Parent-Proxy EQ-5D Ratings of Children with Attention-Deficit Hyperactivity Disorder in the US and the UK

Background: The symptoms of attention-deficit hyperactivity disorder (ADHD) are associated with impairment in multiple domains of health-related quality of life (HR-QOL). HR-QOL of children with ADHD has been assessed by relatively long multidimensional questionnaires. A review of the literature found no studies using the brief, well established EuroQoL Five-Dimension Questionnaire (EQ-5D) to estimate the HR-QOL of children with ADHD. The objective of this study was to assess the HR-QOL of children with ADHD using parents' responses to the proxy version of the EQ-5D. Methods: Participants were recruited in the midwestern US and in the vicinity of London, England. All parents completed three questionnaires: the EQ-5D proxy version; a measure of ADHD symptoms based on Diagnostic and Statistical Manual of Mental Disorders (4th Edition) [DSM-IV] criteria (the Attention-Deficit/Hyperactivity Disorder Rating Scale-IV - Parent Version [ADHD-RS]); and either the Child Health Questionnaire - Parent Form 50 (CHQ-PF50) or the Child Health and Illness Profile - Child Edition (CHIP-CE), which are both generic multidimensional paediatric HR-QOL questionnaires. Results: A total of 126 parents of children with ADHD participated in the study: 43 in the US and 83 in the UK. On the EQ-5D, participants indicated that 78.6% of their children experienced some problems or extreme problems performing usual activities, while 64.8% believed their child demonstrated some or extreme anxiety or depression. The mean EQ-5D index score was 0.75 and the mean visual analogue scale (VAS) score was 73.9. The EQ-5D index and VAS scores were found to be significantly correlated (p < 0.05) with several domains of the CHQ-PF50 (e.g. Mental Health, Self-Esteem, Family Activities, Psychosocial Summary Score) and the CHIP-CE (e.g. Satisfaction, Comfort, Academic Performance, Peer Relations). The EQ-5D scales were also significantly correlated with the ADHD-RS scales (p < 0.001). Conclusion: The proxy version of the EQ-5D, completed by parents, was able to detect impairment in children diagnosed with ADHD in the US and the UK. Furthermore, the EQ-5D index and VAS scores demonstrated construct validity among this sample through significant correlations with an ADHD symptom measure and previously validated multidimensional QOL instruments. These results suggest that parent-proxy EQ-5D ratings are feasible and valid for use as part of an overall health outcomes assessment in clinical studies of childhood ADHD.