The prognostic value of the neutrophil percentage-to-albumin ratio for all-cause and cardiovascular mortality in chronic kidney disease: A retrospective cohort study using NHANES 1999 to 2018

Chronic kidney disease (CKD) is a global public health challenge associated with elevated all-cause and cardiovascular mortality, driven by chronic inflammation and malnutrition. The neutrophil percentage-to-albumin ratio (NPAR), integrating inflammatory, and nutritional markers, has shown prognostic value in other conditions but remains underexplored in CKD. This study aimed to evaluate the association between NPAR and mortality outcomes in CKD patients using a nationally representative cohort. Data from National Health and Nutrition Examination Survey 1999 to 2018 were analyzed, including 1990 adults with CKD. NPAR was calculated as neutrophil percentage divided by serum albumin and categorized into quartiles. Primary outcomes were all-cause and cardiovascular mortality, assessed via linkage with the National Death Index. Cox regression models adjusted for demographics, comorbidities, and laboratory parameters. Restricted cubic splines and mediation analyses explored dose-response relationships and underlying mechanisms. Higher NPAR quartiles were significantly associated with increased all-cause mortality (Q4 vs Q1: adjusted hazard ratio = 2.04, 95% confidence interval = 1.41-3.00, P < .001) and cardiovascular mortality (Q4 vs Q1: hazard ratio = 2.33, 95% confidence interval = 1.20-4.50, P = .012). Kaplan-Meier analysis revealed poorer survival in Q4 (P < .001). Subgroup analyses showed stronger NPAR-mortality associations in obese, hypertensive, and cardiovascular disease patients. Mediation analysis indicated no significant role of estimated glomerular filtration rat in these relationships. NPAR is an independent predictor of all-cause and cardiovascular mortality in CKD, particularly in high-risk subgroups. This biomarker may enhance risk stratification by reflecting combined inflammatory and nutritional dysfunction, supporting targeted interventions to improve outcomes. Further prospective studies are needed to validate its clinical utility.