Reply to Why are there no safety rules regarding children on bikes?

Forum Index » Metropolitan DC Local Politics

Reply to "Why are there no safety rules regarding children on bikes?"

Subject:

Emoticons





More smilies

Text Color: Font: Close Marks

[quote=Anonymous][quote=Anonymous]These people from some outfit called the CDC seem to think helmets are pretty important.

"An average of 247 traumatic brain injury deaths and 140,000 head injuries among children and adolescents younger than 20 years were related to bicycle crashes each year in the United States. As many as 184 deaths and 116,000 head injuries might have been prevented annually if these riders had worn helmets. An additional 19,000 mouth and chin injuries were treated each year."

https://pubmed.ncbi.nlm.nih.gov/8909479/[/quote]

The authors of this article didn't do any research. They just cited previous research that shows that helmets are 75% effective in preventing injury and death, and counted the number of injuries and deaths per year, subtracted out the current level of helmet usage and calculated what that would be if helmet usage were 100%. They accept the 75% effectiveness number unquestioningly.*

For the 75% figure they cite the 1989 Thompson, Rivers and Thompson study. If you do any work at all in this field you're familiar with this study, all of the inflated claims of helmet effectiveness can be traced back to this study. This study has been debunked; when other researchers tried to replicate it they were unable to reproduce the results, which is a foundational principle of the scientific method.

There is a federal law called the Data Quality Act, which requires that if federal agencies make scientific claims in their public statements that those claims be backed up by peer-reviewed science. In 2013 -- after this study was published -- a complaint was filed with the CDC and the NHTSA that research that relied upon the 1989 Thompson, Rivers and Thompson study violated the Data Quality Act and should not be promoted on a taxpayer-supported website. The CDC and NHTSA both initially resisted, but ultimately upheld the complaint and agreed to remove all affected research. Clearly they either didn't catch it all or have backslid since then.

You can read more here: 
https://www.thewashcycle.com/2013/06/nhtsa-admits-helmet-effectiveness-claim-violates-data-quality-act.html

The best comprehensive study of the effectiveness of helmets was published in 2011 by Rune Elvik in the journal "Accident Analysis and Prevention" ( available at http://www.cycle-helmets.com/Elvik2011_helmet_reanalysis.pdf . His conclusion:
[quote]
When the risk of injury to
head, face or neck is viewed as a whole, bicycle helmets do provide
a small protective effect. This effect is evident only in older studies.
New studies, summarised by a random-effects model of analysis,
indicate no net protective effect.[/quote]

There are many theories as to why the measures of the effectiveness of helmets have declined over the past thirty years. There is a well-known scientific phenomenon that as the true value of a figure being measured becomes better known, the published estimates become closer and closer to the actual value, because numbers too far from the range of what reviewers expect don't get published. In the case of bicycle helmets in particular I believe that better record-keeping over the past 30 years is a major factor. Many studies rely upon case reports by the doctor who treated the patient, and it turns out that often by the time the doctor sees the patient the EMT's have removed the helmet and the doctor doesn't know if the patient was wearing a helmet. It was only once this research started being published that people started caring about accurately recording whether the patient had been wearing a helmet.

Elvik thinks that newer helmets are thinner and less effective than older ones, but I'm skeptical. The CPSC standard hasn't changed.

*(As an aside, I can't believe adults get paid to produce "research" of this quality.)[/quote]

Options

	Disable HTML in this message
	Disable BB Code in this message
	Disable smilies in this message

Review message

Search Recent Topics Hottest Topics