Use of alcohol as a risk factor for bicycling injury

Context Bicycling is one of the leading causes of recreational injuries. El evated blood alcohol concentrations (BACs) are found in about one third of fatally injured bicyclists aged 15 years or older. Objective To assess the relative risk of fatal and serious bicycling injury according to BAC. Design Matched case-control study. Setting and Subjects Bicyclists aged 15 years or older who were fatally or seriously injured while riding a bicycle during the day in Maryland in 1985 -1997 (cases, n=124) and bicyclists aged 15 years or older who were intervi ewed and given a breath test for estimated BAC during roadside surveys that took place in June 1996 through May 1998 at the same site, time of day, da y of week, and month of year in which a case bicyclist was injured (control s, n=342). Main Outcome Measure Odds ratio of bicycling injury according to estimated BAC. Results An estimated positive BAC (greater than or equal to0.02 g/dL) was d etected in 12.9% of the case bicyclists (23.5% of the 34 fatally injured an d 8.9% of the 90 seriously injured) compared with 2.9% of the control bicyc lists (P<.001). Relative to an estimated BAC of less than 0.02 g/dL, the ad justed odds ratio of bicycling injury was 5.6 (95% confidence interval [Cl] , 2.2-14.0) for a BAC of 0.02 g/dL or higher and was 20.2 (95% CI, 4.2-96.3 ) for a BAC of 0.08 g/dL or higher. Rates of helmet use at the time of inju ry or interview were 5% and 35%, respectively, for those with and without a positive BAC (P=.007). Conclusion Alcohol use while bicycle riding is associated with a substantia lly increased risk of fatal or serious injury.