The Strengths And Difficulties Questionnaire (SDQ) as a dimensional measure of child mental health

Objective: To provide the first explicit evaluation of the dimensionality of the total difficulties score of the Strengths and Difficulties Questionnaire (SDQ), a widely used measure of child mental health. We do so by validating the SDQ across its full range against the prevalence of clinical disorder. Method: We use two large (N=18,415), nationally-representative surveys of children and adolescents aged 5-16 in the general British population. SDQs were completed separately by parents, teachers and children aged 11-16, and children also received a multi-informant clinician-rated clinical diagnosis. 7,912 children from the baseline survey were also re-assessed for clinical diagnosis at three-year follow-up. Results: Across the full range of the parent, teacher and child SDQ, children with higher total difficulty scores have greater psychopathology as judged by the prevalence of clinical disorder. This was true cross-sectionally and also in predicting to disorder-status three years later. There was no evidence of threshold effects for the SDQ at either high or low scores, but rather the odds of disorder increased at a constant rate across the range (odds ratios between 1.14 and 1.28 per one-point increase in SDQ score). Conclusion: Our findings support the use of the SDQ as a genuinely dimensional measure of child mental health.