The effectiveness of Forensic Outpatient Systemic Therapy in the treatment of juvenile antisocial behavior: A study protocol of a Multiple Case Experimental Design.

Background: Juvenile antisocial behavior can have long-lasting and devastating effects for juveniles themselves, victims, and society. Evidence-based treatment is vital. Forensic Outpatient Systemic Therapy (Forensische Ambulante Systeem Therapie; FAST) is a promising treatment for juveniles showing severe antisocial behavior including aggression, (domestic) violence, and delinquent behavior. FAST has a flexible intensity and length, addresses individual and systemic risk and protective factors, and is responsive to the abilities of the client (system), intervention characteristics all considered crucial for effective treatment. The current study will investigate whether FAST is effective in reducing aggression of the juvenile, reaching client formulated subgoals, and improving family functioning. Processes of change will be examined, as well as mediation by reaching client formulated subgoals and improved family functioning.

Methods: A Multiple Case Experimental Design (MCED) with an ABC design will be performed (A = baseline, B = intervention, and C = follow-up). Juveniles with primary aggression and/or anger problems (N = 15) and their caregiver(s) will be recruited. Data collection will consist of self-report questionnaires and case file analysis. Participants fill out frequent short self-report questionnaires (twice a week during phase A, every other week during phase B, and every week during phase C) and two main questionnaires at the start of the intervention and immediately after intervention end, thereby covering a period of 5 to 11 months. Both visual and statistical analyses will be performed.

Discussion: This study will generate robust knowledge and inform clinical practice on the effectiveness, processes of change, and mediating mechanisms of FAST, aiming to improve the treatment of future families within youth forensic care.

Trial Registration: This trial was registered at ClinicalTrials.gov on 28/08/2023, protocol ID 60-63600-98-1138a.