Substance of choice, impact of heroin or opium on treatment retention in a multicentre randomised controlled trial in Iran.

Abstract

In the Middle East and Asia, illicit opioid use exists across a spectrum between heroin and opium. The impact of primary opioid of choice on opioid agonist treatment retention has not been well evaluated previously, especially for opium tincture, an increasingly popular form of opioid agonist treatment in Iran. This study investigates the relationship between primary opioid of choice, namely heroin or opium, and retention in opium tincture and methadone treatment. Participants with opioid use disorder (n=204) were randomised to receive opium tincture or methadone. All participants were categorised as mainly using opium or heroin. Bivariate analyses between treatment retention and primary opioid of choice (P < 0.05) and logistic regression were conducted. Among the 191 participants included in this analysis, heroin was the primary substance of choice for 135 participants (70.7%) and opium for 56 (29.3%). Bivariate analysis showed that the opium group was more likely to be satisfied with family situation, employed and retained in treatment than the heroin group while less likely to experience incarceration and use multiple substances. When adjusting for covariates, primary opioid of choice was not significantly associated with retention in either methadone or opium tincture treatment arm. Positive factors, such as employment, housing and family support, seem to collectively explain the higher retention in treatment among those who primarily use opium compared to those who use heroin. To optimise retention in opioid agonist treatment, biopsychosocial care models should be further evaluated to improve psychosocial functioning.