Background
Participation in temporary alcohol abstinence campaigns such as ‘Dry January’ may prompt enduring reductions in alcohol consumption. A randomized controlled trial (RCT) is required to establish any long-term benefits or negative consequences of temporary abstinence. In the present study, we randomized heavy drinkers to complete or intermittent alcohol abstinence for 4 weeks, in order to evaluate the feasibility of conducting a large-scale RCT.

Methods
This was a mixed methods feasibility study in which we explored recruitment and retention to a randomized trial, compliance with alcohol abstinence instructions and barriers to compliance, and acceptability of study procedures (primary feasibility outcomes). A community sample of women aged between 40 and 60 who drank in excess of 28 alcohol units per week were randomized to abstain from alcohol for 4 weeks either completely or intermittently (at least four abstinent days per week). To monitor compliance, both groups provided regular breath samples on a cellular breathalyser. A subsample completed a semi-structured interview that probed barriers to compliance with abstinence instructions and acceptability of study procedures.

Results
Within 5 months, we recruited, screened and randomized 25 participants (20% of participants who responded to advertisements: 14 in the complete abstinence group, 11 in the intermittent abstinence group), 24 of whom were retained throughout the 28-day intervention period. Participants in both groups tended to comply with the instructions: the median number of breathalyser-verified abstinent days was 24 (IQR = 15.5–25.0; 86% of target) in the complete abstinence group versus 12 (IQR = 10–15; 75% of target) in the intermittent abstinence group. Semi-structured interviews identified some barriers to compliance and methodological issues that should be considered in future research. No adverse events were reported.

Conclusions
It is feasible to recruit heavy drinking women from community settings and randomize them to either complete or intermittent abstinence from alcohol for 4 weeks. The majority of participants were retained in the study and compliance with the abstinence instructions was good, albeit imperfect. A comprehensive RCT to compare temporary alcohol abstinence with other alcohol reduction strategies on long-term alcohol consumption is feasible. Findings from such a trial would inform implementation of alcohol campaigns and interventions.