Abstract
The relationship between neutrophil percentage to albumin (NPAR) index and mortality in patients with diabetic kidney disease (DKD) remains unclear. This study aimed to investigate this association by designing a nationally representative longitudinal cohort. We conducted a longitudinal cohort analysis of 1778 adults with DKD from the National Health and Nutrition Examination Survey (2009-2018) with linkage to mortality data through December 31, 2019. Multivariate Cox proportional hazards models were conducted to explore the correlation between the NPAR index and all-cause and cardiovascular disease (CVD) mortality. A restricted cubic spline analysis was performed to explore the potential nonlinear relationship. Additionally, subgroup and sensitivity analysis were conducted to ensure the robustness of the findings. Over a median follow-up of 71 months (84,604 person-years), 462 all-cause and 146 CVD deaths occurred. Compared to the lowest quartile, participants in the highest NPAR quartile had significantly increased risks of all-cause (hazard ratio 1.96, 95% confidence interval 1.49-2.58, P < .001) and CVD mortality (hazard ratio 3.62, 95% confidence interval 2.04-6.41, P < .001). Restricted cubic spline analysis revealed a J-shaped relationship between NPAR and all-cause mortality (P for nonlinearity < .001), whereas NPAR showed a linear positive association with CVD mortality (P for nonlinearity = .4771). These findings remained consistent across subgroup and sensitivity analysis. Higher NPAR is independently associated with increased risks of all-cause and cardiovascular mortality in adults with DKD, supporting its potential role as a prognostic biomarker.