This study examines the longitudinal relationships between quantity of alcohol consumed and self-rated intoxication level while driving, reported daily over a two-year period, by means of an automated touch-tone interactive voice response (IVR) system. For 736 consecutive days, subjects (n = 33 male social drinkers) reported beer, liquor, and wine consumption during the previous 24-hour period. They also provided daily ratings on 11-point scales for a number of variables, including: (1) "highest level of intoxication yesterday", and (2) "highest level of intoxication while driving yesterday". Two subjects with highly predictable weekly drinking patterns throughout the 2-year study period were selected for detailed analysis on the above variables. Blood alcohol concentration (BAC) values were estimated, and official driver records were examined. Both subjects drink at bars frequently, regularly, and heavily, and also drive away from bars at subjective levels of intoxication that suggest an impairing or an even illegal BAC. The present study demonstrates that the IVR method allows the assessment of longitudinal predictability of drinking and drink-driving behaviour for up to two years, with inherent statistical stability.
Samenvatting