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October 7, 2013

Patients’ Diagnostic Accuracy is Better than Physicians!

Perhaps a controversial headline but a study recently appeared in JAMA (Journal of the American Medical Association) ‘Physicians' diagnostic accuracy, confidence and resource requests which revealed some rather shocking figures about the levels of physicians’ diagnostic accuracy, confidence and the contribution to diagnostic accuracy made by lab tests and imaging.

  • The study is brilliant and the authors are to be congratulated. However, the results, which show a diagnostic accuracy rate of 55% for the easy cases and just 6% for the hard cases, are truly shocking and the authors’ statement that  "overall diagnostic accuracy was rather low- 31% across the 4 cases” must be the understatement of the year!
  • The cases used for this study are known to be quite difficult so one could excuse a low level of accuracy if the physicians weren’t so confident that they were right. The study looked at how confident the physicians were in their diagnoses and what was also shocking was how little their level of confidence changed from the easy to hard ones. For the easy cases it was 7.2 out of 10 and for the hard cases it was 6.4 out of 10. So, even with an accuracy rate of only 6% for the hard cases, the physicians were still 64% confident that they were right! The issue here from the patient’s perspective is they can put up with 6% accuracy if they know that the person is only say 10% confident of being right as they know where they stand but if it’s a respected professional who appears confident this can be very dangerous. With the high confidence and low accuracy the patient has the illusion that he’s being reasonably well looked after.
  •  The study also looked at the accuracy at 4 different chronological stages in the diagnostic process:
  1. Chief complaint and medical history
  2. Physical examination
  3. General laboratory and imaging
  4. Definitive or specialized laboratory and imaging.
What is alarming is that the accuracy of diagnosis appears to have been barely improved after the history and physical stages with the labs and imaging, begging the question what is the point of all that expensive testing? Perhaps this shouldn’t be a surprise when one of the old adages in medicine is that 75-80% of the diagnosis is revealed by the patient’s story. The lab tests should just be used to confirm a suspected diagnosis but not as a scattergun approach that hopefully reveals the answer.
  • Lack of time did NOT seem to be an issue in the low levels of accuracy, although physicians often cite this as a problem. It seems that the high levels of confidence meant that the physicians did not request additional resources. Rather than the term 'over confidence' a more apt explanation may be the 'illusion of knowledge'; the over confidence resulting from the illusion of knowledge. My personal view is that often a lack of time is simply an excuse not to do something which is either not perceived as sufficiently important or where the person believes they know what they need to already. 
  • The 31% overall rate of physician accuracy could be compared to results from a Pew Survey written up in a previous blog which showed that 41% of patients ‘own diagnoses were confirmed by their physicians! This is clearly taking both studies out of context but the point to emphasise is that physicians' diagnostic accuracy is far less than they would like to believe and that patients’ diagnostic accuracy is far better than physicians tend to assume. This is a perfect argument for the two groups to work together as a team towards a jointly created differential diagnosis.
  • One of the solutions suggested in the study is  "engaging patients in creative ways". One could be actively encouraging patients to use a sophisticated symptom checker, like Isabel, before the consultation so that they could contribute more productively. With the Isabel symptom checker integrated into a patient portal, the patient could enter their details before the consultation which could then be available through the institution’s EMR system so that when the patient presented the physician could bring it up on his computer and discuss it with the patient.Technology is the driving force behind patient engagement which allows patients to become more involved and more proactive in managing their healthcare outcomes.  Patient engagement tools like symptom checkers, drug databases and medical calculators provide instant access to health information and ensure patients become active participants in their healthcare.        
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Jason Maude

Jason Maude

Jason is the CEO and Co-founder of Isabel. Prior to co-founding Isabel, Jason spent 12 years working in finance and investment banking across Europe. His daughter, Isabel, fell seriously ill following a misdiagnosis in 1999 and this experience inspired Jason to abandon his city career and create Isabel Healthcare Ltd.


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