Provide an updated understanding of characteristics and treatment utilization among patients with dermatomyositis (DM) in the United States (US).

DM is a rare, chronic inflammatory disease primarily characterized by skin manifestations and/or progressive muscle weakness. Patients with DM were reported to have higher morbidity, hospitalization rates, and mortality than matched controls; however, more recent data on DM disease burden are warranted.

This descriptive, retrospective cohort analysis employed TriNetX US electronic medical records data from adults with myopathic DM. Key inclusion criteria were: DM diagnosis from January 2007–September 2020; age ≥18 years at diagnosis; ≥6 months of baseline data before diagnosis, ≥6 months of follow-up after the diagnosis. Assessments included medications of interest utilization rates prior to diagnosis; percentage of patients who received ≥2 consecutive unique non-steroidal immunosuppressive therapies (NS-ISTs) within 12 months of diagnosis; classification and qualification of common symptoms and comorbidities pre- vs post-DM diagnosis.

The TriNetX database contained 1097 patients with DM (mean age, 54.6 years; female, 77%). The mean observation period was 9.7 years (6.0 years pre-index; 3.7 years post-index). Prior to the DM diagnosis, 60% of patients were prescribed steroids and 24% were prescribed ≥1 NS-IST. Within 12 months of diagnosis, 20% of patients received ≥2 ISTs. A 2–3-fold increase post-index compared with pre-index was observed for a range of symptoms and comorbidities, including gastroesophageal reflux disease (43% and 22%, respectively), anxiety (25% and 13%), interstitial lung diseases (26% and 10%), and osteoporosis (21% and 6%).

Most patients received multiple ISTs to manage DM symptoms before receiving a formal diagnosis, which may have contributed to delayed diagnosis. Increased symptoms and comorbidities, substantial percentages of patients receiving ≥2 ISTs, and increased symptom/comorbidity rates post-diagnosis suggest that large unmet needs remain for earlier diagnosis and better symptom control in DM.