People who drink alcohol were defined as having an AUDIT score of 1-40 and non-drinkers as having an AUDIT score of 0.19 Those people who drink alcohol were further categorised into those at risk of alcohol dependence as having an AUDIT score ≥20 and those not at risk of alcohol dependence as having an AUDIT score of 1-19. Descriptive statistics for non-drinkers were included in RQs 1 and 2 to provide wider context to smoking prevalence and smoking and smoking cessation attempt characteristics. Non-drinkers were not included in RQ3 where the primary contrast of interest was between drinkers at risk and drinkers not at risk of alcohol dependence, and non-drinkers are a heterogeneous group including both former drinkers (many of whom have given up drinking for health reasons) and long-term or lifetime abstainers.22
