Association of the Neutrophil Percentage-to-Albumin Ratio with All-Cause Mortality in Patients with Hypercapnic...

The neutrophil percentage-to-albumin ratio (NPAR) has emerged as a widely used inflammatory marker for predicting clinical outcomes across various diseases; however, its prognostic value in hypercapnic respiratory failure (HRF) remains uncertain. This study aimed to examine the association between NPAR and all-cause mortality in patients with HRF.

This prospective cohort study enrolled 561 HRF patients hospitalized at Yancheng First People's Hospital between October 2020 and September 2021. The primary outcome was 24-month all-cause mortality; secondary outcomes included mortality at 3, 6, and 12 months. The association between NPAR and all-cause mortality was assessed using restricted cubic spline (RCS) modeling, multivariate Cox proportional hazards models, Kaplan-Meier survival analysis, and subgroup analyses. Discriminatory performance was evaluated using the area under the receiver operating characteristic curve (AUC).

RCS modeling demonstrated a significant linear association between NPAR and all-cause mortality in HRF patients (P for overall association < 0.001). Both the Cox models and Kaplan-Meier analyses indicated that elevated NPAR levels were significantly associated with increased 3-, 6-, 12-, and 24-month all-cause mortality (all P < 0.05). Subgroup analysis further supported an independent association between NPAR and mortality. The AUC for NPAR in predicting 12-month all-cause mortality was 0.66 (95% confidence interval [CI], 0.61-0.71), which was significantly higher than that of neutrophil percentage or albumin alone (AUC =0.62; 95% CI, 0.57-0.67; P < 0.05).

Elevated NPAR is independently associated with increased all-cause mortality in patients with HRF. As a composite marker reflecting both systemic inflammation and nutritional status, NPAR may serve as a robust prognostic indicator to enhance risk stratification and guide clinical decision-making in HRF management.