Quality of life of children and adolescents from São Paulo: reliability and validity of the Brazilian version of the Pediatric Quality of Life Inventory<sup>TM</sup> version 4.0 Generic Core Scales

To evaluate the reliability and validity of the Brazilian version of the Pediatric Quality of Life Inventory (PedsQL 4.0) Generic Core Scales and measure the quality of life of healthy children and adolescents and patients with rheumatic diseases.We followed the translation methodology proposed by the developer of the original English version of the PedsQL 4.0. The instrument was administered by interviews in two groups: 240 apparently healthy children and adolescents from São Paulo (SP, Brazil) and 105 patients with chronic rheumatic diseases matched by age, as well as their respective parents or caregivers. The parent proxy-report was administered to the children's parents or caregivers separately on the same day.Cronbach's alpha values were between 0.6 and 0.9 for all dimensions, demonstrating adequate internal consistency. Patients with rheumatic diseases reported significantly lower PedsQL scores on all dimensions when compared to the healthy control group (p < 0.0001). Construct validity of the Brazilian Portuguese version of the PedsQL 4.0 was also confirmed. Parent proxy-report of patients with rheumatic diseases highly correlated with child self-report for physical functioning (r = 0.77, p < 0.001) and school functioning (r = 0.73, p < 0.001). Lower correlations were observed for emotional and social functioning (r = 0.40 and 0.59, respectively, p < 0.001).The tool demonstrated reliability, validity, and the administration was fast and easy. Quality of life in patients with rheumatic diseases was significantly lower than in the healthy control group, supporting the necessity of a comprehensive approach to rheumatic disease management, focused on the psychosocial dimensions.