Cutaneous dermatomyositis disease course followed over time using the Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI)

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.