Validity of self-reported alcohol consumption in nondependent drinkers with unintentional injuries.
BACKGROUND
Self-report has become an anchor for alcohol assessment in the acute and primary care populations. The purpose of the study was to determine the validity of self-reported alcohol consumption after unintentional injuries in hospitalized, nondependent drinkers.


METHODS
Non-alcohol-dependent subjects 18 years of age and older with unintentional injuries (n = 209) were enrolled in the study and were interviewed if they had either an admitting blood alcohol concentration (BAC) > or = 10 mg/dl (0.01 g/dl) or a positive screen for a history of problem drinking. The self-reported number of standard drinks, time that drinking commenced, sex, and weight were used to calculate estimated blood alcohol concentration (EBAC), which was then compared to the admission BAC.


RESULTS
We had data to calculate the EBAC on 141 of the 209 subjects. Seven men and no women with positive (> or = 10 mg/dl) BAC denied drinking. Of the 134 subjects for whom we had data to calculate EBAC and who acknowledged drinking, mean BAC was 147.06 mg/dl and mean EBAC was 68.66 mg/dl. For women (n = 30), mean BAC was 149.53 mg/dl and mean EBAC was 114.67 mg/dl; for men (n = 104), mean BAC was 146.35 mg/dl and mean EBAC was 55.38 mg/dl. The Spearman's p between laboratory BAC and EBAC was 0.461 (p < 0.001) for all subjects (n = 134), 0.275 (NS) for women (n = 30), and 0.532 (p < 0.001) for men (n = 104). For women and men separately, multiple regression analyses were performed to predict BAC by using weight and reported number of drinks. For women, weight and number of drinks accounted for 3% of the variance in laboratory BAC [r = 0.181, F(2,47) = 0.797,p = NS]. In contrast, for men these same predictors accounted for 34% of the variance [r = 0.585, F(2,135) = 35.203,p < 0.001).


CONCLUSIONS
Most nondependent patients with unintentional injury acknowledged drinking before injury. After injury, women and men have different patterns of reporting their drinking, with men more frequently underreporting but reporting more accurately and women more random in their self-reports.