Alcohol effects on motor vehicle crash injury.

CONTEXT

Although alcohol is frequently present in injured patients, whether it exacerbates injury and whether tolerance to alcohol changes such a relationship is less clear. Most clinical studies do not consider other important predictors of injury, making interpretation of their findings problematic.

OBJECTIVE

To examine alcohol's role in injuries, taking into account other important factors, and to examine the effect of tolerance, if any.

DESIGN

Prospective cohort study.

SETTING

University hospital and community hospital emergency departments and morgue.

PATIENTS

1362 Motor Vehicle Crash patients age >/=18, treated and released, admitted, and deceased.

MAIN OUTCOME MEASURES

Excess injury measured by Injury Severity Scale (ISS) 90, Weighted Revised Trauma Score (WRTS), and G-Score.

RESULTS

Using regression analysis, the best predictors of injury severity were vehicle crush (TAD), safety belt use, and their interaction, and age. Alcohol use further predicted injury. Using the final regression model, the effect of alcohol was to increase ISS90, on average, by about 30% (from a predicted ISS90 of 5.1 to 6.8, all else being equal). The adjusted odds ratio for serious injury (ISS90>15), was 1.59 for a patient with a positive blood alcohol concentration (alc+) compared to a alc- patient. This potentiating effect is seen even for patients with low levels of alcohol (<22 mmol/liter; <0.100 BAC) but is not linear with increasing alcohol level. Tolerance to alcohol did not affect the potentiation of injury by alcohol.

CONCLUSION

When other relevant variables are considered, alcohol increases injury, but the effects of alcohol level and alcohol tolerance are less clear. These findings have important implications for injury prevention, treatment, and research.