title: Paving the way for the use of the SDQ in economic evaluations of school-based population health interventions: an empirical analysis of the external validity of SDQ mapping algorithms to the CHU9D in an educational setting.
abstract: OBJECTIVE
  The Strengths and Difficulties Questionnaire (SDQ) is a behavioural screening tool for children. The SDQ is increasingly used as the primary outcome measure in population health interventions involving children, but it is not preference based; therefore, its role in allocative economic evaluation is limited. The Child Health Utility 9D (CHU9D) is a generic preference-based health-related quality of-life measure. This study investigates the applicability of the SDQ outcome measure for use in economic evaluations and examines its relationship with the CHU9D by testing previously published mapping algorithms. The aim of the paper is to explore the feasibility of using the SDQ within economic evaluations of school-based population health interventions.
  
  
  METHODS
  Data were available from children participating in a cluster randomised controlled trial of the school-based roots of empathy programme in Northern Ireland. Utility was calculated using the original and alternative CHU9D tariffs along with two SDQ mapping algorithms. t tests were performed for pairwise differences in utility values from the preference-based tariffs and mapping algorithms.
  
  
  RESULTS
  Mean (standard deviation) SDQ total difficulties and prosocial scores were 12 (3.2) and 8.3 (2.1). Utility values obtained from the original tariff, alternative tariff, and mapping algorithms using five and three SDQ subscales were 0.84 (0.11), 0.80 (0.13), 0.84 (0.05), and 0.83 (0.04), respectively. Each method for calculating utility produced statistically significantly different values except the original tariff and five SDQ subscale algorithm.
  
  
  CONCLUSIONS
  Initial evidence suggests the SDQ and CHU9D are related in some of their measurement properties. The mapping algorithm using five SDQ subscales was found to be optimal in predicting mean child health utility. Future research valuing changes in the SDQ scores would contribute to this research.
authors.affiliation: Health Economics and Health Technology Assessment, Institute of Health and Wellbeing, University of Glasgow, 1 Lilybank Gardens, Glasgow, G12 8RZ, UK. nicki.boyer@glasgow.ac.uk.
authors.forename: Nicole R S
authors.identifier: http://orcid.org/0000-0003-3371-917X
authors.initials: NR
authors.lastname: Boyer
authors.affiliation: Centre for Effective Education, School of Education, Queen's University Belfast, Belfast, BT7 1LN, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Miller
authors.affiliation: Centre for Effective Education, School of Education, Queen's University Belfast, Belfast, BT7 1LN, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Connolly
authors.affiliation: Health Economics and Health Technology Assessment, Institute of Health and Wellbeing, University of Glasgow, 1 Lilybank Gardens, Glasgow, G12 8RZ, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: McIntosh
mesh_terms: D000293:Adolescent; D000465:Algorithms; D000067289:Behavior Observation Techniques; D002648:Child; D000067576:Child Health; D002675:Child, Preschool; D003362:Cost-Benefit Analysis; D005260:Female; D006801:Humans; D008297:Male; D009660:Northern Ireland; D017063:Outcome Assessment, Health Care; D011788:Quality of Life / Q000523:psychology*; D000070777:School Teachers; D012574:Schools; D011795:Surveys and Questionnaires
keywords: CHU9D; Child health utility; Health outcomes; Population health; SDQ; School-based intervention