Page 18 - Age of onset of disruptive behavior of residentially treated adolescents -Sjoukje de Boer

indicated due to the behavior, or when the youngster committed a specific criminal offence (De Boer, Van Oort, Donker, Verheij, & Boon, 2012).
Dropout
While the vast majority of treated individuals are better off than their untreated counterparts (Duncan, Miller, Wampold, & Hubble, 2010; Eyberg et al., 2008), this does of course not mean that treatment aimed at reducing behavioral problems is effective for everyone. However, the effectiveness of interventions aimed at reducing disruptive behavior among children and adolescents is substantial, with effect sizes between .23 and .51 (Bennett & Gibbons, 2000; McCart, Priester, Davies, & Azen, 2006; Serketich & Dumas, 1996). Therefore, it can at least be stated that treatment increases the likelihood that psychiatric and behavioral problems improve (Kazdin, 2016; Kazdin, Mazurick, & Siegel, 1994; M. Shaw et al., 2012). Continued behavioral problems on the other hand, increase the likelihood of leaving school without a qualification, engaging in delinquent activities, abusing drug and alcohol, and adult unemployment. It is therefore imperative to reduce dropout, since psychiatric disorders or behavioral problems are likely to persist or even worsen later in life (De Haan, Boon, De Jong, Hoeve, & Vermeiren, 2013; Moffitt et al., 2002). Assuming that most individuals signing up for treatment, actually are in need of treatment, dropout percentages found in literature are alarmingly high. A meta-analysis showed that among non-residential child and adolescent outpatients dropout percentages ranged from 28 to 75% (De Haan et al., 2013). In a sample similar to the participants in the present thesis, the dropout rate was 59% (Van den Reijen, Nijman, Orobio de Castro, & Schmitz, 2013).
Considering the characteristics of the orthopsychiatric sample we focus on, dropout was expected to be a major issue. Especially since many client characteristics that are associated with dropout prevail in clients with disruptive behavior. In a meta- analysis (De Haan et al., 2013) on dropout in non-residential outpatient settings for instance, several pre-treatment client characteristics have been listed, i.e., the presence of an externalizing disorder, intensity of self reported externalizing and total problems, ethnic minority status, gender (male), lower academic functioning, higher
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