Use of the child health utility and strengths and difficulties outcome measures in economic evaluations of school-based interventions: data from a cluster-randomised controlled trial in Northern Ireland

Abstract

BackgroundThere is growing evidence linking early social and emotional wellbeing to later academic performance and various health outcomes including mental health. An economic evaluation was designed alongside the Roots of Empathy cluster-randomised trial evaluation, which is a school-based intervention for improving pupils' social and emotional wellbeing. Exploration of the relevance of the Strengths and Difficulties Questionnaire (SDQ) and Child Health Utility 9D (CHU9D) in school-based health economic evaluations is warranted. The SDQ is a behavioural screening questionnaire for 4–17-year-old children, consisting of a total difficulties score, and also prosocial behaviour, which aims to identify positive aspects of behaviour. The CHU9D is a generic preference-based health-related quality of life instrument for 7–17-year-old children. MethodsNon-randomised SDQ (total difficulties and prosocial behaviour scores) and CHU9D utility values were reported with standard descriptive statistics at baseline (n=1179), after intervention completion (n=1181), and 12-month follow-up (n=1277) from intervention completion. Agreement between the measures was based on Spearman's rank correlation coefficient, graphical techniques, and simple calculations. Regression analysis was carried out to assess the effect and variation in SDQ and CHU9D utility values in relation to age, sex, and deprivation. FindingsMean CHU9D utility values were 0·84 (SD 0·11) at baseline, 0·85 (0·11) after intervention completion, and 0·85 (0·10) at 12-month follow-up. Mean SDQ total difficulties scores were 12·11 (3·27), 11·78 (3·14), and 11·95 (3·07), respectively. Mean SDQ prosocial behaviour scores were 8·12 (2·18), 8·42 (2·00), and 8·62 (1·93), respectively. A correlation between total difficulties and utilities at baseline and 12-month follow-up was evident (r=–0·10, p=0·004 and −0·08, p=0·018). No correlation was found after intervention completion or between prosocial behaviour and utilities. Multivariate regression analysis showed that child health utilities were significantly associated with total difficulties score at baseline (β=–0·09, 95% CI −0·03 to −0·16; p=0·007) and after intervention completion (−0·08, −0·01 to −0·15; p=0·016) after adjustment for deprivation. No significant association between utilities and total difficulties was found at 12-month follow-up. However, child health utilities were significantly associated with prosocial behaviour at 12-month follow-up (0·05, 0·01–0·08; p=0·010) after adjustment for age. No significant association between utilities and prosocial behaviour was found at any other timepoints. InterpretationThe SDQ and CHU9D are able to measure outcomes in children aged 8–10 years within an educational setting and there is initial evidence that they are related in their measurement properties. To our knowledge, the SDQ and CHU9D have not yet been used to predict longer-term outcomes within an economic evaluation context. This is an important avenue for further research because issues remain as to whether these childhood measures could be extrapolated into adulthood. A decision analytic model for long-term analysis is now being developed. FundingThis project was funded by the National Institute for Health Research (NIHR) Public Health Research programme.