title: Evaluating the effectiveness of a smartphone app to reduce excessive alcohol consumption: protocol for a factorial randomised control trial.
abstract: Excessive alcohol consumption is a leading cause of death and morbidity worldwide and interventions to help people reduce their consumption are needed. Interventions delivered by smartphone apps have the potential to help harmful and hazardous drinkers reduce their consumption of alcohol. However, there has been little evaluation of the effectiveness of existing smartphone interventions. A systematic review, amongst other methodologies, identified promising modular content that could be delivered by an app: self-monitoring and feedback; action planning; normative feedback; cognitive bias re-training; and identity change. This protocol reports a factorial randomised controlled trial to assess the comparative potential of these five intervention modules to reduce excessive alcohol consumption.
  
  
  
  A between-subject factorial randomised controlled trial. Hazardous and harmful drinkers aged 18 or over who are making a serious attempt to reduce their drinking will be randomised to one of 32 (2(5)) experimental conditions after downloading the 'Drink Less' app. Participants complete baseline measures on downloading the app and are contacted after 1-month with a follow-up questionnaire. The primary outcome measure is change in past week consumption of alcohol. Secondary outcome measures are change in AUDIT score, app usage data and usability ratings for the app. A factorial between-subjects ANOVA will be conducted to assess main and interactive effects of the five intervention modules for the primary and secondary outcome measures.
  
  
  
  This study will establish the extent to which the five intervention modules offered in this app can help reduce hazardous and harmful drinking. This is the first step in optimising and understanding what component parts of an app could help to reduce excessive alcohol consumption. The findings from this study will be used to inform the content of a future integrated treatment app and evaluated against a minimal control in a definitive randomised control trial with long-term outcomes.
  
  
  
  ISRCTN40104069 Date of registration: 10/2/2016.
authors.affiliation: Department of Clinical, Educational and Health Psychology, University College London, 1 -19 Torrington Place, London, WC1E 7HB, UK. c.garnett.12@ucl.ac.uk.
authors.forename: Claire
authors.initials: C
authors.lastname: Garnett
authors.affiliation: Department of Clinical, Educational and Health Psychology, University College London, 1 -19 Torrington Place, London, WC1E 7HB, UK.
authors.forename: David
authors.initials: D
authors.lastname: Crane
authors.affiliation: Department of Clinical, Educational and Health Psychology, University College London, 1 -19 Torrington Place, London, WC1E 7HB, UK.|National Centre for Smoking Cessation and Training, London, UK.
authors.forename: Susan
authors.initials: S
authors.lastname: Michie
authors.affiliation: Cancer Research UK Health Behaviour Research Centre, University College London, London, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: West
authors.affiliation: Department of Clinical, Educational and Health Psychology, University College London, 1 -19 Torrington Place, London, WC1E 7HB, UK.|Cancer Research UK Health Behaviour Research Centre, University College London, London, UK.
authors.forename: Jamie
authors.initials: J
authors.lastname: Brown
mesh_terms: D000437:Alcoholism / Q000517:prevention & control*; D002681:China; D006801:Humans; D063731:Mobile Applications; D012107:Research Design; D000068997:Smartphone; D011795:Surveys and Questionnaires
keywords: Alcohol; App; BCT; Digital; Drink; Excessive; Intervention; RCT; Smartphone