Episode-centred analysis of drinking to intoxication in university students

Aims: To demonstrate the use of an internet-based retrospective diary to measure intoxication and to describe the epidemiology of intoxication in a university community. Methods: A probability sample of 1564 New Zealand university students completed an Internet-based survey (82% response), including a retrospective diary in which the volume consumed on each of the preceding seven days and the duration of each episode were recorded, along with the respondent's gender, weight, and their typical quantity/ frequency of consumption, as a measure of tolerance. These parameters were used to compute an estimated blood alcohol concentration (EBAC) for each episode. Results: Using an EBAC of 0.08 g/100 ml as a criterion for intoxication produced lower estimates of incidence than binge drinking guidelines (>40 g for women, >60 g for men), or subjective reports. EBACs of 0.08 g per cent were exceeded at least weekly by 37% of women and 39% of men. Teenage females had higher EBACs than teenage males, despite lower consumption. Intoxication was positively associated with lower age, European or Maori ethnicity relative to Asian, Pacific, or other ethnicities, and with residential halls relative to other living arrangements. Faculty of study was inconsistently related to intoxication. Discussion: Frequent drinking to intoxication is normative behaviour in this population group. Of particular concern are intoxication levels in females aged 16-21 years and in males throughout their 20s. The web-based retrospective diary is a useful means of measuring intoxication by self-report. Where time permits it can be enhanced by specification of drinking locations and beverage-specific questions.