Arthritis Rheum 65 (1): 1 - 11, 2013. doi: 10.1002 / art.37715 Treatment of EGPA Corticosteroids Systemic corticosteroids plus an immunosuppressant are the mainstay of treatment of eosinophilic granulomatosis with polyangiitis (EGPA) because corticosteroids alone often do not sustain remission, even if there are no poor prognostic factors.