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The effect of alcohol strength on consumption
Last registered on June 17, 2017

Pre-Trial

Trial Information
General Information
Title
The effect of alcohol strength on consumption
RCT ID
AEARCTR-0002266
Initial registration date
June 16, 2017
Last updated
June 17, 2017 2:57 AM EDT
Location(s)
Primary Investigator
Affiliation
Oxford Brookes University
Other Primary Investigator(s)
PI Affiliation
Oxford Brookes University
PI Affiliation
Oxford Brookes University
Additional Trial Information
Status
In development
Start date
2018-04-06
End date
2019-07-31
Secondary IDs
Abstract
Background:
Alcohol is consumed by 79% of people (aged 16+) in the United Kingdom (UK), many of whom are drinking in excess of the recommended guidelines. Alcohol consumption can impair long-term health, lead to intentional and non-intentional harm to the self and others, and incurs a large financial burden on society. As yet, no single intervention has proved effective in reducing alcohol consumption across the entire alcohol-consuming population.

Design/Methods:
A multi-centre, double-blind, randomised, controlled, cross-over trial, to assess the effect of alcohol strength on consumption. The trial will be based within licensed premises in the South East of England. Participants (n=67) will be randomised to the order they receive the intervention product (3.5% lager or 9.5% white wine) and the control product (4.8% lager or 13% white wine). They will consume their specified alcohol products ad libitum during two study sessions within a normally functioning licensed premises. The primary outcome measure is mean difference in UK units of alcohol consumed in the reduced-strength alcohol condition compared with the regular-strength alcohol condition. Participants’ experiences of consuming reduced-strength alcohol will be explored by administering a questionnaire at the end of the study sessions. The questionnaire will also ascertain whether participants were aware of the strength of the alcohol they were consuming, and whether this differed between conditions.

Discussion:
Study results will seek to inform academics of the feasibility of the study protocol in practice and supply data with which to calculate accurate sample sizes for future larger-scale studies. The study results may inform policy makers about whether reducing the strength of alcohol is an effective intervention to reduce alcohol consumption within licensed premises.

External Link(s)
Registration Citation
Citation
Davies, Dr, Professor Foxcroft and Parvati Perman-Howe. 2017. "The effect of alcohol strength on consumption ." AEA RCT Registry. June 17. https://doi.org/10.1257/rct.2266-2.0.
Former Citation
Davies, Dr et al. 2017. "The effect of alcohol strength on consumption ." AEA RCT Registry. June 17. http://www.socialscienceregistry.org/trials/2266/history/18760.
Experimental Details
Interventions
Intervention(s)
Reduced-strength lager (3.5% ABV) or reduced-strength white wine (9.5% ABV): participants will choose, prior to their first study session, whether they would prefer to drink lager or white wine during the trial.
Intervention Start Date
2018-04-06
Intervention End Date
2018-10-31
Primary Outcomes
Primary Outcomes (end points)
Primary outcome:
The mean difference in UK units of alcohol consumed in the intervention arm (reduced-strength alcohol) compared with the control arm (regular-strength alcohol). UK units will be converted to, and additionally displayed as, grams of alcohol for a non-UK audience.

Secondary outcomes:
1. The proportion of participants who consumed ≥27% fewer units in the intervention arm compared with the control arm.
2. The mean difference in participants’ BACs upon leaving the licensed premises in the intervention arm compared to the control arm.

Non efficacy outcomes:
1. The mean difference in participants’ perceived enjoyment when drinking the intervention drinks compared to the control drinks.
2. The mean difference in how pleasant participants perceived the taste of the intervention drink compared to the control drink.
3. The mean difference in participants’ perceived intoxication having consumed the intervention drinks compared to the control drinks.
4. The proportion of participants who perceived the intervention product to taste equally as nice as, or nicer than, their normal drink.
5. The proportion of participants who would consider switching from their regular brand/product to the intervention product and the proportion of these for whom the intervention product is lower strength than their regular brand/product.
6. The proportion of participants who can specify the brand and strength of the product they were consuming in the intervention arm, and the control arm.
7. The mean difference in the number of non-alcoholic drinks consumed by participants in the intervention arm compared to the control arm.
8. The mode of the main reasons stated for drinking non-alcoholic drinks in the intervention arm, and the control arm.
9. The mean difference in the number of units that participants consumed after their study session (but on the same day/evening of their study sessions) in the intervention arm compared with the control arm. This will also be displayed as grams of alcohol for a non-UK audience.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
A multi-centre, double-blind, randomised, controlled, cross-over trial. The trial will be based within licensed premises in the South East of England.
Experimental Design Details
Between two and five licensed premises will be recruited to host a minimum of four study sessions each. Hosting venues will help to recruit 67 participants via social media posts and by placing flyers and posters within their premises. Potential participants will contact the researcher who will provide them with an information sheet and invite them to undertake an electronic screening questionnaire. Eligible participants will be contacted by the researcher to arrange two study sessions within the same venue. Participants' study sessions will be approximately one month apart, occurring at the same time of day, on the same day of the week and on approximately the same date of the month. Upon arrival for the first study session, participants will undertake a breath alcohol concentration (BAC) test and, if their BAC reading is ≤35mcg/100ml breath, they will be asked to consent to partake in the trial. Consented participants will be randomised to the order in which they receive the intervention and the control. Participants will be briefed to act as they normally would whilst in the licensed premises, but when they want to purchase an alcoholic drink from the normal bar they will exchange money for a drink token. Participants will only be allowed to purchase one drink token per visit to the bar. The participant will take the token to a makeshift bar area, which will be manned by a research assistant (RA) who will exchange the token for a study-specific drink. The study-specific drinks containers will be de-labelled and a colour-coding system will be applied to notify the RA of which drink to provide. The RA will stamp the participant's randomisation card each time a drink is supplied. Participants will drink ad libitum during study sessions, and, when they wish to leave the venue and conclude their study session, they will undertake a BAC test, complete an exit questionnaire and hand their randomisation card to the researcher. When participants return for their second study session they will repeat the process, aside from consent and randomisation. They will be given a new randomisation card, which will display the colour code for the opposing product (intervention or control). When participants have completed their second study session they will be given an alcohol information leaflet to retain. All trial participants who have satisfactorily completed a consent form will be automatically entered into a free prize draw to win one prize of £250. Participants may opt out of the free prize draw by checking a box on the consent form.
Randomization Method
Randomisation of the order that participants receive the intervention and the control. The randomisation will be conducted in an office using online randomisation software.
Randomization Unit
Individual.
Was the treatment clustered?
No
Experiment Characteristics
Sample size: planned number of clusters
134 observations from 67 alcohol consumers.
Sample size: planned number of observations
134 observations from 67 alcohol consumers.
Sample size (or number of clusters) by treatment arms
67 alcohol consumers to receive both the intervention, and the control during separate study sessions.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
0.3977 UK units of alcohol consumed, (±5.23), 95% confidence level, 80% power.
Supporting Documents and Materials

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IRB
INSTITUTIONAL REVIEW BOARDS (IRBs)
IRB Name
Oxford Brookes University Science and Technology Sub-Committee.
IRB Approval Date
2017-05-18
IRB Approval Number
N/A
IRB Name
Oxford Brookes University's Research Ethics Committee.
IRB Approval Date
2017-03-24
IRB Approval Number
171086
Analysis Plan

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Post-Trial
Post Trial Information
Study Withdrawal
Intervention
Is the intervention completed?
No
Is data collection complete?
Data Publication
Data Publication
Is public data available?
No
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)
REPORTS & OTHER MATERIALS