Patients with EGPA had significantly higher periostin levels when compared to previously published cohorts of healthy controls[20] (mean periostin 66 ng/ml [SD 25] vs 51 ng/ml [SD 12], p < 0.01) and patients with asthma[9] (mean periostin 66 ng/ml [SD 25] vs 51 ng/ml [SD 14], p < 0.01). Here, POSTN is linked to eosinophilic granulomatosis with polyangiitis.