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

Abstract

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.

Keywords: JIA; Parent global assessment; health-related quality of life.

Fig. 1

Violin box plots for parent global and HRQoL measures at enrolment (A), 6 months (B) Parent global, quality of my life health scale (HRQoML), and juvenile arthritis quality of my life questionnaire (JAQQ) scores were multiplied by 10. Range of scores are 0 (best) to 100 (worst) for parent global, 0 (worst) to 100 (best) for HRQoML, 10 (best) to 70 (worst) for JAQQ, 0 (worst) to 100 (best) for child health questionnaire (CHQ) and 50 is the mean of healthy children, 0 (worst) to 100 (best) for paediatric quality of life inventory (PedsQL). Phys: Physical; Psych: Psychosocial.

Fig. 2

Construct validity of the parent global as a measure of health-related quality of life Spearman correlations (95% confidence intervals) of parent global with measures of heath related quality of life at diagnosis (A), at 6 months (B); correlations with other related JIA measures at diagnosis (C), at 6 months (D). Pain was measured on 10-cm visual analogue scale. CHAQ: childhood HAQ disability index; CHQ: child health questionnaire; HRQoML: quality of my life health scale; JAQQ: juvenile arthritis quality of life questionnaire; Joints: active joint count; PedsQL: paediatric quality of life inventory; PGADA: physician’s global assessment of disease activity.

Fig. 3

Path analysis for parent global at diagnosis (A), 3–9 months after diagnosis (B) Structural equation modelling results after substituting parent global in models previously reported for HRQoML [35]. See Supplementary Data S1, available at Rheumatology online for details. At diagnosis: ≤28 days after actual diagnosis date; 3–9 months: 3–9 months after actual diagnosis date; dashed lines: paths not supported; numbers: path coefficients; colour shades: light, path coefficients <0.2; medium, 0.2–0.49; dark, ≥0.5; medication score: weighted sum of potency of treatments; mode of administration: 1, oral to 4, repeated intravenous injection; joints: active joint count; PGADA: physician’s global assessment of disease activity; CHAQ DI: childhood HAQ disability index.