The relationship between neutrophil-to-lymphocyte ratio and the first occurrence of pneumonia in peritoneal dialysis patients

Background Although neutrophil-to-lymphocyte ratio (NLR) is closely associated with pneumonia in the general population, its relationship is unclear in peritoneal dialysis (PD) patients. Methods This is a cohort study consisting of 739 PD patients and dividing into two groups. Kaplan-Meier curves were applied to observe the incidence of the first occurrence of pneumonia, competitive risk analysis was conducted to compare whether there was a significant difference in each NLR group in the presence of other competing events, multivariable COX regression analysis was used to evaluate the hazard ratios (HRs), as well as forest plot was used to analyze the relationship between NLR and the first occurrence of pneumonia in different subgroups. Results Of all the patients, 116 cases of first-time pneumonia were recorded. The first-time pneumonia incidence rate was 71.67/1000 patient-years in high NLR group, which was markedly higher than that of 45.81/1000 patient-years in low NLR group. Kaplan-Meier curves indicated significant differences in the incidence of the first occurrence of pneumonia between two groups (log-rank test p = 0.015). The competitive risk model suggested a significant difference in the cumulative incidence of first pneumonia between the two groups (p = 0.032). Compared to low NLR group, adjusted Cox model showed that high NLR group was associated with increased risk of pneumonia incidence (HR, 1.51; 95% CI 1.04-2.21; p = 0.031). Forest plot showed no interaction was found in subgroups. Conclusions The risk of pneumonia was significantly increasing in PD patients with high NLR, which may have a certain guiding significance for the clinic.