Overall, 74 (71.2%) patients achieved negative conversion of their MPO-ANCA levels (17 [81.0%], sinusitis; 57 [68.7%], non-sinusitis; P = 0.267) (Table 1), and in the remaining 31 (29.8%) patients, the MPO-ANCA levels decreased compared to the baseline levels, regardless of whether the negative conversion was achieved or not. Here, MPO is linked to sinusitis.