051 Differences in the response of dermatologic symptoms and muscular strength after intravenous immunoglobulin therapy in dermatomyositis patients

Abstract

Dermatomyositis (DM) is an auto-immune inflammatory myopathy characterized by muscle weakness and typical skin manifestations. Therapy includes systemic glucocorticoids, immunosuppressants and intravenous immunoglobulin (IVIG). Studies addressing the long-term efficacy of IVIG treatment are sparse. Particularly, studies investigating differences in response patterns of cutaneous and muscular symptoms are lacking. In this retrospective study we analyzed the clinical characteristics and outcomes of 20 DM patients treated between 2000-2017. The average age of patients was 62.5 (range 89-37) years. Six patients (30%) had paraneoplastic DM. Nineteen patients received glucocorticoids in addition to other immunomodulatory drugs: Fifteen patients (75%) were treated with IVIG at a dosage of 2g/kg bodyweight every 4 weeks. Four patients (20%) initially received azathioprine, and one patient was treated with glucocorticoid monotherapy. Response to treatment was individually assessed for cutaneous and muscular symptoms. Data revealed that muscular strength recovered to near baseline levels within the first 4 cycles of IVIG treatment, with the majority of patients experiencing marked improvement after the first cycle. Similarly, serum CK levels dropped from averageinitial=1138.7U/l to average4cycles=82.2U/l within the first 4 treatment cycles. In contrast, skin manifestations did not improve in the majority of DM patients. Regardless of the initial response to therapy, muscular and skin symptoms did not further improve during the course of treatment, but rather remained stable after cycle 4. None of the investigated clinical characteristics predicted a response to IVIG therapy. Similar findings were seen in patients receiving medication other than IVIG. We conclude that the initial response to treatment determines the success of therapy. Additionally, we found that muscular symptoms almost completely resolved in all patients, whereas skin symptoms were barely improved.