Misuse of opioid drugs may affect the outcomes of treatment for alcohol use disorder, and cannabis use may predict the odds of heavy drinking at the end of treatment, according to a study published in Alcoholism: Clinical and Experimental Research.

A total of 1226 patients with alcohol dependence were randomly assigned to 1 of 9 groups receiving acamprosate and/or naltrexone, or placebo as well as medical management and/or behavioral intervention (COMBINE study). Active treatment or placebo was administered for 16 weeks, with follow-up assessments performed at 26, 52, and 68 weeks. Alcohol use was assessed during the 120-day-long treatment and one year after treatment. Opioid misuse and cannabis and other drug use were assessed 6 months before enrollment, and adherence to treatment was also evaluated (ie, naltrexone, acamprosate, or placebo).

During therapy, the odds of heavy drinking were 38% greater in participants who misused opioid medications (odds ratio [OR] 1.38 [95% CI, 1.13-1.64]; P =.001). Cannabis use raised the odds of heavy drinking during treatment by 19% (OR=1.19; P =.01) and was associated with 29% greater odds of drinking in any amount (OR=1.29; P <.001). The use of any other drug had a predictive value for heavy drinking of 20% (OR=1.20; P =.01), and the use of any other drug was associated with 23% greater odds of drinking in any amount (OR=1.23; P =.007).

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Opioid misuse was associated with heavy and more frequent drinking at the end of the treatment period (OR=2.90 [95% CI, 1.43-5.90]; P =.003). In addition, misuse of opioid medications predicted being a heavy and more frequent drinker at one year after treatment (OR=2.66 [95% CI, 1.26-5.59]; P =.01). Misuse of opioids, cannabis, and use of other drugs predicted treatment adherence in patients with heavy drinking (P <.001; P =.004; and P =.028, respectively). Cannabis use only, opioid misuse, and other drug use were all significant predictors of frequent vs infrequent heavy drinking during treatment (P <.04).

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 “These findings strongly suggest that clinicians treating [alcohol use disorder] should assess opioid misuse and cannabis and other drug use as potential barriers to medication adherence and potential relapse triggers…[and] clinicians should address the co-use of other substances and carefully monitor treatment adherence,” concluded the study authors.

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Witkiewitz K, Votaw VR, Vowles KE, Kranzler HR. Opioid misuse as a predictor of alcohol treatment outcomes in the COMBINE study: mediation by medication adherence [published online June 5, 2018]. Alcohol Clin Exp Res. doi: 10.1111/acer.13772