were lower in KDPI categories 21%-50% and 51%-85%, respectively, with similar death-censored graft failure risks. Discussion. Outcomes of transplanting DDKs with elevated final SCr are no worse than transplanting kidneys with lower final SCr, highlighting the limitation of the single value of final SCr as a variable for calculating KDPI.