Page 101 - Age of onset of disruptive behavior of residentially treated adolescents -Sjoukje de Boer

therapist involved also inquired about this information with the participant, his parents
and the referring professional (e.g., guardian or probation officer) during the intake procedure. The disruptive behavior of the participants was categorized according to
the framework of Frick and colleagues (Frick et al., 1993), and included aggression (i.e., homicide attempt, assault, robbery, physical abuse, sexual offences, threatening someone), oppositional behavior (i.e., disobedient, doing things their own way, stubbornness), status offences (i.e., running away, truancy, substance usage), and property violations (i.e., selling drugs, lying, possession of weapons, stealing, setting
fires, vandalism, fencing stolen goods, traffic offences). 6
For each participant the presence and age of onset of disruptive behavior had been determined. Disruptive behavior was considered present when it was mentioned by at least one of the sources (i.e., file, therapist or patient). When no information was available, it was coded as unclear (or missing, depending on the reason for unavailability). Participants with disruptive behavior starting prior to age 12 were considered belonging to the EO group and those whose disruptive behavior started from age 12 as being part of the AO group (De Boer et al., 2013; De Boer et al., 2012; De Boer et al., 2007). The distinction in the early-onset (EO) and adolescent-onset (AO) groups was made by the main researchers and was done independently from the data collection. The interrater reliability (Cohen’s Kappa .79) had been determined based on independent ratings by two researchers on a random subset of the sample (De Boer et al., 2012).
Cannabis usage prior to the admission
Data with regard to cannabis usage prior to the admission was collected by research assistants and was based on patient interview and file review. The age at which cannabis was used for the first time as well as the frequency of use was queried. The therapist involved also inquired about this information with the participant, his parents and the referring professional (e.g., guardian or probation officer) during the intake procedure.
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