Background: The goal of this study was to compare the predictive validity of the two main diagnostic schemata for childhood hyperactivity – attention-deficit hyperactivity disorder (ADHD; Diagnostic and Statistical Manual– IV) and hyperkinetic disorder (HKD; International Classification of Diseases– 10th Edition).
Methods: Diagnostic criteria for ADHD and HKD were used to classify 419 children ages 6 to 16 years referred to a clinic for behavioral problems into one of four groups: HKD, ADHD combined subtype (ADHD-C), ADHD hyperactive-impulsive subtype (ADHD-HI), ADHD inattentive subtype (ADHD-IA). These groups were compared on clinical characteristics including total symptom severity, overall impairment, exposure to psychosocial and neuro-developmental risks, family history of ADHD in first-degree family members, rate and type of comorbidity, intelligence, academic achievement, and on laboratory tests of motor response inhibition and working memory with each other and with normal controls (47).
Results: Of the 419 cases, there were 46 HKD (11.0%), 200 ADHD-C (47.7%), 60 ADHD-HI (14.3%) and 113 ADHD-IA (27.0%) cases. The HKD group had more symptoms and was more impaired on teachers’ ratings than were the other groups. The ADHD-C and HKD groups had poorer inhibitory control than the ADHD-IA, ADHD-HI and control groups, and all four clinic groups showed inhibition deficit compared to controls. Groups did not differ in working memory. Compared to controls, the HKD, ADHD-C, ADHD-HI and ADHD-IA groups had higher familial risk of ADHD, greater psychosocial risk exposure, lower intellectual level and poorer academic attainment. However, we observed no differences among the clinic groups in these characteristics.
Conclusions: Like earlier versions, ICD-10 and DSM-IV continue to delineate diagnostic entities with substantially different prevalence in clinic samples. However, HKD, ADHD-C, ADHD-IA and ADHD-HI groups overlap substantially in terms of important clinical characteristics, although HKD and ADHD-C may be somewhat more severe variants of the condition than ADHD-IA and ADHD-HI.