Factorial invariance of child self-report across socioeconomic status groups: a multigroup confirmatory factor...

The measurement of health-related quality of life (HRQOL) in pediatric medicine and health services research has grown significantly over the past decade. Socioeconomic status (SES) differences in health outcomes have been extensively documented in adult and child populations. In order for HRQOL comparisons to be meaningful across different socioeconomic status (SES) groups, items on a HRQOL measure must have equivalent meaning across the SES subpopulations being compared. That is, they must demonstrate factorial invariance. This study examined factorial invariance of child self-report for ages 5-18 across SES groups in 453 children utilizing the PedsQL 4.0 Generic Core Scales. Multigroup Confirmatory Factor Analysis was performed specifying a five-factor model across two SES groups. SES groupings were assigned according to the Hollingshead Index of Social Status. Factorial invariance across socioeconomic status groups was demonstrated based on stability of the Comparative Fit Index (CFI) between the models, and several additional indices of practical fit including the Root Mean Squared Error of Approximation (RMSEA), the Non-Normed Fit Index (NNFI), and the Parsimony Normed Fit Index (PNFI). The findings support an equivalent five-factor structure of child self-report on the PedsQL across the two SES groups studied. Based on these data, it can be concluded that children across SES groups interpreted items on the PedsQL in a similar manner.