Measuring the effects of adapting a digital alcohol intervention to individuals' motives for drinking and their readiness to change

INTERVENTION: Block randomisation with random block sizes of 3 and 6 to three arms (1:1:1). All randomisation procedures will be computerised. Non‐adapted intervention: The non‐adapted intervention will be delivered to participants via their mobile phones as a toolbo Xwith si Xmodules to manipulate these critical health‐determining factors. The content of these modules is anchored in state‐of‐the‐art empirical evidence for which active ingredients are effective for supporting reduced alcohol consumption, including behaviour substitution, problem‐solving, goal setting, review of behavioural goals, self‐monitoring, normative feedback, and understanding the consequences of alcohol consumption. The core element of the intervention is a text message sent to participants each Sunday afternoon. The message includes a prompt to self‐monitor one’s current alcohol consumption and a link to a web‐based screening tool. The screening tool assesses the past week's consumption, and participants are subsequently given access to the toolbo Xwith si Xmodules. In brief, these modules consist of: 1. Normative feedback on the past week’s consumption based on age and sex. 2. Information about some of the risks of drinking alcohol, including the risk of disease, how it may affect children in proximity, injuries, and traffic accidents. 3. A goal‐setting tool with feedback on previously set goals and a timeline showing consumption over time. 4. Tips and teaching of skills which participants can use in their everyday life to immediately reduce their drinking, including tasks designed to make participants reflect on their behaviour. 5. Text messages with tips, skills, and reflection tasks that can be turned on at participants' discretion, which are then sent to participants’ mobile phones throughout the we CONDITION: Behaviour change support for individuals who want to reduce their alcohol consumption ; Not Applicable PRIMARY OUTCOME: Measured at baseline, and at 2, 4 and 8 months post‐randomisation:; 1. Past week's alcohol consumption, measured by asking about the number of standard drinks consumed each day of the past week (which are then summed); 2. Frequency of heavy episodic drinking, measured by asking about the number of episodes of heavy drinking in the past month (four or more standard drinks) INCLUSION CRITERIA: 1. 18 years of age or older 2. Have access to a mobile phone 3. Classified as drinking at risky levels according to current Swedish guidelines SECONDARY OUTCOME: Measured at 4‐month follow‐up = T2 and 8‐month follow‐up = T3:; ; Secondary outcome measures:; 1. Frequency of drinking measured using the first item of the Alcohol Use Disorders Identification Test (AUDIT‐C) (T2, T3); 2. Typical number of drinks consumed on a drinking day, measured using the second item of the AUDIT‐C (T2, T3); 3. Combined consumption measure: measured using the total score of AUDIT‐C with the primary outcome measure for frequency of heavy episodic drinking categorised into the response options of the third AUDIT‐C item (T2, T3); 4. Hazardous and risky drinking measured using the AUDIT‐C scale (T2, T3); 5. Alcohol‐related consequences measured by asking the 15‐item Short Inventory of Problems questionnaire (SIP) (T2, T3); 6. Alcohol‐related injury measured using a single item based on the SIP questionnaire concerning injuries inflicted while drinking or being intoxicated (T2, T3); 7. Use of emergency health care services measured using a single item concerning the number of visits to emergency health care services adapted from EconForm90 (T2, T3); 8. Quality of life measured using the PROMIS Global Health 1.2 items, a 10‐item questionnaire with higher scores indicating higher quality of life (T3); ; Mediation outcomes measured using face‐valid single‐item scales:; 1. Confidence: in one’s ability to reduce drinking (T2); 2. Knowledge: of how to reduce one’s drinking (T2); 3. Injunctive norms: peer’s approval of drinking (T2); 4. Descriptive norms: perceptions about other’s drinking (T2)