Supporting women who have served in the Armed Forces with a smartphone app to reduce alcohol consumption: A Randomized Controlled Trial

Background: Alcohol misuse is common in the UK Armed Forces (AF) community, with prevalence higher than in the general population. To date, digital health initiatives to address alcohol misuse have largely focused on men, who represent around 88% of the UK AF. However, women who have served in the UK AF also drink disproportionately more than women in the general population. Objective: This two-arm participant-blinded (single-blinded) confirmatory randomized controlled trial (RCT) aimed to assess the efficacy of a brief alcohol intervention (DrinksRation) compared to a web application which included NHS-focused drinking advice (BeAlcoholSmart) in reducing weekly self-reported alcohol consumption between baseline and 84-day follow-up among women who have served in the UK AF. Methods: A smartphone app (DrinksRation) was compared with government guidance on alcohol use. The app included features tailored to the needs of women who have served and was designed to enhance motivation to reduce alcohol consumption. The trial enrolled women who had completed at least one day of paid service in the UK Armed Forces. Recruitment, consent, and data collection were completed automatically through the platform. The primary outcome was the between-group difference in change in self-reported weekly alcohol consumption from baseline to day 84, measured using the Timeline Follow-Back method. The secondary outcome was the between-group difference in change in Alcohol Use Disorders Identification Test (AUDIT) score from baseline to day 84. Process evaluation outcomes included app engagement and usability, with usability assessed using the mHealth App Usability Questionnaire. Results: A total of 88 women UK AF veterans were included in the final analysis (control=37; intervention=51). At 84 days post-baseline, participants in the intervention group (DrinksRation) showed a greater reduction in weekly alcohol consumption compared to controls (BeAlcoholSmart) (adjusted mean difference in change from baseline = -11.6 units; 95% CI: -19.7 to -3.6; p=0.005). AUDIT scores decreased more in the intervention group (adjusted mean difference in change = -3.9; 95% CI: -6.9 to -1.0; p=0.01). Usability scores at day 28 were significantly higher for the intervention group across all domains. No serious adverse events or technical issues were reported. Conclusions: DrinksRation reduced alcohol consumption and hazardous drinking among women who have served in the UK Armed Forces. Engagement was strong, usability was high, and no safety concerns were identified. These findings support the potential of tailored digital interventions to address alcohol misuse in women who have served in the UK Armed Forces. Registration: ClinicalTrials.gov (trial registration: NCT05970484).