Samaneh Ahmadian-Moghadam - Dept. of Addiction Studies, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
Ali Mazyaki - Dept. of Economics, Allameh Tabataba’i University, Tehran, Iran
Emran M Razaghi - Dept. of Psychiatry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran

Background and Objective: Traditional economic studies on substance use disorder treatment have generally focused on the standard evaluation of the costs and benefits of treatment programs.  Meanwhile, willingness to pay (WTP) as a subjective economic indicator uncovers the intangible benefits of treatment that are not gauged by traditional measurements. This study aimed to examine the effect of cost payers’ income and substance use disorder severity on WTP for treatment. Materials and Methods: In an applied descriptive-correlational study, the Addiction Severity Index was used for patients with substance use disorder in two treatment settings: methadone maintenance treatment (MMT) and abstinence-based residential facilities (RFs). The cost payers’ WTP was measured by the contingency valuation method. The cost payers' income and the patients' addiction severity indexes were analyzed in relation to WTP in a regression model. We also used Kruskal-Wallis and Mann-Whitney U statistical tests to examine the differences in the two treatment settings. Results: In MMT clinics, WTP increased with higher income and a higher substance use index, respectively. WTP decreased with the worse grades in the patients' legal and medical status. In RFs, however, changes in WTP for treatment were solely dependent on the cost payers’ income. Conclusion: When clients and their families bear the full cost of treatment, cost payers' income plays a key role in preparedness for purchasing treatment services. The severity of substance use disorder is the second factor determining WTP for treatment.

Willingness to Pay, Addiction Severity, Substance Use Disorder Treatment, Methadone Maintenance Therapy, Residential Facility