Validation of the parent global assessment as a health-related quality of life measure in juvenile idiopathic arthritis: results from ReACCh-Out

OBJECTIVES: To (i) validate the JIA parent global assessment (parent global) as a health-related quality of life (HRQoL) instrument; (ii) evaluate measurement properties of accepted HRQoL measures relative to those of the parent global; and (iii) assess causal pathways determining parent global scores. METHODS: Data from the Research in Arthritis in Canadian Children emphasizing outcomes (ReACCh-Out) cohort were used. Measurement properties were assessed in 344 patients at enrolment and 6 months later. Causal pathways were tested by structural equation modelling to understand root causes and mediators leading to parent global scores. RESULTS: Construct validity was supported by Spearman correlations of 0.53-0.70 for the parent global with the Juvenile Arthritis Quality of Life Questionnaire, Quality of My Life health scale (HRQoML), Pediatric Quality of Life Inventory (PedsQL)-Parent, and Child Health Questionnaire (CHQ)-Physical. Exceptions were PedsQL-Child (0.44) and CHQ-Psychosocial (0.31). Correlations were lower (0.14-0.49) with disease activity measures (physician global assessment of disease activity, active joint count, ESR). Responsiveness of the parent global to improvement according to parent ratings (0.51) was acceptable and within the range (0.32-0.71) of that of other measures. Reliability estimates and measurement errors for all measures were unsatisfactory, likely due to the prolonged time between assessments. Causal pathways for the parent global matched those previously reported for HRQoML. CONCLUSIONS: Our results offer support for the parent global as a valid measure of HRQoL for JIA. If confirmed, existing studies using the parent global may be re-interpreted, enhancing our knowledge of HRQoL in children with JIA.