Platelet to lymphocyte ratio is associated with the current activity of ANCA-associated vasculitis at diagnosis: a retrospective monocentric study

Platelet to lymphocyte ratio (PLR) has been introduced as a useful index to estimate the current inflammatory burdens in various diseases. In this study, we investigate whether PLR is associated with the severity of ANCA-associated vasculitis (AAV). We retrospectively reviewed the medical records of 163 patients with AAV, collected clinical, laboratory and radiological data and calculated Birmingham vasculitis activity score (BVAS). We defined the lower limit of the highest tertile of BVAS as the cut-off for severe AAV (BVAS ≥ 16). The optimal cut-off of PLR for severe AAV was set as 272.0. The odds ratio (OR) of PLR for severe AAV was assessed using the univariable and multivariable logistic regression analyses. The median age at diagnosis was 58.0 years and 51 patients (31.3%) were men. Patients with severe AAV exhibited higher rate of ANCA positivity and higher blood urea nitrogen (BUN), creatinine (Cr), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) than those without. Patients with severe AAV exhibited significantly increased median PLR compared to those without (299.3 vs. 184.0). In the univariable binary logistic regression analysis, BUN ≥ 17.45 mg/dL (OR 3.730), Cr ≥ 1.12 mg/dL (OR 3.519), ESR ≥ 83.5 mm/h (OR 2.785), CRP ≥ 20.0 mg/L (OR 2.612), PLR ≥ 272.0 (OR 4.231) and ANCA positivity (OR 2.306) were associated with severe AAV. In the multivariable binary logistic regression analysis, only PLR ≥ 272.0 was an independent predictor of severe AAV at diagnosis (OR 2.734, 95% CI 1.247, 5.993). In conclusion, PLR at diagnosis is associated with the current activity of vasculitis in AAV patients.