Measurement invariance of the Pediatric Quality of life index in a child and adolescent mental health population.

PURPOSE: To evaluate the measurement invariance of the Pediatric Quality of Life Index (PedsQL) in a population of children and adolescents participating in mental health treatment.

METHODS

We analyzed PedsQL data from three child and adolescent mental health service (CAMHS) services (walk-in, day hospital, intensive community treatment). We fit ordered-categorical confirmatory factor analysis (CFA) to the canonical four-domain model and a theory-refined variant with targeted cross-loadings. We then examined multi-group measurement invariance (configural, metric, scalar) across service streams, diagnosis, gender, race/ethnicity (White vs. racialised).) Finally, we assessed item-level bias (i.e., differential item functioning; DIF) with an ordinal logistic approach using an observed-score nested model sequence.

RESULTS

For the CFA, we found that the four-domain structure fit well and that allowing two theory-guided cross-loadings-Physical items 7 and 8 onto the Emotional domain yielded a strong fit. We found full scalar invariance across all groups tested. For DIF testing, no items exhibited meaningful uniform or non-uniform DIF.

CONCLUSIONS

PedsQL domain scores demonstrate evidence of structural validity and preliminary evidence of measurement invariance across the CAMHS subgroups evaluated. This provides support for the use of PedsQL scores in CAMHS.