This was assessed as: ‘over the past 12 months, on how many days did you drink five or more alcoholic drinks in a row?’ and ‘over the past 12 months, on how many days have you got drunk on alcohol?’. Both indices of drinking behaviour have been used to define problem drinking in previous research [1,2,31]. Response options ranged from 1 (never) to 5 (most days). Scores were strongly associated (Spearman's r = 0.69), and combined whereby the highest endorsement from either behaviour was taken as the measure of problem alcohol use. For the present analysis, individuals were recoded into those who had never drunk alcohol in their life, those who had not engaged in problem alcohol use more than twice in the last year and those who had engaged in problem alcohol use more than twice in the last year (i.e. drinking until drunk or drinking five or more drinks in a row in the last year).
