title: The effect of the 'What Do You Drink' web-based brief alcohol intervention on self-efficacy to better understand changes in alcohol use over time: randomized controlled trial using ecological momentary assessment.
abstract: BACKGROUND
  To examine whether (1) the 'What Do You Drink' (WDYD) intervention resulted in drinking refusal self-efficacy (DRSE) changes directly after the intervention, and if so, whether these changes sustained at six-months follow-up and (2) DRSE was related to alcohol use over time, and if so, whether the strength of these relationships differed across conditions. Insight herein can help explain the sustained preventive effects of the WDYD intervention on alcohol use, as reported previously.
  
  
  METHODS
  Alcohol use and DRSE data were collected from 907 participants (60.3% male; M=20.8 (SD=1.7) in a two-arm parallel group randomized controlled trial applying ecological momentary assessment with 30 time-points. Participants were randomized to the experimental (n=456: WDYD intervention) or control condition (n=451: no intervention).
  
  
  RESULTS
  Latent Growth Curve (LGC) analyses that modeled individual change in DRSE over time by condition revealed that participants in the experimental condition experienced a higher social pressure DRSE compared to participants in the control condition at six-months follow-up. Moreover, LGC analyses with time-varying covariates revealed that DRSE was negatively related to weekly alcohol consumption and social pressure DRSE to frequency of binge drinking. The WDYD intervention did not affect the strength of these relationships.
  
  
  CONCLUSIONS
  The WDYD intervention increased the level of social pressure DRSE directly after the intervention that sustained at six-months follow-up. This change is likely to be responsible for the sustained preventive effects of the WDYD intervention on alcohol use, as reported previously.
authors.affiliation: Behavioural Science Institute, Radboud University Nijmegen, Nijmegen, P.O. Box 9104, 6500 HE Nijmegen, The Netherlands. Electronic address: c.voogt@bsi.ru.nl.
authors.forename: Carmen V
authors.initials: CV
authors.lastname: Voogt
authors.affiliation: Behavioural Science Institute, Radboud University Nijmegen, Nijmegen, P.O. Box 9104, 6500 HE Nijmegen, The Netherlands; Addiction Switzerland, Research Institute, P.O. Box 870, 1001 Lausanne, Switzerland. Electronic address: ekuntsche@addictionsuisse.ch.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Kuntsche
authors.affiliation: Behavioural Science Institute, Radboud University Nijmegen, Nijmegen, P.O. Box 9104, 6500 HE Nijmegen, The Netherlands. Electronic address: m.kleinjan@bsi.ru.nl.
authors.forename: Marloes
authors.initials: M
authors.lastname: Kleinjan
authors.affiliation: Behavioural Science Institute, Radboud University Nijmegen, Nijmegen, P.O. Box 9104, 6500 HE Nijmegen, The Netherlands. Electronic address: r.engels@bsi.ru.nl.
authors.forename: Rutger C M E
authors.initials: RC
authors.lastname: Engels
mesh_terms: D000428:Alcohol Drinking / Q000517:prevention & control* / Q000523:psychology* / Q000628:therapy; D005260:Female; D006801:Humans; D020407:Internet; D008297:Male; D008960:Models, Psychological; D020377:Self Efficacy; D063189:Symptom Assessment; D013813:Therapy, Computer-Assisted; D055815:Young Adult
keywords: Drinking refusal self-efficacy; Ecological momentary assessment; Heavy drinking; Students; Web-based brief alcohol intervention