Platelet-to-albumin ratio: a potential biomarker for predicting all-cause and cardiovascular mortality in patients undergoing peritoneal dialysis

Background: Although peritoneal dialysis (PD) is an efficient therapy for renal replacement, the long-term survival rate of patients undergoing PD remains low. The platelet-to-albumin ratio (PAR), recently identified as a parameter of inflammatory and nutritional status, is associated with an adverse prognosis for various diseases. However, the association between the serum PAR and prognosis of patients undergoing PD is poorly understood. This study aimed to evaluate whether the PAR is a reliable predictor of cardiovascular disease (CVD) and all-cause mortality in patients undergoing PD.

Methods: This multicenter cohort study enrolled patients undergoing PD from January 1, 2009, to September 30, 2018. The patients were divided into four groups according to the quartiles of their baseline PAR. The primary endpoint was all-cause and CVD-related mortality. Cox proportional hazard models were used to determine the association between the PAR and all-cause or CVD-related mortality. The receiver operating characteristic (ROC) curve was utilized to compare the performance among PAR and other inflammatory indicators. C-statistic, net reclassification improvement (NRI), and integrated discrimination improvement (IDI) were applied to examine the incremental prognostic value of PAR compared with baseline model for predicting all-cause and CVD mortality.

Results: A total of 2825 patients were included. During the follow-up period of 47.5 ± 28.3 months, 747 (26.4%) mortality cases were observed, of which 415 (55.6%) were CVD-related. Compared with the Q1 (PAR < 4.43), placement in Q4 (PAR > 7.27) was associated with an increased risk of all-cause mortality and CVD mortality (p < 0.001). The adjusted restricted cubic spline analysis indicated that the relationship of the PAR with all-cause and cardiovascular mortality was linear (p for nonlinearity = 0.289 and 0.422, respectively). No positive correlations were shown in the interaction tests. PAR exhibited superior predictive value for mortality compared to other inflammatory indicators, with a respective AUC value of 0.611 (P < 0.001) for all-cause mortality and 0.609 (P < 0.001) for cardiovascular mortality. According to the C-statistic, continuous NRI and IDI, the addition of PAR to the baseline model yielded a moderate but significant improvement in outcome prediction.

Conclusions: The PAR is an independent prognostic factor associated with all-cause and cardiovascular mortality in patients undergoing PD.