(214) Treatment patterns in patients with dermatomyositis in the United Kingdom: a cohort study using the Clinical Practice Research Datalink

Background: Dermatomyositis (DM) is an autoimmune disease associated with muscle weakness and skin disorders leading to increased risk of morbidity and mortality. A 2022 study of 1,097 patients (mean age 54.6 years; 77% women) with myopathic DM in the United States reported that 20% of patients received ≥2 consecutive nonsteroidal immunosuppressants within 12 months post-diagnosis. The treatment patterns of patients with DM in the United Kingdom (UK) are not known.

Objectives: To describe the demographics and treatment patterns among patients with DM in the UK.

Methods: Clinical Practice Research Datalink (CPRD) GOLD and CPRD Aurum are two large, longitudinal, UK population-based primary care electronic health record databases. Based on these two data sets, a retrospective cohort of patients with DM was selected, defined by presence of a DM diagnosis (Read code N003. [Dermatomyositis) or Nyu4400 [Other dermatomyositis]) between the years 2010 and 2022. Four therapeutic drug classes were created: immunosuppressants, corticosteroids, standalone rituximab, and intravenous immunoglobulin. First line therapy was defined as the first prescription(s) for any of the listed drugs after the index diagnosis. Second- and third lines of therapy were defined as either (i) the initiation of any drug after a treatment gap of >30 days or (ii) a switch to a new drug class not used in a previous line, without regard to treatment gaps.

Results: From 2010-2022, CPRD Gold and CPRD Aurum recorded 316 patients with DM (69.9% female, median age 60 years) and 940 patients with DM (69.6% female, median age 61 years), respectively. Treatment patterns were evaluable in 224 (70.9%) patients from CPRD Gold and 486 (51.7%) patient from Aurum. Patients in both databases predominantly used ≥2 lines of therapy: 87.5% (n=196/224) of evaluable patients in CPRD Gold and 82.3% (n=400/486) in Aurum. The most common treatment pattern in Gold was three lines of corticosteroids (n=72/224, 32.1%). In Aurum, three lines of immunosuppressant therapy was most common (n=305/486, 62.8%). In 2017, the EULAR diagnostic/classification criteria for DM were updated; in a subgroup analysis from 2018-2022, there was an increase in median age observed in both Aurum and Gold. No notable changes in treatment patterns were found.

Conclusions: The demographics and treatment patterns of patients with DM in the UK were reported from two primary care electronic health record database. The majority of UK patients received ≥2 lines of therapy, characterized mainly by treatment with a selected class of corticosteroids or immunosuppressants. The use of multiple therapies suggests an unmet need for effective DM treatments.