Estimating under- and over-reporting of drinking in national surveys of alcohol consumption: identification of consistent biases across four English-speaking countries.

BACKGROUND AND AIMS

Questions about drinking 'yesterday' have been used to correct under-reporting of typical alcohol consumption in surveys. We use this method to explore patterns of over- and under-reporting of drinking quantity and frequency by population subgroups in four countries.

DESIGN

Multivariate linear regression analyses comparing estimates of typical quantity and frequency of alcohol consumption with and without adjustments using the yesterday method.

SETTING AND PARTICIPANTS

Survey respondents in Australia (n = 26 648), Canada (n = 43 371), USA (n = 7969) and England (n = 8610).

MEASUREMENTS

Estimates of typical drinking quantities and frequencies over the past year plus quantity of alcohol consumed the previous day.

FINDINGS

Typical frequency was underestimated by less frequent drinkers in each country. For example, after adjustment for design effects and age, Australian males self-reporting drinking 'less than once a month' were estimated to have in fact drunk an average of 14.70 (± 0.59) days in the past year compared with the standard assumption of 6 days (t = 50.5, P < 0.001). Drinking quantity 'yesterday' was not significantly different overall from self-reported typical quantities during the past year in Canada, the United States and England, but slightly lower in Australia (e.g. 2.66 versus 3.04 drinks, t = 20.4, P < 0.01 for women).

CONCLUSIONS

People who describe themselves as less frequent drinkers appear to under-report their drinking frequency substantially, but country and subgroup-specific corrections can be estimated. Detailed questions using the yesterday method can help correct under-reporting of quantity of drinking.