A scoping review of the global evolution of addiction treatment systems: evidence-based models and implementation challenges for health system adaptation in Iran.

Addiction treatment systems have increasingly evolved from fragmented and isolated models of care toward integrated, continuous, and community-oriented approaches. However, evidence regarding their global evolution, emerging service models, and adaptation challenges across different health-system contexts remains dispersed. This scoping review explored the development of addiction treatment systems, identified evidence-based service models and their implementation challenges, and explore their implications for health-system adaptation in Iran. The review followed the Joanna Briggs Institute (JBI) framework and PRISMA-ScR guidance, with searches conducted in PubMed, Scopus, and Web of Science databases for studies published between 2010 and 2026 in English. Among 30,773 identified records, 23,655 duplicates were removed, leaving 7118 records for screening. After full-text assessment, 107 sources of evidence were included in the synthesis. The results identified six key themes shaping the evolution of addiction treatment systems: integration of addiction treatment into primary health care; concurrent management of substance use and psychiatric disorders; digital health and technological innovation; family and community engagement; organisational capacity, governance, and quality improvement; and equitable access to care for vulnerable populations. The main challenges were related to workforce capacity, financing, and coordination between services. In Iran, improving integration and strengthening system capacity may support more accessible addiction care.