Impact of sex on the association between neutrophil percentage-to-albumin ratio and mortality in perioperative patients with chronic kidney disease: a retrospective analysis of the INSPIRE database

This research assessed the relationship between the neutrophil percentage-to-albumin ratio (NPAR) and mortality in perioperative chronic kidney disease (CKD) patients and explored sex-specific differences. Using the INSPIRE database (2011–2020), we retrospectively analyzed 2,474 surgical CKD patients that were categorized by admission NPAR tertiles. Cox regression was used to evaluate associations between the NPAR and mortality, and stratified curve fitting was used to reveal sex-specific differences. Analysis of the cohort (mean age 60.8 ± 14.8 years; 65.3% male) revealed that an elevated NPAR was significantly associated with increased mortality risk, particularly in females. For in-hospital mortality, each unit increase in the NPAR (continuous) significantly predicted risk in females across all models (Model 4: HR = 2.56, 95% CI 1.73–3.78, p < 0.001) with the highest tertile (T3) showing a significantly increased risk in the fully adjusted models (T3 vs. T1, Model 4: HR = 2.93, 95% CI 1.48–5.80, p = 0.002). However, this association was not significant in males. For 30-day mortality, the association was even stronger in females (NPAR continuous, Model 4: HR = 4.13, 95% CI 2.61–6.52, p < 0.001; T3 vs. T1, Model 4: HR = 10.87, 95% CI 4.46–26.51, p < 0.001), while males showed no significant association even after full adjustment. Additionally, significant sex-specific interactions were observed for both outcomes (p < 0.05 for trend differences). Our findings indicate that an elevated NPAR is significantly associated with higher in-hospital and 30-day mortality in female CKD patients who have undergone surgery but this association is not significant in males.