Obtaining preference scores for an abbreviated self-completion version of the Teen-Addiction Severity Index (ASC T-ASI) to value therapy outcomes of systemic family interventions: a discrete choice experiment.

Background: Systemic family interventions for adolescents with problems of substance use and/or delinquency are increasingly focused subject of economic evaluations. Treatment effects go beyond improvements in commonly measured health-related quality of life (HRQOL). The Teen-Addiction Severity Index (T-ASI) was identified as capable of capturing these broad outcomes. However, it lacks preference-based scores. An abbreviated self-completion version (ASC T-ASI) was created and validated, covering the T-ASI domains substance use, school, work, family, social relationships, justice, and mental health. This study aimed to obtain societal preference scores for the ASC T-ASI.

Methods: Preferences were elicited in a sample of the Dutch general adult population (n = 1500), using a web-based Discrete Choice Experiment. Choice tasks included two unlabeled alternatives with attributes and levels corresponding to the domains and levels of the ASC T-ASI. A pilot study (n = 106) informed priors, optimal presentation, and number of choice tasks applied in the main study. Data were analyzed using a mixed multinomial logit model.

Results: Preference scores were logically ordered, with lower scores for worse ASC T-ASI states. Scores were most influenced by reductions in problems concerning the domains substance use, mental health, justice, and family. Tariffs were calculated for each ASC T-ASI state, ranging from 0 (worst situation) to 1 (best situation).

Conclusions: The tariffs enable preference-based assessments of the broad effects of systemic family interventions for adolescents with problems of substance use and/or delinquency. The outcome reflects addiction-related rather than health-related utility and can be used next to generic HRQOL instruments in relevant economic evaluations. Given the source used for the preferences, interpretations and valuation of scores require attention.