English summary: Cycling under the influence of alcohol increases the risk of head injuries

Background

Most of the bicycle accidents that occur are not included in the official traffic accident statistics reported by the police. Further, little is known about the bicycle accidents and their consequences occurring when the cyclist is under the influence of alcohol.

Methods

Data on patients attending the emergency department (ED) at North-Kymi Hospital due to a bicycle accident were gathered prospectively for two years. Breath alcohol concentration (BAC) was measured on admission. The special focus of the present study was on alcohol-related bicycle accidents.

Results

A total of 217 bicycle accidents occurred. One third (67/217; 30%) of the injured cyclists were under the influence of alcohol at the time of hospital attendance. The alcohol concentration was ≥1.2‰ (≥0.12% BAC) in nearly 90% of the alcohol-positive cases. A positive BAC was more frequent among male than female cyclists (44% vs. 12%) (p<0.001).

There were more head injuries in alcohol related accidents (60%) than in those where the cyclist was sober (29%) (p<0.001). Two thirds (64%) of the cyclists who were cycling under the influence of alcohol were not wearing a bicycle helmet, and they injured themselves mostly in accidents occurring without any other party. Alcohol-related accidents occurred more often at weekends than those where the cyclist was sober (p<0.001). The proportion of severe injuries (MAIS≥3) was equal in both groups. Risk factors for head injuries were cycling under the influence of alcohol (BAC more than 1.5‰ (≥0.15% BAC); OR 6.71; 95% CI 3.37-13.34), age 15-34 years (OR 3.25; 95% CI 1.70-6.21) and cycling without wearing a bicycle helmet (OR 1.92; 95% CI 1.09-2.89).

Conclusions

Cyclists who injured themselves under the influence of alcohol were usually heavily intoxicated and in most cases they were not wearing a bicycle helmet. They sustained head injuries more often than those who were sober. Alcohol was the most important risk factor for head injury. Alcohol-related accidents occurred mostly without involvement of another party.