We need accurate screening measures for attention-deficit/hyperactivity disorder (ADHD) to ensure that children with the disorder are referred for assessment without raising concern for children with normal behaviour. The Strengths and Difficulties Questionnaire (SDQ) provides hyperactivity-inattention (HI), conduct, emotional and peer problem subscales and impact scores that may be used for screening. The aim of the study was to investigate the predictive validity of the Danish version of the parent SDQ HI subscale at the child age of 7 years for subsequent clinically diagnosed ADHD (age 8-15 years). Participants were part of the Danish National Birth Cohort (N = 51,096), and children with ADHD were identified through the Danish National Health registries (n = 943). Receiver operating characteristic analysis showed that the screening accuracy for the HI scores was good (area under the curve = .84). With Cox multivariate regression analysis, we found that SDQ HI subscale scores ≥ 7 with impact gave a nearly 14-fold [hazard ratio (HR) = 13.59] increased risk for ADHD, while conduct and emotional problems indicated low risk (HRs of 1.62 and 1.67, respectively). For the HI subscale to be a sensitive measure for ADHD, a low cutoff (4) was needed, but gave many false screening positives (PPV = .02). Although the diagnostic accuracy of the parent version of the SDQ HI subscale for predicting ADHD was good, our results question the feasibility of screening the general child population for ADHD with only the parent SDQ HI subscale.
Keywords: ADHD; Cohort study; Patient registries; SDQ.