Studying the epidemiology of attention-deficit hyperactivity disorder: screening method and pilot results

As part of a larger epidemiologic study of risk factors for attention-deficit hyperactivity disorder (ADHD), this pilot study combined parent and teacher information to estimate ADHD prevalence among elementary school children in a North Carolina county. The methods developed for this study and the pitfalls we encountered illustrate the challenges involved in conducting population-based studies of ADHD.

We employed 2-stage screening using DSM-IV criteria. Teachers completed behaviour-rating scales for all children. We then administered a structured telephone interview to parents of potential cases. We screened 362 of 424 (85%) children in grades 1 to 5 in 4 schools.

According to parent reports, 43 children (12%) had previously been diagnosed with ADHD by a health professional. Thirty-four children (9%) were taking ADHD medication. Forty-six children (12.7%) met study case criteria for ADHD, based on combined teacher and parent reports. Of the 46 cases, 18 (39%) had not been previously identified. Eight previously diagnosed children, however, did not meet case criteria. After we adjusted for nonresponse, the estimated prevalence was 16% (95%CI, 12% to 20%).

These data suggest that the DSM-IV prevalence of ADHD has been substantially underestimated, although the true prevalence in this population may be less than the 16% estimated here. Population-based studies of ADHD are feasible and may provide important information about practice and treatment patterns in community settings, as well as a broader understanding of the etiology and life course of this common disorder.