Table 2 shows mean levels of ODD symptoms were similar in youth with ODD only and combined ODD+CD, and mean levels of CD symptoms (total and split into aggressive and non-aggressive symptoms) differed little between cases with CD only and the combined pattern. As Table 2 also makes clear, however, youth who only ever met full diagnostic criteria for one disorder (ODD or CD) during the study period nonetheless typically showed elevated levels of sub-threshold symptomatology for the other disorder. We used the retrospectively reported age at first CD symptom to classify CD cases into childhood and adolescent onset sub-types. Onset of first CD symptom was prior to age 10 for 86.3% of CD diagnoses (childhood onset CD) with the remaining 13.7% classified as adolescent onset CD according to DSM-IV. The mix of child and adolescent onset CD in the CD only (16.4%) and CD+ODD (10.5%) groups did not differ significantly (p=.572).
