A comparative analysis of different methods for obtaining estimates of alcohol consumption in a Danish population survey

Aims: The aim of the present study was to compare different measures of alc ohol consumption used in a Danish survey. Methods: A stratified random samp le was extracted frorn the Civil Registration System. From January 1997 to January 1998 approximately 8 telephone interviews were conducted every day. including Sundays and holidays, ending With a total of 3,050 interviews af ter 1 year. Two main approaches to measure alcohol consumption were used: t he quantity-frequency and the recent occasion approaches: the latter is sub divided into previous Week and Previous day approaches. Results: The overal l estimated number of units (= 12 g of pure alcohol) per week was 6.8 (95% confidence intervals (CI): 6.5-7.1). 6.7 (95% Cl: 6.4 7.1) and 8.5 (95%. CI : 7.8-9.1) for the quantity frequency. previous Week and previous day appro aches, respectively. A total of 50% of the men and 70% of the women did not drink alcohol the previous day. Among people classified as high consumers in the previous week and previous day approaches, less than 60% and 30% res pectively, were similarly classified in the quantity frequency approach. Co nclusion: There was agreement on the level of alcohol consumption between t he quantity frequency and previous week approaches. but higher estimates wh en using the previous day approach. The previous day approach varied more i n relation to the interview day and season compared With the quantity-frequ ency approach and the previous week approach. The recent occasions approach showed some difficulties in classifying the individuals. If the alcohol co nsumption is included in a model as a risk indicator or a confounder. the q uantity-frequency approach Would be more preferable than the recent occasio n approach.