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False Positives In Medical Tests: How They Can Kill Patients

January 3rd, 2011 by KevinMD in Better Health Network, Research

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

There is no test that is 100 percent 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.

*This blog post was originally published at KevinMD.com*

Tags: Absence of Disease, Accuracy in Diagnosis, Archives of Internal Medicine, Diagnosis and treatment, Diagnosis Error, Dr. Kevin Pho, False Negatives, False Positives, General Medicine, Incorrect Diagnosis, KevinMD, Medical Diagnosis, Medical Diagnostics, Medical Malpractice, Misdiagnosis, Overtesting, Patient Death, Presence of Disease, Preventable Death, Too Many Medical Tests, Too Much Testing, Unnecessary Medical Tests, Wrong Diagnosis