Evaluating treatment outcomes across four substance use treatment settings: a 12-month longitudinal study in Iran

Findings indicate domain-specific, within-modality changes rather than comparative effectiveness between settings. In TCs, short-term within-modality declines were observed in alcohol and selected illicit opioids at EOT alongside limited employment opportunities during residence due to programmatic restrictions. Within MMT, improvements were observed in selected psychosocial indicators at follow-up, consistent with stabilization during ongoing care. Within DICs, reductions were observed in health problems and certain risk behaviors, aligning with their harm-reduction and linkage role. Within Article 16, short-term declines were observed in selected substances and health problems during observation; durability after discharge is uncertain without structured aftercare. Overall, no single modality appears universally superior; matching clients to treatment according to target outcomes, and implementing stepped-care or blended pathways with robust post-treatment supports-particularly following compulsory programs-may optimize long-term impact.