College students' responses to a 5/4 drinking question and maximum blood alcohol concentration calculated from a timeline followback questionnaire

Abstract

Objective: Many surveys employed to study college drinking ask whether students have had a five-drink (for men) or four-drink (for women) episode in one sitting at least once during the previous 2 weeks to indicate risky or heavy episodic drinking. However, some researchers have questioned the predictive validity of the 5/4 measure. This study tested whether such students attained extremely high blood alcohol concentrations (BACs) during the previous 30 days. Method: Freshmen students were recruited by presentation of short screening surveys in the classroom or outside the student stores. Students who reported a risky drinking episode were invited to enroll in the study and were given a lengthy survey battery that included a computerized 30-day Timeline Followback recall of their drinking. The amount of alcohol consumed was used along with each subject's gender and weight to calculate an estimated BAC (eBAC) for each event and the maximum eBAC taken for this report. Results: Fifty-five percent of the 953 students who completed the screening survey met criterion for enrollment, and 381 students entered the study. The average peak calculated eBAC was 233 mg/dl. Only 9.2% of subjects did not have an eBAC value at or above the threshold for a driving while intoxicated offense, 80 mg/dl. Conclusions: Students who report one recent risky drinking episode are very likely to have had at least one heavy drinking episode that generated a BAC in excess of the threshold for driving while intoxicated. Many report extremely high consumption levels. The 5/4 screening question is highly predictive of abusive drinking and can be used to identify students at severe risk for adverse events related to the consumption of alcohol. (J. Stud. Alcohol Drugs 70: 601-605, 2009)