In this study, the most common surrogate markers defined in the EMA algorithm were fixed pulmonary infiltrates, nodules, or cavitation present for >1 month (78 % in PR3-ANCA positive cases and 86 % in MPO-ANCA positive cases, respectively), followed by bronchial stenosis (33 % and 50 %, respectively) and chronic sinusitis, otitis media, or mastoiditis for >3 months (56 % and 67 %, respectively) (Table 6). Here, MPO is linked to sinusitis.