Supplementary file 1_Functional family therapy across the COVID-19 pandemic.docx

The present study examines the effectiveness of the Functional Family Therapy (FFT) program in Norway through the COVID-19 pandemic using archival data. Since Norway's national lockdowns imposed significant disruptions on program delivery, concerns arose regarding FFT's effectiveness during the public health emergency; however, this hypothesis remained untested. This exploratory study uses a multigroup quasi-experimental design by comparing clients before and during the COVID-19 pandemic. The data includes 518 adolescents and their families referred to FFT for serious and persistent antisocial behavior. The mean age of the youth was 14.2 years and the representation between boys and girls was close to equal (49.4% girls). Statistical analyses showed that clients' attributes at admission remained stable, and FFT remained effective in bringing about behavioral improvements and risk reductions throughout the pandemic. Additionally, regression results suggested that older clients tended to have greater reductions in behavioral problems and risk levels before lockdowns; however, this age effect disappeared after the onset of COVID. Clients returning home from institutional care reported stronger behavioral gains, whereas those living in foster homes showed less favorable risk outcomes. Collectively, these results suggest that both the FFT target population and treatment outcomes remained stable despite disruptions in program delivery during the pandemic.