Alcohol use across trials of psychological interventions for bipolar: A systematic review and meta-analysis

Background: Current clinical guidelines recommend psychological interventions for the management of bipolar disorder (BD). However, despite a substantial proportion of individuals with BD experiencing an alcohol use disorder (AUD), it is not established how frequently individuals with AUD are excluded from trials of psychological interventions for BD, or whether this exclusion impacts trial efficacy. 
Methods: A systematic review of randomized controlled trials of psychological interventions for BD was conducted, to investigate the proportion of trials excluding individuals with AUD and/or measuring alcohol use at follow-up. Random effects meta-analyses with subgroup comparisons were also conducted, to investigate whether the difference in depressive and manic symptoms at follow-up between participants in the intervention and comparator conditions was significantly different between trials including and excluding individuals with AUD.  
Results: Across the 89 trials identified, 26 (29.2%) reported alcohol-related exclusion, whilst only 3 (3.4%) measured alcohol use at follow-up. The pooled effect size for neither depressive nor manic symptoms significantly differed between trials including or excluding individuals with AUD (Q = 0.48, p = .49, and Q = 0.60, p = .44, respectively).
Conclusions: Overall, alcohol-related exclusion is common across trials of psychological interventions, but intervention efficacy does not significantly differ between trials including and excluding individuals with AUD. We would therefore recommend that intervention studies do not exclude people with AUD, in order for evidenced-based treatment to be evaluated in those with co-occurring problems.