Clinical course and outcomes of Iranian children with juvenile dermatomyositis and polymyositis

This study evaluated the clinical features, course, and outcomes of Iranian children with juvenile dermatomyositis (JDM), juvenile polymyositis (JPM), and other uncommon connective tissue disorders. A chart review of 85 Iranian children with JDM and JPM was performed during a 10-year period from 2003 to 2013. The patients' clinical signs and symptoms, laboratory data, and other factors affecting clinical outcomes were recorded using questionnaires. Statistical analysis was performed using SPSS software version 20. In all, 40 boys and 45 girls were included in the study (F/M, 1.1:1). Disease frequency was significantly higher in boys aged < 5 years (F/M, 0.4:1) and girls aged > 5 years (F/M, 1.6:1). The combined mean age at diagnosis was 7.5 years. Muscle weakness, particularly in the proximal muscles of lower extremities (96 %); fatigue (83 %); and heliotrope rash (71 %) were the most frequently recorded symptoms. Elevated lactate dehydrogenase level was the most common enzyme disturbance (98 %). Monocyclic course was seen in 60 % of patients. The mean treatment duration was 3 years. The incidence rate of complications such as calcinosis, lipodystrophy, and growth disturbances was 20, 9, and 30 %, respectively. The occurrence of these complications in patients with monocyclic disease was significantly lower. Vital organ involvement led to the death of four patients. The incidence of calcinosis was significantly lower in patients having a shorter interval between disease onset and treatment. Two important complications, failure to thrive and lipodystrophy, were significantly higher in patients having antinuclear antibodies. The incidence of the above three complications was higher in patients with polycyclic or continuous chronic disease. Respiratory failure was the most common cause of patient mortality.