Objective. To examine the validity of the Childhood Health Assessment Questionnaire (CHAQ) in patients with juvenile idiopathic inflammatory myopathy (IIM).Methods. One hundred fifteen patients were enrolled in a multicenter collaborative study, during which subjects were assessed twice, 7-9 months apart. Physical function was measured using the CHAQ. Internal reliability was assessed using adjusted item-total correlations and item endorsement rates. Construct validity was assessed by comparing predicted and actual correlations of the CHAQ with other measures of physical function and disease activity. Responsiveness was assessed by calculating effect size (ES) and standardized response mean (SRM) in a group of a priori defined "improvers."Results. Item-total correlations were high (r(s) range = 0.35-0.81), suggesting all items were related to overall physical function. Manual muscle testing and the Childhood Myositis Assessment Scale correlated moderate to strongly with the CHAQ (r(s) = -0.64 and -0.75. both p < 0.001). Moderate correlations were also seen with the physician global assessment of disease activity (r(s) = 0.58, p < 0.001). parent global assessment of overall health (r(s) = -0.65, p < 0.001). Steinbrocker function class (r(s) = 0.69, p < 0.001), and global skin activity (r(s) = 0.40, p < 0.001), while global disease damage and skin damage had low correlations (r(s) = 0.13 and 0.07, p 0.17). Responsiveness of the CHAQ was high. with ES = 1.05 and SRM = 1.20.Conclusion. In this large cohort of patients with juvenile IIM, the CHAQ exhibited internal reliability, construct validity and strong responsiveness. We conclude that the CHAQ is a valid measure of physical function in juvenile IIm, appropriate for use in therapeutic trials, and potentially in the clinical carl of these patients.

Objective, To describe the patient population referred to pediatric rheumatology centers (PRC) across the US 1992-95; and to compare these results to data on regional PRC populations. Methods, A Pediatric Rheumatology Disease Registry was established in 1992, Data on new patients seen at 25 PRC across the US were submitted to the registry for a 36 month period from 1992 through 1995. Results. A total of 12,939 patients were submitted to the registry. Of these patients, 5245 (40.5%) had rheumatological diagnoses, Patients with juvenile rheumatoid arthritis were the largest group of the patient population (2071 patients - 16% of total diagnoses), There were 1568 patients with other forms of childhood arthritis (12%), 1172 with collagen vascular diseases (9%), and 434 with vasculitis (3.3%). Over 50% of the patients had nonrheumatologic diagnoses, including 1577 with idiopathic pain syndromes (12%). Other diagnoses included infections, orthopedic conditions, and malignancies. Fourteen percent of the patients were not given a diagnosis at the time of the initial visit. Conclusion, PRC see a wide variety of patients. Although the majority do have rheumatologic conditions, over 50% of new patients have conditions not autoimmune in origin. Fourteen percent of the patients cannot be diagnosed at the time of their first clinic visit, requiring time to see the evolution of their symptoms before a definitive diagnosis can be assigned.