Individual Trajectories of Specialist Substance Use Disorder and Mental Health Treatment Utilization Among Young Adults With Substance Use Problems: A Cohort Study.

Objective: The aim of the study was to identify groups of young adults with distinct longitudinal patterns of use of treatment for substance use disorders and mental health (MH) problems and to investigate potential explanatory factors for different patterns of treatment use over time, including sociodemographic factors.

Methods: The sample consisted of 447 young adults aged 16-29 years who entered long-term residential substance use disorder treatment facilities in Norway from 2011 to 2016. In this study, we obtained data collected by the Norwegian Patient Registry and Statistics Norway. These data were linked with the electronic health record data of the substance use disorder treatment facilities from which the participants were recruited. Growth mixture modeling was performed. The identified groups were further compared using analysis of variance or test.

Results: Four groups of participants for total treatment use, substance use disorder treatment use, and MH treatment use were identified. Most participants from the overall sample were classified as members of a group characterized by a low and stable pattern of treatment use over time. A group with a high and stable pattern of treatment use was identified in total and MH treatment use. The proportion of participants with higher levels of substance use disorder treatment use at the end of the study period than at the beginning was larger (35%) than in the case of MH treatment use (14.2%). Younger age was associated with a decreasing pattern of MH treatment use and with an increasing pattern of substance use disorder treatment use over time. There were larger proportions of female participants in groups with a stable high use of MH treatment and in groups with an initially increasing trend of substance use disorder treatment use. Findings revealed that most participants across the identified groups were recipients of welfare benefits, had low educational attainment, and were not working.

Conclusions: Results demonstrated significant variation in trajectories of treatment use among young adults with substance use disorder. Differences in treatment use could indicate differences in symptom severity and complexity. In this study, treatment use was associated with socioeconomic factors, sex, and age. Integrative approaches, including interagency and interdisciplinary collaboration, will often be necessary to sufficiently address the multidimensionality of substance use disorder.