Pretransplant C-reactive protein-to-albumin ratio predicts mortality in kidney transplant recipients: a retrospective cohort study.

Background: The C-reactive protein (CRP)-to-albumin ratio (CAR) is a more effective prognostic indicator than CRP or albumin alone in various diseases. This study aimed to evaluate the predictive value of the CAR for mortality in kidney transplant recipients (KTRs). Methods: A total of 924 patients who underwent their first kidney transplantation at Kyungpook National University Hospital during 2006-2020 were enrolled and classified into quartile (Q) groups according to their pretransplant CAR values. A Cox regression analysis was conducted to analyze the hazard ratios (HRs) of mortality. Results: Fifty-nine patients died during the posttransplant period (mean, 85.2±44.2 months). All-cause mortality (Q1, 3.0%; Q2, 4.8%; Q3, 7.8%; Q4, 10.0%; P for trend <0.001) and infection-related mortality increased linearly with an increase in CAR (P for trend=0.004). The Q3 and Q4 had higher risks of all-cause mortality than Q1 after adjusting for confounding factors (Q3 adjusted HR [aHR] 2.49, 95% confidence interval [CI] 1.04-5.99, P=0.041; Q4 aHR 3.09, 95% CI 1.31-7.27, P=0.010). Q4 was also independently associated with infection-related mortality (aHR 5.83, 95% CI 1.27-26.8, P=0.023). The area under the curve of the CAR for all-cause and infection-related mortality was higher than that of CRP or albumin alone. There was no association between CAR and death-censored graft failure or acute rejection. Conclusions: A higher pretransplant CAR increases the risk of posttransplant mortality, particularly infection-related, in KTRs. Pretransplant CAR can be an effective and easily accessible predictor of posttransplant mortality.