wphamilton

I take issue with the boldly stated "In addition, the risk for a collision with a motor vehicle was significantly lower."

Drunk cyclists could have had higher incidents of crashing by themselves, which would lead to a lower proportion of injuries where motor vehicles were involved. In fact, that seems much more likely doesn't it? In that case it does not follow that the risk of collision was lower. Risk of other kinds of accidents was higher for drunks, so there were more of them relative to collisions.

You'd expect a more severe injury with a collision with a car than if you hit a sidewalk bump and fall over. So the drunks would have more of the less traumatic injuries relative to the number of more traumatic collision injuries. The authors failed to normalize the results against the type of accident, leading to the suspect conclusion that helmets didn't help them.

It also needs to be evaluated in context of conflicting results such as Use of Alcohol as a Risk Factor for Bicycling Injury, Guohua Li, MD, DrPH; Susan P. Baker, MPH; John E. Smialek, MD; Carl A. Soderstrom, MD which concluded: "Alcohol use while bicycle riding is associated with a substantially increased risk of fatal or serious injury." Why did Harada et. al find that there was no difference in injuries, when Gouhua and others find that there is a significant difference in injuries? In light of the logic fails above, I suspect that there are other problems in methodology and in analysis in the cited study.