Complete remission and relapse in the treatment of idiopathic inflammatory myopathies: a retrospective cohort study.

OBJECTIVES: To investigate the achievement of complete remission (CR) and the management for relapsed cases in the treatment of idiopathic inflammatory myopathies (IIM). METHODS: A total of 132 patients were retrospectively analysed. CR was defined as no evidence of disease activity in all involved organs for a continuous period of six months. Relapse was defined as a dose increase of glucocorticoid (GC) more than 50% and an increase in prednisolone (PSL) equivalent to more than 0.4 mg/kg/day. Clinical data were collected by electrical chart review. RESULTS: Eighty-eight (66.7%) patients achieved CR with an initial treatment. Forty-three patients experienced at least one relapse. Anti-ARS antibody was positively and achieving CR was negatively associated with relapse (HR 3.02 and OR 0.17, respectively). Re-induction therapies were classified into three groups: high-dose GC plus one immunosuppressant (IS)/biologics (H+1IS, n=12), moderate-dose GC plus two IS/biologics (M+2IS, n=12), and moderate-dose GC plus one IS/biologics (M+1IS, n=19). The frequency of second relapse was least in M+2IS regimen. Concomitant use of two IS/biologics did not increase the incidence of severe adverse events. CONCLUSIONS: CR was achieved in two-thirds of IIM patients. Achieving CR was protective for relapse. Combination therapy with two IS/biologics might be preferable in relapsed cases.