Thursday, 7 June 2012

Are doctors as good as they think they are?


Benjamin Spock, the American paediatrician, once said: “Trust yourself. You know more than you think you do”. That may be good advice for patients, but the opposite holds for doctors. We know that doctors overestimate the effectiveness of their treatments (a major theme of this blog), but it turns out that there is also a gap between their perceived knowledge of medicine and their actual knowledge. If you ask doctors how competent they are on a particular medical topic or skill (a subjective assessment) and then sit them down and test them on the same topic or skill (an objective assessment), you find a significant and consistent pattern: doctors think they are a lot better than they actually are. And it appears that surgeons (here and here) are not excluded.

To be fair, the discrepancy seen in the medical profession is not much different to that seen in other areas (click here for the review article). It seems we can all fail to recognise our own biases, but in medicine those biases are shared almost to the point of being universal, and are reinforced by a willing patient population, ready to believe the next medical claim. This prevailing bias makes it easy for medical treatments to get the credit for benefits provided by such things as the placebo effect and the natural course of the illness.

A worrying finding from the review article was that the discrepancy was worse in poor performers and those with the most confidence.

Of course, this overestimation goes hand in hand with the general overestimation of benefit and underestimation of harm that this blog aims to highlight. I think we need a correction meter, like when your friend tells you how good their band is, or when your architect estimates the cost of your building project (in which case you can at least double the number). When a doctor tells us that an operation has a 95% chance of helping us, and a 1% complication rate, we need to apply the corrective factor to get the real success and complication rates. An obvious problem is that the factor would vary widely, depending on the procedure and the doctor’s claim. A bigger problem is that we as consumers have no desire to apply such a correction: it isn’t what we want to hear.

6 comments:

  1. Thanks for this, Dr. Skeptic. I think you're right - the tendency to overestimate benefit and underestimate harm is not unique to physicians.

    The difference, of course, is that when your friend tells you how good his band is or your architect gives you a lowball estimate on your building project costs, it's not going to kill you. More on this at: "Things Your Doctor May Not Know" at http://ethicalnag.org/2011/11/07/what-your-doctor-may-not-know/

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    1. Thanks again, CZ.
      I agree, and I recommend your link. I will go one step further by recommending a link to your 2011 post on why experts are often wrong and why we trust them: http://ethicalnag.org/2011/04/29/why-experts-wrong/ which includes coverage of the biases and logical errors that experts make. The point I want to reinforce, from my final line, is that patients often have the same biases. Put the doctors and patients together in the same room and you have a formula for more tests and more interventions being done. Until doctors (and patients) take a more scientific approach and start to recognise their biases, and recognise the potential harms, it will continue.

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  3. Don't agree totally! A good doctor communicates with the patient in such a way that the patient will reveal everything.

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    1. Thanks NJ,
      Yes, getting all the information from the patient is important, and the patient needs to trust the doctor and feel comfortable with him or her. But that will make them more likely to trust the recommendations that the doctor provides. Removing the bias from those recommendations is the difficulty.

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