Kim Y, et al. - In this retrospective review of 163 patients with ANCA-associated vasculitis (AAV), researchers assessed if systemic immune-inflammation index (SII) at diagnosis is useful for approximating the cross-sectional high activity and predicting poor outcomes in immunosuppressive drug-naïve patients. They found that significant odds ratio (OR) for the cross-sectional severe AAV was demonstrated only by SII in the multivariable analysis. Cut-off of SII at diagnosis for severe AAV was 1,573.56. A significantly high relative risk (RR) of the cross-sectional severe AAV was observed among patients with SII at diagnosis ≥ 1,573.56 vs those without (RR 4.625). Significantly lower cumulative relapse free and renal survivals were observed among patients with SII at diagnosis ≥ 1,573.56 vs those without. Overall, the estimation of the cross-section severe AAV as well as the prediction of the poor outcomes in AAV patients could be achieved with SII at diagnosis.