Neutrophil to Lymphocyte Ratio as a Predictor of Long-Term Outcome in Peritoneal Dialysis Patients: A 5-Year Cohort Study

Introduction: The mortality of peritoneal dialysis (PD) patients remains high. The neutrophil to lymphocyte ratio (NLR), as an indicator of systemic inflammation, has been considered to be a predictor of cardiovascular and all-cause mortality in hemodialysis patients. The present study aims to investigate the relationship between NLR and long-term outcome in PD patients. Materials and Methods: The study included patients who initiated PD for at least 3 months between January 1, 2013, and December 31, 2015. All the patients were followed up until death, cessation of PD, or to the end of the study (June 31, 2018). NLR was calculated as the ratio of neutrophils to lymphocytes. Results: A total of 140 patients were included in this study. The median NLR reported was 2.87. Patients with lower NLR showed a higher survival rate than patients with higher NLR (log rank 6.886, p = 0.009). Furthermore, patients with higher NLR had a significantly higher cardiovascular mortality (log rank 5.221, p = 0.022). Multivariate Cox proportional hazards model showed that older age (HR 1.054, 95% CI 1.017-1.092, p = 0.004), higher Ca x P (HR 1.689, 95% CI 1.131-2.523, p = 0.010), and higher NLR (HR 2.603, 95% CI 1.037-6.535, p = 0.042) were independent predictors of increased all-cause mortality. NLR was also independently associated with cardiovascular mortality (HR 2.886, 95% CI 1.005-8.283, p = 0.039). Higher NLR (HR 2.667, 95% CI 1.333-5.337, p = 0.006), older age (HR 1.028, 95% CI 1.005-1.052, p = 0.016), and history of cardiovascular disease (HR 1.426, 95% CI 1.195-3.927, p = 0.031) were significantly independently associated with poor peritonitis-free survival in this study. Conclusions: NLR could be a strong predictor of long-term outcome in PD patients.