Value of different nutritional and inflammatory markers for diagnosis of peritonitis in patients undergoing peritoneal dialysis

This retrospective study evaluated hematological, inflammatory, and nutritional indicators of peritonitis in 132 peritoneal dialysis (PD) patients, including 83 with confirmed peritonitis and 49 without peritonitis. The peritonitis group had a higher platelet-to-albumin ratio (PAR), neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and systemic immune-inflammation index (SIRI), but lower levels of hemoglobin, cholesterol, hematocrit, albumin, lymphocytes, triglycerides, and uric acid (all p < 0.05). Multivariate logistic regression identified hemoglobin (OR = 0.944, p < 0.05) and albumin (OR = 0.719, p < 0.01) as protective factors, and C-reactive protein (CRP; OR = 1.053, p < 0.01) as an independent risk factor. ROC analysis revealed moderate diagnostic performance for PAR (AUC = 0.700), NLR (AUC = 0.718), MLR (AUC = 0.717), and SIRI (AUC = 0.688), but the neutrophil-to-monocyte ratio (NMR) and lymphocyte-to-monocyte ratio (LMR) performed poorly. A combined PAR/NLR/MLR/SIRI model achieved an AUC of 0.798. These findings link poor nutrition and heightened inflammation to peritonitis in PD patients, suggesting blood-derived indices, such as PAR, NLR, MLR, and SIRI, may serve as adjunctive markers to assist the established diagnostic methods.