Objective: To evaluate a group of 53 patients with juvenile dermatomyositis (JDM), on average 13.9 years after disease onset, in order to describe the long-term disease outcome and to identify disease-related parameters associated with poor disease outcome.
Methods: Baseline information at disease onset was obtained from medical records. Disease status at follow-up was evaluated by physical examination. The Myositis Damage Index (MDI) and the Myositis Disease Damage by Visual Analogue Scale (MYODAM-VAS) were used to describe disease damage.
Results: Disease damage was seen in 60.4% of patients. The most common damage was cutaneous scarring (39.6%) and muscle dysfunction (34%). Calcinosis was found in 20%, lipodystrophy in 13%, and severe damage affecting more than two organ systems in 24.5% of patients. A disease duration > 4 years increased the risk of damage based on: MDI score [adjusted odds ratio (AOR) 8.3, 95% confidence interval (CI) 1.7-41.7], MYODAM-VAS score (AOR 26.2, 95% CI 3.1-223.7), and number of affected organs (AOR 16.3, 95% CI 1.1-232.4). Disease onset age ≥ 7.4 years increased the risk of more than two affected organs (AOR 15.8, 95% CI 1.9-129.4). Disease duration ≥ 4 years increased the risk of calcinosis (OR 4.8, 95% CI 1.1-20.9) and continuous muscle dysfunction (OR 4.2, 95% CI 1.1-17.3).
Conclusion: In a long-term follow-up study, 60% of JDM patients had disease damage at a mean of 14 years after disease onset. Longer disease duration was the most important predictor of damage, calcinosis, and impaired muscle function, and higher age at disease onset predicted more organs involved at follow-up.