The Impact of Enrolment in Methadone Maintenance Therapy on Initiation of Heavy Drinking among People Who Use Heroin

Abstract

Background: There is equivocal evidence regarding whether people who use heroin substitute heroin for alcohol upon entry to methadone maintenance therapy (MMT). We aimed to examine the impact of MMT enrolment on the onset of heavy drinking among people who use heroin. Methods: We derived data from prospective, community-based cohorts of people who inject drugs in Vancouver, Canada, between December 1, 2005, and May 31, 2014. Multivariable extended Cox regression analysis examined the effect of MMT enrolment on the onset of heavy drinking among people who used heroin at baseline. Results: In total, 357 people who use heroin were included in this study. Of these, 208 (58%) enrolled in MMT at some point during follow-up, and 115 (32%) reported initiating heavy drinking during follow-up for an incidence density of 7.8 events (95% CI 6.4-9.5) per 100 person-years. The incidence density of heavy drinking was significantly lower among those enrolled in MMT at some point during follow-up compared to those who did not (4.6 vs. 16.2; p < 0.001). MMT enrolment was not significantly associated with time to initiate heavy drinking (adjusted relative hazard (ARH) 1.27; 95% CI 0.78-2.07) after adjustment for relevant demographic and substance-use characteristics. Age and cannabis use were the only variables that were independently associated with the time to onset of heavy drinking (ARH 0.74; 95% CI 0.58-0.94 and ARH 2.06; 95% CI 1.32-3.19, respectively). Conclusion: In this study, MMT enrolment did not predict heavy drinking and may even appear to decrease the initiation of heavy drinking. Our findings suggest younger age and cannabis use may predict heavy drinking. These findings could help inform on-going discussions about the effects of opioid agonist therapy on alcohol consumption among people who use heroin.

Alcohol Use Among Persons on Methadone Treatment

“…Further, other work has suggested that MMT may also decrease the initiation of heavy drinking, further underlining the beneficial effects of opioid maintenance treatment on the health of people with opioid use disorders. 5 These findings could help inform future investigations into the role of heavy alcohol use, as described by the prospective study from India, 1 in the context of maintenance therapy.…”

“…5 The primary outcomes of interest were all-cause mortality and overdose (OD) mortality. Extended Cox regression analysis examined the bivariate association between heavy alcohol use and the time to death.…”

“…1 While alcohol is found in the majority of drug-related deaths that involve illicit drugs, around the globe, 23 maintenance therapy with methadone (MMT), or buprenorphine, reduces morbidity and mortality among people who use opiates. 4 Although one common clinical challenge is comorbid alcohol use and opioid use disorder, with guidelines often recommending withholding methadone in this context given the potential for fatal overdose due to drug interactions, 5 alcohol's impact on the health outcomes of MMT patients has been “overlooked and underestimated”. 6 Therefore, we examined the impact of heavy alcohol use on mortality among MMT patients.…”

Alcohol use in opioid agonist treatment

“…For example, Caputo et al [28] demonstrated short term methadone treatment to be associated with a reduction in alcohol levels while long term methadone maintenance therapy resulted in increased alcohol consumption. While an inverse relationship between heroin use and alcohol use has previously been described [29, 30], a recent study found methadone enrolment to have no effect on heavy drinking and may even appear to decrease the initiation of heavy drinking among heroin users [31]. Furthermore, a 12-month longitudinal study of individuals with both heroin addiction and alcohol dependence demonstrated both methadone and buprenorphine to be associated with a reduction in alcohol use, with buprenorphine being more efficacious [32].…”

National Institute on Drug Abuse International Program

“…One recent study found that participation in a methadone program did not increase the prevalence of heavy drinking among participants, addressing an ongoing concern about unintended consequences of OST program participation [6]. …”