The sample was nearly evenly divided between males (49 percent) and females (51 percent). The participants were predominantly non-Hispanic white (91 percent), and represented both undergraduate (84 percent) and graduate students (16 percent). All but one of the study subjects was in the 18-41 year old age range, with 44 percent ages 18 to 20.
provides baseline alcohol use, baseline blackout frequency, and emergency department visits by gender. At baseline, male subjects consumed an average of 81.8 drinks over the past 28 days, while females averaged 58.7 drinks over the prior 28 days. Males drank significantly more drinks on a typical drinking day than females (7.4 vs. 5.6, p<.001). Males in the study reported significantly more heavy drinking days, defined as days with 5+ drinks for men or 4+ drinks for women, than did females (p=.008). More than half of the subjects experienced one or more blackouts in the 12 months prior to the study. Seven percent reported 6 or more blackout episodes in the year prior to study entry. Males and females in the study reported similar frequencies of baseline blackouts (p=.936).
Alcohol Consumption, Blackout Frequency, and Emergency Department (ED) Visits Among High-Risk College Drinkers (n=954)
As indicated in , 30 percent of the males and 27 percent of the females in the study visited the ED at least once during the 24-month follow-up. Overall, there were 404 ED visits among the 954 study participants over a 2-year observation period. The severity of ED visits varied, from stitches and broken bones, to CT scans for head or brain injury. A prior examination of the study sample revealed that 25 percent of subjects reported an alcohol-related injury during 2-year follow-up.30
Students were not asked to specify if alcohol was a factor in their ED visits, but the correlation between ED visit rates and self-reported alcohol-related injury rates was strong (r=0.15, p<.001).
The multivariate general estimating equation analyses results are presented in . The outcome variable is the rate ratio of emergency department visits among students who experienced alcohol-induced blackouts compared to subjects who did not. In the unadjusted model, blackouts at baseline were strongly associated with the rate of emergency department visit during follow-up, increasing from 1.21 (95 percent CI: 1.06-1.37) for subjects reporting 1-2 blackouts at baseline to 1.96 (1.48-2.50) for students acknowledging 6+ blackouts at baseline. After adjusting for age, race/ethnicity, gender, weight, sensation-seeking, experiment group status, alcohol quantity and heavy drinking day frequency in the full generalized estimating equations model, the rate ratios of emergency department visits were 1.09 (95 percent CI: 0.94-1.27) for subjects reporting 1-2 blackouts, 1.39 (95 percent CI: 1.12-1.71) for students reporting 3-5 blackouts, and 1.75 (95 percent CI: 1.31-2.36) for participants acknowledging 6+ blackouts in the 12 months prior to the trial.
Repeated Measures GEE Model for Emergency Department Visits during 24-Month Follow-Up among High-Risk College Drinkers
The proportion of emergency department visits during follow-up was also related to baseline blackout frequency. Subjects reporting no blackouts at baseline made up roughly 50 percent of the sample, but reported less than 40 percent (n=160) of the total ED visits. On the other hand, participants with 6+ blackouts comprised 7 percent of the sample, but experienced 11 percent (n=45) of the total emergency department visits. The group with the largest contribution to blackout-associated ED visits was the 3-5 blackout group, where 15 percent of the subjects were responsible for 21 percent (n=83) of all ED visits. The total attributable risk from all blackout categories combined was 12.8 percent. This indicates that out of 404 total ED visits in the sample, 52.7 of these visits (95% CI: 27.9-69.4) were emergency department visits associated with blackout drinking.
provides the breakdown of ED costs associated with blackouts based on various estimates of ED unit value cost. The mean Medical Expenditure Panel Survey ’06 payment per emergency department visit was $638. Adjusting for inflation and adding $68 per visit for ambulance transport cost generates an average ED visit cost of $809 from the MEPS ’06 data set. The Wisconsin Hospital Association average billing cost per emergency department visit was $675 in 2003 dollars. Adjusting to 2010 dollars and adding ambulance transport costs yields an average of $950 per emergency department visit from the 2003 Wisconsin data set.
Costs of Blackout Associated Emergency Department (ED) Visits
Applying average emergency department utilization costs to the blackout associated visits (52.7), the ED medical expenditures associated with blackouts were $43,000 over a 24-month period using national MEPS estimates and $50,000 using Wisconsin data figures. On a per blackout drinker, per year basis in this sample of high-risk college drinkers, blackout costs averaged $46.92 per blackout drinker per year in the national data and $54.55 in the Wisconsin data. To put the results in perspective, on a campus-wide basis at a university of 40,000 students, with 25percent of students experiencing blackouts,1
emergency department costs due to blackouts would range from $469,000 (MEPS) to $546,000 (Wisconsin Hospital Association) per year.