Age-of-onset classification of conduct disorder: reliability and validity in a prospective cohort study.
OBJECTIVE
To test in a prospective clinical cohort study the reliability and validity of the age-of-onset subtyping of conduct disorder.


METHODS
Participants were adolescents referred to psychiatric clinics who met DSM-III-R criteria for conduct disorder by structured diagnostic interview. Age of onset was the reported age of the first conduct disorder symptom. The reliability of age-of-onset report was tested by assessing agreement within informant on interviews 2 to 4 weeks apart. Age-of-onset groups were compared within informant on rates of correlates and symptom and social functioning outcomes over a period of 3 years.


RESULTS
The reliability of age-of-onset report was low (kappa of 0.1 and 0.4 by adolescent and parent informant, respectively). Although the early-onset group had elevated rates of attention-deficit/hyperactivity disorder, family disadvantage, and aggressive and nonaggressive antisocial behaviors at inclusion, growth curve analysis showed that age-of-onset subtyping had no predictive validity.


CONCLUSIONS
The reliability of ascertainment of age of onset of antisocial behavior requires further study. While age-of-onset subtyping has heuristic value with respect to the study of the causal pathways to conduct disorder, it is premature to use this system in clinic settings.
Sanford
M
M
Department of Psychiatry, McMaster University, Hamilton, Ontario, Canada.
Boyle
M H
MH
Szatmari
P
P
Offord
D R
DR
Jamieson
E
E
Spinner
M
M
D000293:Adolescent; D017668:Age of Onset; D000704:Analysis of Variance; D019955:Conduct Disorder / Q000145:classification* / Q000175:diagnosis* / Q000453:epidemiology; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D009864:Ontario / Q000453:epidemiology; D011446:Prospective Studies; D011594:Psychometrics; D015203:Reproducibility of Results