OBJECTIVES: To describe the treatment patterns and economic burden of dermatomyositis (DM) and polymyositis (PM) using data from a large, commercial insurance database in the United States. Existing data are relatively scarce and outdated.

METHODS: Adults with ≥1 inpatient diagnosis or ≥2 outpatient diagnoses (30–365 days apart) of DM or PM between 1 January 2018 and 30 June 2021 were selected from the Merative™ MarketScan® claims database. The frequency and rate of dispensed prescriptions, comorbidities, annualized health service utilization, and annualized direct healthcare costs were described.

RESULTS: The study included 3693 DM patients and 2841 PM patients (median follow-up: 1.39 and 1.35 years, respectively). Glucocorticoids were the predominate treatment for both DM (78.3%) and PM (78.5%), and immunosuppressants were used in over half of patients (DM: 54.2%; PM: 53.5%). Oral glucocorticoids were the most common first-line therapy in incident patients (DM: 12.8%; PM: 24.3%). Cardiovascular events were the most common comorbidity, reported by 49.2% and 63.7% of patients with DM and PM, respectively. Hyperlipidemia (DM: 39.2%; PM: 49.8%) and vitamin D deficiency (DM: 31.4%; PM: 32.9%) were also frequently reported. The mean number of annualized outpatient visits were 36.1 and 42.3 for patients with DM and PM, respectively. Hospitalization was required for 21.6% of DM patients (mean duration 19.2 days) and 29.1% of PM patients (21.9 days). Mean (median) annualized direct costs were $73,673 ($17,290) for DM and $92,380 ($24,261) for PM, driven largely by outpatient claims (DM: 56.0%; PM: 45.4%).

CONCLUSIONS: Our study showed that glucocorticoids were the primary treatment for DM and PM and that overall costs, driven largely by outpatient charges, were higher than previously reported. These data provide an important update on the treatment landscape for DM and PM in the United States.