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

Purpose
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.
Conclusion
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.

The Strengths and Difficulties Questionnaire overseas: Evaluations and applications of the SDQ beyond Europe

Background During the few years that have passed since it became available, the Strengths and Difficulties Questionnaire (SDQ) has been extensively evaluated and widely applied to assess behaviour disorders of children and adolescents in European countries. In contrast, relatively few reports have published SDQ results obtained in other parts of the world, although its briefness and availability in over 40 languages make this instrument particularly attractive for international collaborations and cross-cultural comparisons concerning clinical and epidemiological issues. Objectives This initial overview summarises some of these non-European experiences with the SDQ by presenting a selection of projects that have either psychometrically evaluated this novel questionnaire, applied it to screen for behaviour disorders, or employed its parent-, teacher- or self-rated versions as research tools. Since a large part of the mentioned studies are ongoing or have only recently been completed, much of the work reported here is still unpublished. Conclusions Across a huge variety of cultures and languages, experience gained with the SDQ in other continents has supported European evidence of good psychometric properties and clinical utility of this questionnaire. Since worldwide usage of the SDQ can be expected to increase in the future, more international coordination is encouraged, in order to fully exploit the promising potentials of this versatile assessment tool and systematically investigate cross-cultural differences and similarities in child and adolescent behaviour.

Assessing childhood difficulties: Comparing the SDQ and the BASC-2

This study of the Behavior Assessment System for Children, Second Edition (BASC-2), had two objectives. First, was to compare the Strengths and Difficulties Questionnaire (SDQ) and the BASC-2. Participants were students from SBISD, identified as having difficulties, assessed with the BASC-2 and completed the SDQ. Based on the small sample (N=8), scores from the SDQ and the BASC-2 were found to correlate highly with one another on most conceptually similar scales. With both Parent and Teacher raters, diagnostic concordance was high for nearly all behavior and emotional problem scales. While the diagnostic concordance of the SDQ and BASC-2 looks promising, results need to be replicated with a larger sample. ^ The second objective was to assess the BASC-2 inter-informant concordance (parent, teacher and child). Participants were 145 students, 3-17 years, 78.6% male, 28% Hispanic, 37% White, 34% Black, and 64% were economically disadvantaged. Of the four dyads, teacher-teacher pairs had the highest correlations and agreement levels, especially on externalizing scale items, regardless of the subjects' age group, gender or ethnicity. ^ Overall, parent-teacher pairs had low to moderate concordance for most scale items, with slightly higher agreement for externalizing problems, with better concordance for preschool children, very low correlations with girls' ratings, but moderate correlations with boy ratings. Correlational results were generally moderate for teachers and parents of White children and low for teachers and parents of Hispanic and Black children. ^ Parent-child self-reports had low concordance for nearly all scale items evaluated, particularly with girl self-raters, but moderate with the boys. Conversely, Teacher-Girl pairs had larger correlations than with Boy. Parents reported substantially higher frequency of disorder endorsement than reported by the children, regardless of the child's ethnicity or gender. While generally low, Teachers and Black students had higher concordance on internalizing measures than Hispanic or White students. Parents of Black students had higher frequency of disorder endorsements than other ethnicities. ^ The difference in format and lack of externalizing measures on the self-report version (SRP) hinders inter-rater comparisons. Future studies using the revised, BASC-2 with children in a school-based setting are needed to assess further its rater reliability. ^

Psychometric behaviour of the strengths and difficulties questionnaire (SDQ) in the Spanish national health survey 2006

Background: The Strengths and Difficulties Questionnaire (SDQ) is a tool to measure the risk for mental disorders in children. The aim of this study is to describe the diagnostic efficiency and internal structure of the SDQ in the sample of children studied in the Spanish National Health Survey 2006. Methods: A representative sample of 6,773 children aged 4 to 15 years was studied. The data were obtained using the Minors Questionnaire in the Spanish National Health Survey 2006. The ROC curve was constructed and calculations made of the area under the curve, sensitivity, specificity and the Youden J indices. The factorial structure was studied using models of exploratory factorial analysis (EFA) and confirmatory factorial analysis (CFA). Results: The prevalence of behavioural disorders varied between 0.47% and 1.18% according to the requisites of the diagnostic definition. The area under the ROC curve varied from 0.84 to 0.91 according to the diagnosis. Factor models were cross-validated by means of two different random subsamples for EFA and CFA. An EFA suggested a three correlated factor model. CFA confirmed this model. A five-factor model according to EFA and the theoretical five-factor model described in the bibliography were also confirmed. The reliabilities of the factors of the different models were acceptable (>0.70, except for one factor with reliability 0.62). Conclusions: The diagnostic behaviour of the SDQ in the Spanish population is within the working limits described in other countries. According to the results obtained in this study, the diagnostic efficiency of the questionnaire is adequate to identify probable cases of psychiatric disorders in low prevalence populations. Regarding the factorial structure we found that both the five and the three factor models fit the data with acceptable goodness of fit indexes, the latter including an externalization and internalization dimension and perhaps a meaningful positive social dimension. Accordingly, we recommend studying whether these differences depend on sociocultural factors or are, in fact, due to methodological questions.