Change in substance use among patients in opioid maintenance treatment: baseline to 1-year follow-up

Abstract

Abstract Background Individuals with opioid use disorder (OUD) often have concurrent use of non-opioid substances. When patients enter opioid maintenance treatment (OMT), less is known about outcomes regarding the use of other types of drugs. Here we aimed to investigate changes in substance use among patients entering outpatient OMT, from treatment initiation to 1-year follow-up. Methods We used data from the prospective Norwegian Cohort of Patient in OMT and Other Drug Treatment Study (NorComt). Among 283 patients who entered OMT at participating facilities across Norway, 179 were assessed at follow-up. Of these patients, 131 were in a non-controlled environment, and were included in the present analysis. The main outcome was change in substance use. Logistic regression analysis was applied to identify factors associated with abstinence from all substances (other than agonist medication) at follow-up. Results Along with opioid use, most patients reported polysubstance use prior to entering treatment. No significant differences were found in baseline characteristics between the included and non-included groups when examining attrition. At the 1-year follow-up, reduced substance use was reported. While in treatment, around two-thirds of patients continued using other drugs to varying degrees. At follow-up, about one-third of patients reported abstinence from all drugs, apart from the agonist medication. Factors related to abstinence included a goal of abstinence at baseline (OR = 5.26; 95% CI 1.14–19.55; p = 0.013) and increasing age (OR = 1.05; 95% CI 1.00–1.09; p = 0.034). Conclusions The majority of patients entering OMT used other substances in addition to opioids. About one-third of patients reported abstinence at the 1-year follow up. Although the majority of patients continued co-use of other drugs while in treatment, for most substances, less than 10% reported daily use at follow-up, with the exception of cannabis which was used daily/almost daily by about 2 in 10. Higher age and treatment goal at the start of OMT were important factors related to reducing concomitant substance use during treatment. These findings suggest that many patients entering OMT are in need of treatment and support related to the use of other substances, to further improve prognosis. Clinical trial registration Clinicaltrials.gov no. NCT05182918. Registered 10/01/2022 (the study was retrospectively registered).