Friday, August 17, 2012

The Over Diagnosis of Disease: How Medical Technology Can Endanger Your Health


Do you feel well?  If so, DO worry.  Emerging medical technology will soon fix that problem and cure you of your sense of well being.  Medical technology is advancing our ability to find more and more diseases.   Even if you feel well, advancing medical technology will soon find a disease with your name on it.  

It turns out that in a lot of people who think they are well, we can find pathological evidence of some disease process if we look hard enough.  And technology is improving our ability to look.  If you feel good, maybe we should just look harder and try to find something wrong.

This vision of medicine is not far fetched.  As a fascinating editorial in the Archives of Internal Medicine notes, this era is already upon us.  Authors Jerome Hoffman and Richelle Cooper write about how overdiagnosis of disease is becoming a modern epidemic.  It is created by medical technology and forced on an unsuspecting public that may not realized that more diagnosis can sometimes endanger their health.

The editorial notes another article in the Archives that described how better imaging technology is advancing our ability to diagnose pulmonary embolisms.  Pulmonary embolisms are blood clots that form in the lungs.  Previous technology tended to identify big embolisms that we knew to be life threatening.  But newer CT technology is identifying smaller embolisms.  But patients with small embolisms are treated with blood thinners in the same manner as patients with big embolisms.  It is not clear whether treating smaller and smaller embolisms will reduce mortality. 

We have previously discussed on GeriPal how this same issue may lead to overdiagnosis of Alzheimers disease.  Improving imaging and biomarker technologies can identify the pathologic changes of Alzheimers Disease decades before a person has any symptoms of dementia.  This can be good if treatments can prevent dementia. There is a big problem though.  Many of the persons with these pathologic changes will never have symptoms of Alzheimer’s disease.  They have pathology that is meaningless to them.  Yet, our new technologies risk subjecting them to treatments with possibly harmful side effects.

The problem is that better methods of diagnosis, such as advanced imaging techniques, is that they identify insignificant "diseases" that would have never been identified by old fashioned diagnostic methods.  The “pathologies” detected meet all standard definitions of diseases.  However, it turns out maybe it was actually good our old diagnostic technologies failed to identify these “diseases.” It turns out that these difficult to diagnose diseases may actually have little impact on the patient.  The patient feels no symptoms, and in many cases, if the diseases are not diagnosed, nothing bad will happen.

This actually turns what we learned about diagnostic testing in medical school on its head.  We learned that a diagnostic test can be either right or wrong.  We learned about these 4 outcomes of diagnostic testing:

  • 1       It can identify disease in someone has the disease (true positive)
  • 2       It can identify disease in someone who does not have disease (false positive)
  • 3       It can find no disease in someone who actually has disease (false negative)
  • 4       It can find no disease in someone who actually has no disease (true negative)
When we learned about these possibilities, the assumption was that the “truthful” outcomes were good, and the “false” outcomes were bad. 

We never considered the possibility that a test can accurately identify disease in a patient with a disease that does not matter.  We never learned about the blessed possibility that a test can fail to identify a disease in a patient who is better off not knowing about their meaningless "disease."

Maybe we need to change our definition of disease.  A disease should really be defined as a pathologic state that will lead to bad health outcomes in a patient.  Abnormal pathology that leads to no ill effects should not be defined as a disease.  Everything we know about diagnostic testing really needs to be reconfigured to account for this patient centered definition of disease. 

 
by: Ken Covinsky

3 comments:

Anonymous said...

thanks for sharing.

Anonymous said...

Ken, thanks for your superb commentary! I agree with your perspective and think that we doctors should be more cognizant of over-diagnosing. Your comments remind me of something one of my previous mentors (Dr. Alvan Feinstein) would have written or said. -sm

Catherine Hepburn said...

It seems most medical technologies these days overlook the old adage, "too much of a good thing is bad". While procedures have gotten so advanced that they've managed to detect "anomalies" that would've remained invisible twenty years ago, they might actually go as far as attack and neutralize some parts of those "anomalies" that might actually be beneficial to the body.