Neutrophil percentage-to-albumin ratio increases the risk of Parkinson’s disease and all-cause mortality in Parkinson’s disease patients: A population-based Study

Background: This study aims to investigate the association of neutrophil percentage-to-albumin ratio (NPAR) with Parkinson’s disease (PD) prevalence and all-cause mortality risk in PD patients. Methods: Using NHANES 2001-2018 data (n=25,170; 309 PD patients), weighted multivariate logistic regression and Cox regression analyses were applied to evaluate the associations between NPAR and the prevalence of PD, as well as between NPAR and all-cause mortality risk. Restricted cubic spline (RCS) analysis elucidated the precise relationships. Consistency of results was checked through subgroup analysis. Results: The mean NPAR was higher in PD (14.78±0.21) vs. that in non-PD (14.01±0.03; p < 0.001). After adjusting all variables, each unit increase in NPAR corresponded to 8% higher PD odds (OR=1.08, 95%CI:1.02-1.15, p=0.01). The prevalence of PD in the highest quintile (Q3) was 1.54 times higher than that in the lowest quintile (Q1) (OR=1.54; 95% CI, 1.02-2.34, p=0.042). The RCS analysis confirmed a linear dose-response relationship (non-linear p=0.8598), with PD risk increasing progressively at NPAR levels above approximately 13.95 (P-overall=0.0217). For all-cause mortality in PD patients, NPAR was also significantly associated. In the fully adjusted model, each unit increase in NPAR was linked to a 9% higher hazard of death (HR=1.09, 95%CI: 1.02–1.17, p=0.015), and patients with highest Q3 had an 85% higher mortality risk compared to the Q1 (HR=1.85, 95% CI: 1.03–3.33, p=0.040). Furthermore, Kaplan-Meier analysis demonstrated that PD patients in the Q1 exhibited the highest survival rates (Log-rank test, p=0.042). RCS analysis revealed a linear association (non-linear p=0.1835) for mortality, with increased risk evident above NPAR levels of approximately 14.6 (p-overall=0.0145). Subgroup analyses and interaction tests demonstrated the robustness of this association (p-interaction>0.05). Conclusions: NPAR exhibits a linear, positive association with PD risk in the general population and with all-cause mortality in PD patients. Higher NPAR levels, particularly above 13.95 for PD risk and 14.6 for all-cause mortality, are associated with increased risk. These findings highlight the potential of NPAR as a biomarker for risk stratification and prognosis in PD.