Objective: 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).
Methods: 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.
Results: 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%.
Conclusion: 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.
Keywords: ANCA-associated vasculitis; Infection; Neutrophil-to-lymphocyte ratio.
© 2022. The Author(s), under exclusive licence to International League of Associations for Rheumatology (ILAR).