Open Letter to Dr. Crocker

August 10th, 2006

To: Austin City Council Members , Toby Futrell, City
Manager , Rudy Garza, Assistant City Manager , Mike McDonald, Assistant City Manager

Re: Bicycle Helmets and Injury Prevention

Dear Mayor Wynn and Council Members,

As you may know a part of our activities as a certified Trauma Center have been centered on injury prevention initiatives. One particular area of interest has become the prevention of disabling head injuries, especially for recreational bicyclists¹. Of note, a recent review of our trauma registry reveals that only 5% of patients under the age of 17 years were helmeted at the time of the bicycle accident.² 5%!! Of the 39 children and young adults³ with injuries serious enough to be transported to the Trauma Center and admitted for care, 46% sustained head and brain injuries³. In the significant majority of cases these injuries were life altering events with risk of long term disability.

Most interestingly, during this study period no patient in this age range who was helmeted suffered a serious head injury. NO PATIENT WHO WAS HELMETED SUFFERED A SERIOUS HEAD INJURY!⁴ Read that line again.

As a physician involved in the care of trauma patients for now more than twenty years as Chief of Emergency Medicine, at Brackenridge and Children’s Medical Center, I have witnessed countless lives needlessly altered by preventable trauma. This is one area where a helmet law could provide a significant safety factor for our children.⁵ Accidents aren’t predictable. You don’t need to be going either fast or far toneed protection against head injury. My best advice to patients is to buy a helmet, and then wear it, EVERY time you are on your bike.

Sincerely,

Dr. Patrick J. Crocker, FACEP

Chief, Emergency Medicine

Brackenridge and Children’s Hospital of Austin

Commentary on this email:

¹ From the beginning, Crocker reveals a lack of familiarity with this issue, as most serious recreational bicyclists (mountain bikers and road racers) already use bicycle helmets. The ACA, for example, requires the use of a bicycle helmet for allrides already. The group that would be most affected by a mandatory bicycle helmet ordinance are transportation bicyclists, and the biggest effect would be to dramatically reduce the number of people who use bicycles for transportation. The only proven statistically significant impact of MHL’s has been to reduce the number of bicyclists in places that implement them, in some cases by as much as 44% [ref, ref].

So why does Crocker focus on recreational bicycling when an MHL in Austin would be squarely aimed at transportation bicyclists? Perhaps it never occurred to Crocker that some people actually use a bicycle for basic transportation!

² Is Crocker trying to shock us with how few juveniles are actually wearing bicycle helmets or is he implying that those who do wear bicycle helmets are not showing up in the emergency room?

If the former, then one must wonder just how out of touch Crocker is, as Austin already has a juvenile mandatory bicycle helmet law. If juveniles are not wearing helmets, then clearly the existing law is not effective. Surely Crocker can’t be saying "The mandatory helmet law is not working. We need a mandatory helmet law to solve this problem!" That would be pretty dumb.

So, let’s assume that Crocker is implying that juveniles wearing bicycle helmets simply don’t appear in the emergency room, presumably because their helmet protected them from serious injury. Well, then—onward through the fog.

³ Now things are starting to get just a bit confusing. Is Crocker saying that the total number of all children and young adults "with injuries serious enough to be transported to the Trauma Center" over some unspecified period of time (1 year? 2 years? 5 years?) is 39, or is he referring only to children who had bicycle accidents? Since talking about all traumatic injuries seems rather irrelevant, and since we already know that only 3% of all head injuries are caused by bicycle accidents [ref],
I think we can safely assume that Crocker is restricting his comments to children who suffered an accident while riding a bicycle.



OK, then let’s start crunching some numbers. Earlier (²), Crocker informed us that only 5% of these kids were wearing bicycle helmets. 5% of 39 is …… 2. Crocker’s total sample size of helmeted juvenile bicyclists appearing in the trauma ward is 2. Remember this number for later.

⁴ Well, that certainly settles
the issue of how effective helmets are at preventing serious head injury!
Or maybe not? Recall that only 2 juvenile bicyclists of the 39 injured
were wearing helmets, and slightly less than half suffered head injuries.
Even if bicycle helmets are 0.0% effective at preventing head injuries, there
is a 29% probability that neither had head injuries simply by chance.



However, that’s neither here nor there. The data I want to focus on is the
100%-46% = 54% of juveniles who didn’t suffer a traumatic head injury.
These are the kids who suffered a broken leg or a broken arm, for example.
Observe that of these 21 children, only 2 were wearing bicycle helmets.

Conclusion: according to
Dr. Crocker’s "data," bicycle helmets are 90% effective at preventing leg
injuries and broken arms!!

⁵That’s right, folks.
The chief of emergency medicine at Brackenridge hospital, Dr. Patrick J.
Crocker, D.O., sent an email to city council inadvertently implying that
bicycle helmets are over 90% effective at preventing juveniles from
suffering a broken leg*, and that’s why Austin needs a mandatory bicycle
helmet law for adults, by golly. As is often the case, one would
be hard pressed to make up anything more absurd than this.

Follow Up:

It was never our intention to publicly embarrass Crocker with his own
misinformation. Before even considering publishing this letter, we asked
Crocker to either clarify or retract his comments. The text of Crocker’s response appears
below:

August 23, 2006

Hi —.

