Tuesday, January 20, 2009

Evidence-based medicine, part 2: No evidence that parachutes help.

A while ago I wrote about evidence-based medicine, the discipline of relying on evidence when making treatment decisions. I wrote about its strengths, but also the risk of relying exclusively on evidence. Bottom line, as Mom always said, is "Use your HEAD, Rosebud." (Yes, she called me Rosebud at times like that.) For details see my earlier post.

I'm at conference in Boston right now, and I just saw a great spoof of this topic. In 2003, the highly respected BMJ (British Medical Journal) ran this article:

Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials

If you understand medical research you're already laughing. Others, consider this:

Objectives To determine whether parachutes are effective in preventing major trauma related to gravitational challenge.

Design Systematic review of randomised controlled trials.
The punch line is that in a controlled trial, some people receive the treatment (a parachute) and some don't. In this case, they'd all then jump out of a plane. NOT bloody likely that you'd get many people to participate in that one. But, if we're being rigorous, no excuses! The "investigators" have no choice but to conclude that "the effectiveness of parachutes has not been subjected to rigorous evaluation by using randomised controlled trials."

These are exactly the words used by the staunchest advocates of evidence-based medicine to put down treatments that have no such trials.

My conclusion: pay attention to your mother. Or mine. Think.

p.s. The investigators end with a recommendation that "the most radical protagonists of evidence based medicine" ... participate in a trial of whether parachutes work.


  1. This is one of my favorite topics. I think you're just trying to keep me around. Since I've now been up for some 40 hours you'll have to excuse me if I stumble a bit through this.

    The commentary that you present is always one that is used to shake things up a bit when people of science try to promote evidence-based medicine (EBM). Quite frankly it is a humorous way of highlighting that EBM does not fulfill all of our desires for being able to perfect something which is non-perfectible - the practice of medicine. But one thing should be noted. EBM does not preclude common sense (of course, as momma said -> common sense isn't common). For instance, giving antibiotics and providing surgical source control to treat patients with septic shock is listed as Level D evidence. Meaning, there is no randomized controlled trial supporting these therapies. Well, that doesn't mean that we don't support the implementation of these therapies. It is simply that no ethical physician scientist would ever withhold these therapies and therefore the trial cannot be performed. Thus the therapies will remain Level D evidence. It is common sense that we would provide these treatments to cure anyone with overwhelming bacterial infections.

    EBM is absolutely necessary. It is what is driving medicine out of the dark ages of blood letting into the age of modern science. How can we possibly understand if what we do actually works? It is surprising to note that things which seem like "common sense" can actually lead to bad medicine. For instance, decades of research by Dr. Shoemaker drove the idea that if we pushed the oxygen delivery of critically ill patients by increasing their cardiac output, hemoglobin, and oxygen intake, then they would do better. It seems very logical. Oxygen is good, right? Without going into the boring details... it took decades to realize that this concept did not pan out. And in subsequent research that implemented Computerized Clinical Decision Support it actually found that pushing O2 delivery to supranormal levels actually hurt patients. And what about blood transfusion? People have been giving blood transfusions liberally with the idea that sick patients must have a normal hemoglobin level to get better. Seems logical, right? Wrong. Patients do much worse when liberally transfused with blood as compared to restricting blood transfusions to those patients who fall below a critical level.

    My point being that common sense doesn't get you good medicine in and of itself. We need to invest in the science of medicine. Unfortunately that has its flaws. Mainly because medicine is a science of statistics. And like Mark Twain said... "There are lies, damned lies, and statistics". This is where we have the biggest problem. There is too much literature out there in medicine. Most of which very educated people cannot possibly interpret. Each and every article written must be critically reviewed for accuracy and validity of study design. There are too many articles printed whose conclusions are not correct, or whose data do not hold water because the study design is inappropriate.

    Dave, what EBM really needs is for there to be less journals and better professional critical peer review. The reality is that this won't happen because the careers of academicians like myself are tied directly to the number of articles published. "Publish or perish", a well known phrase in academics is true. In 2006, PubMed had over 623,000 citations. That's a lotta meatballs.


  2. Great to hear from you again, Joe!

    Do take a look at my earlier post on the subject (linked in today's post) if you can. And for extra fun you can look into my posts about statistics. Part of my game here is to figure out how patients (starting with #1 here) can be more learned and effective partners in this new model of "participatory medicine."

    > better professional critical peer review

    Wow. I could get behind that.

    Now go to sleep - happy, I hope.

  3. Burden Of Proof

    Upon information and belief, evidence-based medicine (EBM) is how health care providers practice medicine based on the efforts of evidence based researchers. These researchers consider EBM the apex for their approach as they conduct randomized controlled trials.
    The health care providers assess the risks and benefits of how they choose to treat or not to treat their patients. This paradigm of a practicing fully utilizing EBM allows the health care provide to better predict the clinical outcomes from the ideal treatment options concluded according to EBM.
    EBM implemented by health care providers recognize the need for improved quality in medicine. They also strive to place tremendous value on the restoration of the health of their patients- and they perceive the EBM approach to be the standard approach in their medical practices.
    It is believed that there are three areas of evidence-based medicine:
    1. Treat patients according to what is reasonable and necessary based on the evidence that exists regarding the treatment options health care providers select.
    2. Health care providers review this evidence in order to judge and assess the best treatment for their patients.
    3. Recognize that evidence-based medicine is in fact a movement that emphasizes the usefulness of this method to practice medicine.
    A standard of care is created as a result.
    It is also believed that there are two types of evidence-based medicine:
    1. Evidence-based guidelines- Policies and regulations are produced to ensure optimal health care.
    2. Evidence-based individual decision making- This is how restoring the health of others is practiced by the health care provider.
    While critics claim that EBM is too restrictive in practicing medicine and treating patients, EBM seems to be the preferred way to practice medicine instead of relying on possibly biased medical guidelines. Rather than EBM being restrictive, it is in fact potentially improved by enhancements such as electronic health records.
    Medical guidelines for a particular disease state are created from a combination of clinical studies in which conclusions are drawn to reflect national standards of care for a particular disease state. Guidelines were implemented during the 1980s as an alternative to relying on only EBM.
    At times, these guidelines are privately sponsored by those profitable medical industries that are able to gain profit depending on what such guidelines state about treatment considerations. This makes guidelines, at times, unreliable due to bias, as they are without independent systematic review or quality considerations by others.
    Unlike evidence-based medicine, guidelines can have major flaws and inaccuracies due to toxic factors such as commercial sponsorship received to create such guidelines. It is likely because of flaws such as this that most doctors do not follow medical guidelines, yet are rewarded and reimbursed by programs such as Medicare if they do follow medical guidelines that are established.

    Dan Abshear


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