Clinical features and outcome in a Danish cohort of juvenile dermatomyositis patients

Objective To assess disease characteristics and outcome in Danish juvenile dermatomyositis (JDM) patients (1977-2007). Methods Medical record review of hospital records identified from the National Patient Register. Results Fifty-seven JDM patients were identified. Follow-up time was 7 years (range 0.06-30). Female:male ratio was 2.5:1. Mean age at disease onset was 7 years (SD +/- 3.7), range 1.5-16.0 years. Diagnostic delay was 0.7 years (SD +/- 1.6), range 0.04-9 years. Mean disease duration was 3.7 years (SD +/- 3.5), range 0.7-9 years. Thirty-nine patients (70%) were in full remission. Three patients (5%) were deceased. Disease/treatment-induced damage was present in 35 (61%) patients. Decreased pulmonary function occurred early in the disease course (median 10 months), osteoporosis and calcinosis occurred later (median 18 and 22 months). Four patients developed persistent damage within the first 6 months, four developed calcinosis within the first year. Shorter disease duration was associated with less damage (p=0.004). In a multivariate assessment analysis age > 10 years at disease onset was associated with more damage (p < 0.01), OR 10.96 (CI 1.6-73.6), and disease duration > 4 years was associated with calcinosis (p=0.01) OR 23.2 (CI 2.6-206.2). Conclusion We present a nationwide retrospective study of Danish JDM patients from 1977-2007. Although 70% were in remission, 61% of the patients had clinical signs of damage. Only a few patients developed damage within the first year of the disease. Longer disease duration and higher age at disease onset was correlated with more disease damage.