How false positives can kill patients

I’ve written in the past that more medicine and tests do not necessarily reflect better care.

There is no test that is 100% specific or sensitive.  That means tests may be positive, when, in fact, there is no disease (“false positive”), or tests may be negative in the presence of disease (“false negative”).

It’s the latter that often gets the most media attention, often trumpeted as missed diagnoses, but false positives can be just as dangerous.

Consider this frightening case report from the Archives of Internal Medicine:

A 52-year-old woman presented to a community hospital with atypical chest pain. Her low-density lipoprotein cholesterol and high-sensitivity C-reactive protein levels were not elevated. She underwent cardiac computed tomography angiography, which showed both calcified and noncalcified coronary plaques in several locations. Her physicians subsequently performed coronary angiography, which was complicated by dissection of the left main coronary artery, requiring emergency coronary artery bypass graft surgery. Her subsequent clinical course was complicated, but eventually she required orthotropic heart transplantation for refractory heart failure. This case illustrates the hazards of the inappropriate use of cardiac computed tomography angiography in low-risk patients and emphasizes the need for restraint in applying this new technology to the evaluation of patients with atypical chest pain.

With the proliferation of CT scans that can detect coronary artery disease, there have been some who advocate more aggressive use of the tests. In the emergency room, for instance, a scan that can accurately detect heart disease would be a huge diagnostic leap forward.

But we’re not there yet.

As this case shows, there are real consequences to false positives. Often times, they lead to more invasive tests, like biopsies, or in this case, a cardiac catheterization that went horrifically awry.

So, if you or your doctor believe in getting a scan “just to be safe,” consider this case where such a mentality led to a heart transplant.

False positives can potentially kill.

 is an internal medicine physician and on the Board of Contributors at USA Today.  He is founder and editor of KevinMD.com, also on FacebookTwitterGoogle+, and LinkedIn.

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