Page 63 - Age of onset of disruptive behavior of residentially treated adolescents -Sjoukje de Boer

Therapist questionnaire
To assess relevant patient variables (e.g., substance use, criminal offending), therapists filled out a questionnaire based on information they gathered directly from the patients, parents and the referring professional (e.g., guardian or probation officer) during the intake procedure.
At discharge, therapists indicated how the treatment was terminated: (a) 4 termination recommended or supported by the therapist, (b) patient was expelled, (c) treatment was aborted by the patient (e.g., ran away), or (d) another reason (e.g.,
patient was arrested, deceased).
Distinction in the onset of disruptive behavior
Presence of disruptive behavior during childhood was determined based on the age when treatment was sought for disruptive behavior, or when special education was indicated due to this behavior, and the age at which the youngster started to commit criminal offences. The disruptive behavior was categorized according to the framework of Frick and colleagues (Frick et al., 1993), and included aggression (e.g., physical abuse, sexual offences), oppositional behavior (e.g., disobedient), status offences (e.g., truancy, substance abuse), and property violations (e.g., stealing, vandalism) (De Boer et al., 2013; De Boer et al., 2012; Frick et al., 1993). The main researchers made the distinction in the EO and AO groups. For each patient the presence and age of onset of disruptive behavior were determined based on information from file and the interview. Disruptive behavior was considered present when it was mentioned by at least one of the sources. When no information was available, it was coded as unclear (or missing, depending on the reason for unavailability).
The earliest age reported by any source was used as the age of onset. Subsequently, patients with disruptive behavior starting prior to age 12 were considered belonging to the EO group, and those whose disruptive behavior started from age 12 on were considered belonging to the AO group (De Boer et al., 2013; De Boer et al., 2012; De Boer et al., 2007). Using age 12 as the cut-off was in accordance with Moffitt (Moffitt, 1993; Moffitt et al., 1996) and with Dean, Brame and Piquero (1996), who found that differences between the EO and AO groups were only evident
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