Neutrophil-to-albumin ratio for predicting mortality in chronic kidney diseases: A cohort study on all-cause and cardiovascular mortality from NHANES 1999 to 2018

Chronic kidney disease (CKD) significantly impacts the quality of life and survival of patients globally. The neutrophil-to-albumin ratio (NAR) is a scoring system that reflects inflammation, nutritional, and mortality risk in chronic diseases. This study aims to evaluate the role of NAR in predicting CKD mortality. Data from the NHANES 1999 to 2018 were analyzed, with participants grouped by NAR quartiles. COX regression and Kaplan-Meier curves were used to examine CKD mortality. Piecewise restricted cubic spline analysis in COX regression assessed the nonlinear relationship between NAR and mortality, alongside piecewise subgroup analyses. A total of 6042 participants were included. The Q4 exhibited significantly higher all-cause mortality (24.69% vs 33.92%, P < .001) and cardiovascular disease (CVD) mortality (11.09% vs 14.95%, P = .028) compared to Q1. Kaplan-Meier curves showed Q4 had the lowest survival rate (Log-rank P < .001). In the final adjusted model (Model 2), Q4 had significantly higher all-cause (HR = 1.53, 95% CI = 1.35-1.74, P < .001) and CVD mortality (HR = 1.54, 95% CI = 1.24-1.92, P = .003). A nonlinear relationship was found between NAR and both all-cause (P < .001, P for nonlinear = .005) and CVD mortality (P < .001, P for nonlinear = .038), with higher risks at NAR ≥ 1.9. Our study identified a complex nonlinear relationship between NAR and CKD mortality, with NAR levels negatively correlating with survival probability, particularly in higher ranges and specific high-risk populations. These findings support the use of NAR as a tool for assessing CKD mortality risk, providing insights for early prevention, prognosis assessment, and management of CKD.