Comparison of the predictive validity of hyperkinetic disorder and attention deficit hyperactivity disorder.

INTRODUCTION: We compared the predictive validity of attention deficit hyperactivity disorder (ADHD; Diagnostic and Statistical Manual - IV Edition) and hyperkinetic disorder (HKD; International Classification of Diseases - 10th Edition) while controlling for the presence of comorbid psychopathology.
METHOD: ADHD and HKD criteria were used to classify 804 clinic-referred children ages 6 to 16 years into one of four non-overlapping groups: HKD, ADHD combined subtype (ADHD-C), ADHD hyper-active-impulsive subtype (ADHD-HI), ADHD inattentive subtype (ADHD-IA). Groups were compared with each other and with normal controls (67) while controlling for age and intelligence on a range of criteria both before and after excluding cases with comorbidity.
RESULTS: Of the 804 clinic participants, 72 (8.9 %) met criteria for ICD-10 HKD, 353 (43.9 %) for ADHD-C, 142 (17.7 %) for ADHD-HI and 237 (29.5 %) for ADHD-IA. There were no differences among the four clinic groups in rate of comorbidity, neuro-developmental or psychosocial risk indices, inter-parental or parent-child discord, family history of ADHD, working memory, and academic or intelligence test scores, but all clinic groups differed from normal controls. By contrast, total number of symptoms, teacher-rated impairment and inhibitory control deficit were greatest in HKD and least in ADHD-C, ADHD-HI, ADHD-IA in that order. Results of the comparisons were essentially unchanged after excluding cases (75%) with a comorbid condition.
CONCLUSIONS: HKD, ADHD-C, ADHD-HI and ADHD-IA had approximately equivalent predictive validity even when comorbidity was taken into account.