The overall evaluation strategy for the DWAW programme has been designed to assess the combined impact of all the interventions on alcohol consumption and at-risk drinking in people aged 50 and over. This will be done using a large-scale postal survey. Qualitative interviews with DWAW staff and participants will further explore how the interventions were received and how they may have contributed to change in alcohol use for people aged 50 + .
Quantitative survey data of people aged 50 and over
An anonymous postal questionnaire will be sent to 76,000 people aged 50 and over registered with a general practice in the demonstration and control areas. The questionnaire will collect information on alcohol use (AUDIT) [
25], alcohol use frequency, units consumed, reasons for use, knowledge of alcohol units etc.), health (SF-12) [
40] and healthcare use. All participants will be provided with a written study information sheet and it will be made clear that completion and return of the questionnaire implies consent to take part.
The questionnaires will be completed in two waves; the first wave will be prior to implementation of the programme (year 1), the second wave will be at the end of the programme (year 5). The questionnaire will be sent to the same individuals at both time-points linked by a unique identification number. Personally identifiable data will not be collected as part of the questionnaire. To recruit participants, 3 GP practices in each demonstration and control area will use the Health Informatics Centre at the University of Dundee to send a questionnaire, postage paid envelope and covering letter to all over 50’s on their practice lists asking them if they would like to participate in the study. In Scotland, Wales and England, a GP will check the list of participants beforehand for suitability (e.g. patients nearing the end of life or who don’t have the capacity to consent will be removed). In Northern Ireland, this task will be carried out by a Clinical Research Nurse from Northern Ireland CRN (Primary Care) in conjunction with a GP. Patient names and addresses will not be made available to the research team and only the research team will have access to the data.
Questionnaires will take approximately 15 min to complete. Participants will be able to return the completed questionnaires directly to the research team in a pre-paid envelope or complete it on their mobile phone, tablet or PC. We anticipate a 35% response rate. Returned questionnaires will be electronically scanned and stored on password protected computers. If participants do not complete a questionnaire in Wave 1 (pre-programme), they will not be sent a questionnaire in Wave 2 (post-programme).
At the end of the programme (year 5) the questionnaire will be sent to all participants who completed the questionnaire at wave 1. A written reminder will be sent if participants have not responded within two weeks, with a second reminder sent after 1 month.
The aim of the questionnaire survey is to establish if there has been a reduction in alcohol consumption, at-risk drinking and alcohol-related problems in over 50’s in the demonstration areas, as well as measuring programme reach and awareness of campaign messages.
The sample size calculation is based on detecting a reduction of 2 alcohol units per week in the intervention groups (i.e. demonstration areas). For the purposes of this calculation this will be re-phrased as a difference in the average reduction between the two groups, if there is no identified difference in the average consumption of the control group then these two definitions are comparable.
An estimate of overall consumption in the over-50’s including the 17% of over 50’s who abstain or drank nothing in last year comes from the General Lifestyle Survey 2010 [
42] and is given as a mean of 10.7 with an SD of 17.4, so the effect size will be 2/17.4, rounded to approximately 0.1. Consulting Cohen [
41], Table 2.4.1 (p55), and taking a power of 0.80, type I error of 0.5, and an effect size of 0.1 gives a sample size of 1571 for each group.
A complete or partial response was obtained in the General Lifestyle Survey 2010 [
42] for of the order of 70%, with design effects generally of the order or 1.2 to 1.3 or less. Thus, allowing for non-response, design effects and males and females separately results in a sample size of 5500 per group (i.e. demonstration or control area).
Regression modelling will be used to assess the differences between the intervention and comparison groups at baseline and post intervention. Due to the quasi-experimental, serial cross-sectional design, difference-in-differences analyses will be conducted using logistic and linear regression for dichotomous and continuous outcomes, respectively.
Qualitative evaluation
The qualitative evaluation of DWAW aims to explore how interventions are experienced; how they may work to bring about change and to identify areas for practice improvements. The qualitative evaluation will also explore if DWAW is meeting the needs of minority groups and over 50’s experiencing different life stages and circumstances.
Semi-structured interviews will be conducted with people who have received structured alcohol support or taken part in the DWAW resilience course. Focus groups will be conducted with recipients of the DWAW group interventions (e.g. peer support groups, social activity groups). Participant case studies using photo elicitation will also be completed in each of the demonstration areas to explore the relationship with alcohol and any change in use. Photo elicitation involves the participant making a visual record of their lives whilst they are engaged with DWAW; this is then used to generate discussion during interview. Focus groups will be conducted with DWAW staff throughout the programme, and individual interviews will be conducted with stakeholders (professionals involved in multi-agency working with DWAW). All interviews will be audio-recorded and will take no longer than one hour. Interviews will be transcribed verbatim and will be analysed using a framework approach [
43].
The findings of this study will be disseminated at both national and international conferences and published in peer-reviewed journals.