Why do doctors sometimes ignore medical evidence?

We doctors like to think (or at least claim) that the treatments we recommend and give to our patients are ‘evidence-based’. I’ve lost count of the number of doctors I’ve spoken to who have bandied around this term as a justification for how they treat their patients. That’s all fine, but of course just saying something is ‘evidence-based’ does not make it so. Often, the rhetoric of this expression is not supported by the research.

There’s a good example of this this week in the latest edition of the Archives of Internal Medicine. It concerns the practice of ‘stenting’ – the insertion of a small, spring-like metal tube in a coronary artery in an effort to restore of maintain blood supply to the heart muscle. Stents can be inserted via a metal wire that is usually inserted into a major blood vessel in the groin and then threaded into the vessels around the heart.

Stents are often inserted after a heart attack (myocardial infarction), and the general view is that the sooner they are inserted, the better. Back in 2006 a study was published which showed that, as a rule, stents inserted more than 24 hours after a heart attacked produced no benefits for patients compared to usual care based around drug treatment. The following year, the American Heart Association and similar groups used this research as the basis for advice to doctors to desist from stenting patients more than 24 hours after a heart attack.

The lead author of the seminal 2006 study – Dr Judith Hochman – followed this up with an assessment of the impact of her research on doctors’ practice [2]. Analysis of almost 30,000 individuals admitted to almost 900 hospitals revealed that stenting rates appear to have been left untouched by Dr Hochman’s research and official guidelines.

One potential reason for doctors not to heed the advice is that they’re not aware of it or the research that underpins it. However, given the nature of their work, the chances of doctors missing this information are about the same as them missing a truck being driven through their living room.

Another potential explanation is that although they’re aware of the research, they decide to ignore it. But why would they do that? Once reason has to do with the fact that in the US, doctors are generally paid for specific tasks. The cost of stenting is about $20,000. I have no idea how much of that goes to the doctor performing the procedure, but I’d hazard a guess that it’s in the region of $5,000. The procedure usually takes 30-60 minutes. Forgive me if sound at all cynical, but the plain fact of the matter is that many doctors would find it hard to turn their back on this sort of earning potential.

A year or so ago, the son of a friend of mine was contemplating an operation on his hip. The surgeon he had seen privately (as a paying customer) was keen to proceed, but my friend was hesitant. As it happened, I knew a doctor acquainted with the surgeon in question. I phoned him to recommend someone for a second opinion. When I told him the surgeon’s name he commented that he was not surprised that surgery had been recommended. I asked why, and he replied that the surgeon is known as someone who recommends surgery to everyone, whether they need it or not. He added the surgeon is an example of a doctor who cares more about business than medicine.

I have no issue with people earning a living (even a good living). The issue here, though, is that the way doctors are remunerated can represent a conflict of interest that can compromise good medical care. I am not against private medicine per se, but my experience in it has led me to conclude that it can encourage the recommendation of investigations and treatments that are difficult to justify from a medical perspective.

Why do doctors ignore medical evidence and not do the right thing by their patients? Because, sometimes, it pays them to.


1. Hochman JS, et al. Occluded Artery Trial Investigators. Coronary intervention for persistent occlusion after myocardial infarction. N Engl J Med. 2006;355(23):2395-407.

2. Deyell MW, et al. Impact of National Clinical Guideline Recommendations for Revascularization of Persistently Occluded Infarct-Related Arteries on Clinical Practice in the United States. Arch Intern Med, 11 July 2011 [epub ahead of print]

4 Responses to Why do doctors sometimes ignore medical evidence?

  1. MikeS 15 July 2011 at 10:05 pm #

    Here’s an interesting article on the the second study referenced by Dr. Briffa. It’s from theheart.org, a website principally for physcians and researchers, but open to the public.


    To Dr. Briffa point about the pecuniary benefits to operate, the editorial accompanying the publication had this to say:

    “In addition, in a fee-for-service health system and in an environment in which more and more physicians are being compensated on the basis of relative value unit productivity, it remains to be determined whether personal financial gain might play a role in continuing old practices and in performing procedures shown to be of no benefit.”

  2. DanC 16 July 2011 at 6:26 am #

    Dr Judith Hochman’s 2006 results showing “stents inserted more than 24 hours after a heart attack produced no benefits” cannot be repeated. She knows that but now she pettishly seeks to show us no one listens to her. They ignore HER evidence.

  3. catherine 16 July 2011 at 8:07 am #

    Welcome to South Africa, your elective c-section-happy country. I know four women who have recently had babies, out of the four, ONE was a natural birth, the rest were elective caesars, one with a nip/tuck thrown in…

  4. kem 11 August 2011 at 7:35 pm #

    you might find this conversation interesting.


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