This request already finds me at home as since
I work weekends I usually take Wed afternoon off. I am
unable at this late date and time (Wed 8/23 at 5:37PM)
to provide you with detailed answers to your
questions. I would also caution as I did
in the letter to council this trauma registry review was not
intended to provided publishable type data, rather
simple frequency data, and to some degree severity
data. The data were based on the most recent calendar
years data from the trauma service at Brackenridge
Hospital. I will be presenting the 17 yo and over data
at the council meeting tomm. After over twenty years
as chief of Emergency Medicine at Brackenridge and
Children’s Hospitals I believe helmets save lives,
just as seat belts do, but you have to wear them to
reap the benefits. I also believe as you do that other
bicycle safety training can reduce injuries and
training is highly desireable.

We invite the reader to identify where in the original letter to
city council Crocker explains that his information was not intended to
be "publishable" — unfortunately, we can’t find it. Further, Crocker did
not appear at the August 28, 2006 public hearing to clarify his comments,
as promised. What Crocker has done is
persist in helping Bruce Todd and Elizabeth Christian in their efforts
to criminalize bicycling in Austin, most recently by proposing a case control study which will result in the collection of information
similar to what he has already provided in his email to city council.
As mentioned previously,
case control studies suffer from serious methodological flaws and have been
widely discredited in the literature. Crocker and his cohort,
Steve Berkowitz, are a good 20 years behind the times.

Our letter to Dr. Crocker was intended
to be a gentle suggestion that he’s in way over his head on this issue, and
should study the literature and talk to some actual bicyclists before
proceeding.

With the endorsement of most members of the Austin City Council,
the Department of Public Works, the Urban Transportation Commission,
the Austin Cycling Association, the Texas Bicycle Coalition,
and the League of Bicycling Voters,
a Bicycle Safety Task Force was proposed which Crocker and other
members of the medical community were invited to participate in.

Rather than work within the framework of the safety task force, however,
Crocker chose
to join Bruce Todd in making an end run around the task force concept, using
his position to endorse a study almost guaranteed to produce misleading and
inaccurate information, the only purpose of which would be to strong-arm
city council into passing an adult bicycle helmet law. From this, one can
only conclude that Crocker and Todd couldn’t care less about promoting
bicycling safety and are really only interested in promoting their own
narrowly defined political agenda for reasons that are their own. Bruce Todd is a lobbyist, who most recently tried to brow-beat the county into privatizing property tax collection,
a move which would have cost Travis county taxpayers millions
of dollars a year while dismantling a county agency that is 99% efficient
at revenue collection. In short, we can count on Todd to do anything that will
either make him money and/or increase his stature as a mover and shaker.
Crocker, however, is a physician. By promoting a measure which will likely
decrease, not increase, the safety of bicyclists, Crocker is in clear violation
of the Hippocratic oath.

We urge Dr. Crocker to reconsider his actions with regard to this
issue and invite him to work with the community to create a truly safe
environment for pedestrians and bicyclists. We strongly agree that we
should focus on injury prevention initiatives such as safety education
and training — for both bicyclists and motorists,
safer roads and bicycle lanes, and, above all, promoting bicycling
as a safe, healthy, and community-friendly activity.

* The mathematically astute reader will
observe that the author of this analysis has himself made a mathematical
error by not taking into consideration the percentage of juvenile bicyclists
who actually use a bicycle helmet. Statisticians would refer to this as the
underlying population distribution, and it is one of the factors frequently
overlooked in case study analyses of the effectiveness of bicycle helmets.
This information is required in order to
actually make the assertion that "bicycle helmets are 90% effective at
preventing broken legs", for example, since the 2/21 computation assumes equal
numbers of helmeted and unhelmeted juvenile bicyclists. Let me illustrate
why this information is critical by way of an example:
suppose we ascertain that only 2 out of every 100 bicyclists admitted to a
trauma center suffering a severe head injury were wearing a helmet at the time
of the accident. From only this information, it would appear that helmets
are extremely effective at preventing head injuries; however, if only 1 out of every 100 bicyclists in the population ever wears a helmet, then the data actually indicates bicycle helmets double the likelihood of a serious head injury!

Getting back to the percentage of
juvenile bicyclists in Austin who wear a helmet: Unfortunately, a
good estimate of this number is not known, but, given that Austin has a
juvenile mandatory bicycle helmet law in place,
it’s a reasonable assumption that
the number of juveniles using bicycle helmets is 50% or greater. The
larger the percentage, the more ridiculous the numbers get. For example, if
75% of all juvenile bicyclists wear a bicycle helmet, then Crocker’s claim is
that bicycle helmets are 96.5% effective at preventing broken legs. Again,
not paying careful attention to the underlying population
distribution is precisely the kind of mistake that the "case study" helmet
zealots make all the time. The proposed Crocker/Berkowitz study makes no attempt to
even consider the underlying population distribution, hence is completely
invalid from a statistical perspective. Oh, and I exaggerated a bit.
Even given the assumption of a 50-50 helmet/no-helmet population distribution,
Crocker is only implying that bicycle helmets are 89.47% effective at
preventing broken legs. Since Crocker rounded up, I did, too.

This page was written by
Patrick Goetz. Any and all mistakes are the sole responsibility
of the author. Last edited 27-Oct-2006