Utility of the neutrophil-to-lymphocyte ratio in the prediction of anti-neutrophil cytoplasmic antibody-associated vasculitis with infection.

Abstract

This study aimed to evaluate the predictive value of the neutrophil-to-lymphocyte ratio (NLR) for infection in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Newly onset patients with AAV in China were included, and their laboratory tests and disease activity were analyzed. Based on infection, patients were divided into the infection group (A-I) and the non-infection group (A-NI). Univariable and multivariable logistic regression analyses were used to investigate variables that are independently associated with infection. In total, 418 patients were enrolled. Significantly higher white blood cell count (WBC, p < 0.001), neutrophils (p < 0.001), NLR (p < 0.001), platelet-to-lymphocyte ratio (p < 0.001), monocyte-to-lymphocyte ratio (MLR, p < 0.001), erythrocyte sedimentation rate (ESR, p = 0.032), C-reactive protein (CRP, p < 0.001), procalcitonin (PCT, p < 0.001), and Birmingham vasculitis activity score (BVAS, p = 0.005) were observed in the A-I group than in the A-NI group. It was detected that NLR (ρ = 0.273, p < 0.001), MLR (ρ = 0.153, p = 0.011), ESR (ρ = 0.143, p = 0.020), and PCT (ρ = 0.391, p < 0.001) were positively correlated with BVAS. Furthermore, NLR was not only an independent predictor of infection (adjusted OR: 1.144, 95% CI: 1.059-1.236, p = 0.001), but with the largest area under ROC curve, of which value was 0.750. Notably, the optimal cut-off value of NLR for infection was 6.01, with sensitivity of 70.07% and specificity of 71.68%. Our study demonstrated that in addition to WBC, CRP, ESR, and PCT, NLR should also be used as a beneficial inflammatory indicator to differentiate infection in newly diagnosed AAV. Key Points • NLR was a helpful inflammatory marker in differentiating infection in newly diagnosed AAV.