Abstract
BACKGROUND: Limited studies describe the longitudinal course of cutaneous dermatomyositis (DM). OBJECTIVE: To characterize disease course in treated cutaneous DM by using the Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI), a validated outcome instrument. METHODS: A retrospective cohort included patients with DM who had their CDASI activity subscore recorded for at least 2 years. Disease progression was classified as improved, worsened, or stable, and disease course was classified as monophasic, polyphasic, or chronic. Subjects were divided into groups with disease of mild (n = 16) and moderate-to-severe (n = 24) baseline severity. RESULTS: A total of 40 patients with DM met inclusion criteria. The majority demonstrated improvement in disease activity (n = 21 [52.5%]) rather than worsening (n = 7 [17.5%]) and stable (n = 12 [30.0%]) disease. Most patients with mild disease remained stable (n = 10 [62.5%]), whereas most with moderate-to-severe disease improved (n = 19 [79.2%]). A polyphasic course (n = 33 [82.5%]) predominated over monophasic (n = 5 [12.5%]) and chronic (n = 2 [5%]) courses. The average number of flares per year per number of years of follow-up was independent of baseline disease activity. LIMITATIONS: The retrospective design, potential referral bias, and cutoff values in classification criteria are limitations. CONCLUSION: Baseline CDASI activity score is associated with particular patterns of disease course and progression in cutaneous DM.