Health-related quality of life in children with epilepsy: Development and validation of self-report and parent proxy measures

Purpose: To answer a need to include and measure accurately the impact and burden of epilepsy as outcomes of interventions with affected children, we developed and validated self-report and parent-proxy respondent health-related quality of life (HRQL) instruments for preadolescent children with epilepsy. Methods: We combined qualitative and quantitative research methods. Items were extracted from focus group discussions involving children with epilepsy and their parents. We created scales formatted with alternative paired options of forced responses and used factor analysis to generate relevant subscales and reduce the number of items. We checked internal consistency, assessed test-retest reliability 10-14 days apart, and documented construct validity. Results: A sample of 381 children with epilepsy, age 6-15 years, and their parents independently completed a 67-item questionnaire, from which we chose five items for each subscale. The measures share four subscales, but each measure has an additional distinct subscale. The children and parents could discern differences and report differentially between the various aspects of the HRQL. Internal consistency measured with Cronbach's a was acceptable for all subscales; construct validity has been demonstrated from the testing of several hypotheses. Test-retest reliability examined with the intraclass correlation coefficient was satisfactory for the parents and for children age 8 years and older. The correlations between the mothers' and children's responses was poor to moderate. Conclusions: The data demonstrate sound psychometric properties for both related measures, which are easy to administer for children with epilepsy who are 8 years and older and their parents. The subscales encompass HRQL dimensions judged most important by children with epilepsy for the self-report measure and by parents for the proxy response measure. The parent-proxy measure should be useful as a complement to the child self-report measure in evaluating the validity of parental assessment of the child's health status; in longitudinal outcome research; and in HRQL assessment of children who are unable to respond independently.