Effectiveness of brief alcohol interventions for general practice patients with problematic drinking behavior and comorbid anxiety or depressive disorders

Background: Brief interventions (BIs) are effective methods to reduce problematic drinking. It is not known, if the effectiveness of BI differs between patients with or without comorbid depression or anxiety disorders. Methods: In a randomized controlled BI study with two intervention groups and one control condition, data were collected from 408 general practice (GP) patients with alcohol use disorders, at-risk drinking or binge drinking. 88 participants were diagnosed with comorbid anxiety and/or depressive disorders. The effectiveness of BI was assessed at a 12-month follow-up in relation to the presence and absence of comorbidity. Reduction of drinking in six ordered categories (g/alcohol) between baseline and follow-up served as the outcome variable. Results: BI were significantly related to reduction of drinking in the non-comorbid (-2.64 g/alcohol vs. -8.61 g/alcohol; p = .03) but not in the comorbid subsample (-22.06 g/alcohol vs. -22.09 g/alcohol; p = .76). Compared to non-comorbid participants, a significantly higher reduction of drinking was found for comorbid individuals (-6.55 g/alcohol vs. -22.08 g/alcohol; p = .01). An ordinal regression analysis revealed comorbidity to be a positive predictor for reduction of drinking (estimator = .594; CI = .175-1.013; p < .01). When entering the variables amount of drinking at baseline, intervention and classification of problematic drinking, these became significant predictors, whereas comorbidity showed only a tendency. Conclusion: BI did not significantly effect a reduction of drinking in comorbid patients. As BI are known to be less effective for dependent drinkers, a larger proportion of dependents among the comorbid might have limited the effectiveness of BI. Future studies with larger sample sizes of comorbid problem drinkers are necessary to confirm the results.