Association between neutrophil percentage-to-albumin ratio and all-cause mortality in stroke survivors stratified by triglyceride-glucose index

The neutrophil percentage-to-albumin ratio (NPAR) is a novel inflammatory biomarker with prognostic value in critical illnesses, but its association with outcomes in stroke survivors remains unclear. No prior study has explored whether this association differs across triglyceride-glucose index (TyG) strata, a surrogate marker of insulin resistance (IR) and metabolic disturbance in cardiovascular disease. Data from the National Health and Nutrition Examination Survey 1999 to 2018 were analyzed for 1187 stroke survivors aged 40 to 80 years. Kaplan–Meier curves, multivariate Cox models, restricted cubic spline (RCS) analysis, and subgroup analyses were used to examine the relationship between baseline NPAR and all-cause mortality across TyG levels. Over a median follow-up of 86 months, 496 (41.79%) of the 1187 participants died; median survival was 133 months. Kaplan–Meier analysis showed significant mortality differences across NPAR tertiles in all participants and within intermediate- and high-IR groups (all P < .001). As a continuous variable, NPAR was significantly associated with mortality in the intermediate-risk (hazard ratio = 1.18) and high-risk (hazard ratio = 1.10) groups, but not in the low-risk group. As a categorical variable, the highest NPAR tertile (T3) was associated with higher mortality across all adjustment models in IR intermediate- and high-risk groups, whereas in the IR low-risk group, significance was observed only in the minimally adjusted model. Restricted cubic spline analysis revealed a linear association between NPAR and mortality in all participants ( P for nonlinear = .291), as well as in IR intermediate- and high-risk groups, but no association in the IR low-risk group ( P for overall = .187). Subgroup analyses showed significant interactions across TyG subgroups ( P for interaction = .047). Two sensitivity analyses confirmed the stability of the main findings. Monitoring NPAR levels alongside TyG-based stratification may facilitate comprehensive risk assessment and inform targeted management strategies for stroke survivors.