Objective: Juvenile dermatomyositis (DM) is a rare chronic inflammatory disease of childhood. The clinical course of juvenile DM appears to be variable, and little is known about predictors of the disease course. The aims of this study were to describe the clinical course of juvenile DM and to determine whether early clinical and laboratory features can be used to predict the time to remission and/or the disease course.
Methods: Clinical and laboratory data from a cohort of 84 patients with juvenile DM were prospectively entered into a database (1990-2005). Remission was defined as a clinical state of no active skin rash, weakness, or elevated muscle enzyme levels for 6 months off medication. The disease course was defined as monophasic, polyphasic, or chronic. Data were reviewed at the time of diagnosis and at 3 months and 6 months after the diagnosis to determine predictors of the time to remission and/or the disease course.
Results: The median time to remission was 4.67 years. Sixty percent of patients had a chronic course, 37% a monophasic course, and 3% a polyphasic course. The presence of rash (most strongly indicated by Gottron's papules) at 3 months was the earliest predictor of a longer time to remission (relative risk [RR] 0.55 [95% confidence interval (95% CI) 0.37-0.81], P = 0.002). At 6 months, the presence of nailfold abnormalities and rash also predicted a longer time to remission (RR 0.35 [95% CI 0.14-0.74], P = 0.003). We were unable to determine a prediction model of disease course.
Conclusion: The majority of patients in our cohort had a chronic disease course. The persistence of Gottron's papules and nailfold abnormalities early in the disease course was associated with a longer time to remission.