Objective. To compare muscle strength, physical health, and HLA-DRB1 allele carriage frequencies in patients with longstanding juvenile dermatomyositis (DM) with that of controls, and to determine the presence of and risk factors for muscle weakness and magnetic resonance imaging (MRI)-detected muscle damage in juvenile DM patients. Methods. Fifty-nine patients with juvenile DM examined a median of 16.8 years (range 2.0 -38.1 years) after disease onset were compared with 59 age-and sex-matched controls. Muscle strength/endurance was measured by manual muscle testing (MMT) and the Childhood Myositis Assessment Scale (CMAS); health status was measured by the Short Form 36. HLA-DRB1 alleles were determined by sequencing in patients and 898 healthy controls. In patients, disease activity/ damage was measured by the Disease Activity Score (DAS), Myositis Damage Index (MDI), Health Assessment Questionnaire/Childhood Health Assessment Questionnaire, and MRI scans of the thigh muscles. Early disease characteristics were obtained by chart review. Results. Patients had lower muscle strength/endurance (P < 0.001 for both) and physical health (P ‫؍‬ 0.014) and increased HLA-DRB1*0301 (P ‫؍‬ 0.01) and DRB1*1401 (P ‫؍‬ 0.003) compared with controls. In patients, persistent muscle weakness was found in 42% with MMT (score <78) and in 31% with the CMAS (score <48), whereas MRI-detected muscle damage was found in 52%. Muscle weakness and MRI-detected muscle damage were predicted by MDI muscle damage and a high DAS 1 year postdiagnosis. Conclusion. A median of 16.8 years after disease onset, juvenile DM patients were weaker than the controls; muscle weakness/reduced endurance was found in 31-42% of patients and MRI-detected muscular damage was found in 52% of patients. The outcomes were predicted by high disease activity and muscle damage present 1 year postdiagnosis.

JIA had a detrimental effect on physical HRQoL as measured by the PCS of the SF-36. The strongest correlates were physical disability, pain, fatigue, well-being, and receiving disability/social living allowance.

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Objective.To describe the longitudinal health status from childhood to adulthood in patients with juvenile idiopathic arthritis (JIA), compare outcomes after 19 years with those of controls, and identify early predictors of physical functioning, pain, and physical health-related quality of life (HRQOL).Methods.Between 1995–2003, 96 patients with JIA (mean 6.1 ± 4.0 yrs, 67% female) were assessed within 18 months of diagnosis and every 6 months for the next 3 years with measures of JIA disease activity, physical functioning, pain, fatigue, and well-being. They were reassessed a mean of 18.9 ± 1.5 years later (mean age 25.1 ± 4.2 yrs) with measures of physical disability [Health Assessment Questionnaire–Disability Index (HAQ-DI)], pain, fatigue, well-being (visual analog scale), and physical and mental health-related quality of life (HRQOL; Medical Outcomes Study 12-item Short Form Health Survey, version 2).Results.During the first 3 years, physical disability improved (p < 0.001) and the proportion of patients reporting best possible well-being increased (p = 0.013), while pain and fatigue did not change. At 3- and 19-year followups, patients had similar levels of physical disability, well-being, and pain, but fatigue increased (p = 0.016) and the number of patients with HAQ-DI = 0 decreased (p = 0.001). After 19 years, patients had worse pain and physical HRQOL than controls (p < 0.001). Pain, active joints, and physical disability during the first 3 years were associated with more disability and pain and worse physical HRQOL after 19 years (p < 0.001–0.047).Conclusion.Patients with JIA reported similar physical functioning, well-being, and pain at 3- and 19-year followups, but more fatigue after 19 years. Patients also had worse health status than controls after 19 years. Pain, active joints, and physical disability were early predictors of unfavorable outcomes.