The construct validity of the Child Health Utility 9D-DK instrument.

<bold>Background: </bold>Relative to their application with adults there is currently little information about the application of preference-based health-related quality of life (HRQL) instruments among populations of young people. The Child Health Utility 9D (CHU9D) is a paediatric-specific generic preference-based HRQL instrument, recently translated and linguistically validated into Danish (CHU9D-DK). The purpose of this study was to investigate the construct validity of the CHU9D-DK in a sample of Danish high school students.<bold>Methods: </bold>All students attending a Danish High School were invited to participate in a web-based survey in January 2018 (N = 272). The survey included the CHU9D-DK, the young adult version of the Pediatric Quality of Life Inventory™ 4.0 Generic Core Scales (PedsQL), self-reported health status, presence/absence of disability/chronic diseases, life satisfaction, and socio-economic questions. CHU9D-DK utility scores were generated by employing the two scoring algorithms developed from adults in the UK and adolescents in Australia, respectively. Internal consistency, reliability and construct validity of the CHU9D-DK instrument were investigated.<bold>Results: </bold>Two hundred and twenty-eight (84%) students consented to participate and completed the survey. The mean ± (standard deviation) values of the CHU9D-DK utilities were 0.84 (0.11) when the UK adult algorithm was applied and 0.70 (0.22), when the Australian adolescent algorithm was applied. The mean PedsQL score was 82.32 (13.14). The CHU9D-DK showed good internal consistency reliability (Cronbach's alpha = 0.803). Higher levels of health status and life satisfaction were significantly associated with higher CHU9D-DK utility scores regardless of which scoring algorithm was applied (p-values < 0.001). Students living with a disability/chronic disease exhibited significantly lower utility scores relative to their healthy peers (p-values < 0.05). Higher socio-economic status (approximated by financial situation and frequency of family vacations) was also associated with higher utility scores (p-values < 0.005).<bold>Conclusion: </bold>The CHU9D-DK demonstrated good psychometric performance overall and shows potential as a valid and reliable instrument for assessing the HRQL of Danish young people.<bold>Trial Registration: </bold>ClinicalTrials.gov identifier: NCT03391999, Registered 15 October 2017. [ABSTRACT FROM AUTHOR]