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COST: Weighing in on the Value of CT Scans

Sunday's New York Times's article, the first in a series on evidence-based medicine, got me thinking about how we set standards for the practice of medicine, and what it will take to get doctors to follow voluntary ones.

The extensive front-page article examed the prevalence and value of computed tomography (CT) angiography. In brief, CT scanners can generate a complete image of the heart (see NBC's Matt Lauer's here and Oprah Winfrey’s here).The technology is impressive. So is the price. A CT scanner costs about $1 million. Doctors and hospitals that make the investment have a large incentive to recoup their costs by ordering CT scans, ($500-$1,500 a test). In some specific circumstances, CT angiography provides more information than other heart studies. The Times noted certain situations in an emergency room where it could be highly useful. But in most circumstances it is more like a screening tool to search for hardening of the arteries. But the CT scan doesn't say whether someone needs the blockages opened. That has to be determined by coronary angiography, placing a catheter through a vessel in the groin and then threading it up to the heart. That's an invasive procedure that provides necessary details on the exact location and extent of blockages.

The question raised in this article is, "What is the value of CT angiography of the heart as screening tool for heart disease?" How many people have no symptoms of heart disease but have some risk of developing it? Almost any adult. With the possibilities for using the imaging technology virtually unlimited, how do we set limits? Don't assume Medicare will. As the Times noted, Medicare did say last year that it wanted more evidence before paying for these scans, but backed off after extensive lobbying of the agency and Congress by cardiology groups.

Some of the cardiologists in the Times article describe detecting lesions that they otherwise might not have discovered; others, more critical of the spreading technology, countered that they hae other tools to monitor and diagnose their patients. The American College of Cardiology has established some general guidelines for the use of CT angiography of the heart based upon the limited information that is available. The use of CT angiography to detect heart disease in patients with low risk for heart disease is considered "inappropriate". Its use to detect heart disease in patients without symptoms who are at high risk (such as those with high cholesterol and a family history) is of "uncertain" value.

One risk of this procedure is that the level of radiation delivered has a cumulative effect on a patient's risk of cancer. Another is that it can give either false positive or false negative results leading to either unnecessary additional procedures or a potentially dangerous sense of false security. Therefore, the American College of Cardiology considers its use "appropriate" under only very specific circumstances.

These and other guidelines like them are issued by organizations, but an individual doctor's adherence to them is neither measured nor reported. Such guidelines, therefore, have almost no impact on medical practice and pretty clearly have not influenced the debate over the use of this technology.

Not surprisingly, the article generated a rash of responses almost all of them decidedly critical of the current environment in which CT scans are used. The Health Care Blog picked up on an especially interesting section of the article, in which a Dr. Harvey Hetch responded to criticism of his decision to order a CT angiography saying: "it's incumbent on the community to dispense with the need for evidence-based medicine. Thousands of people are dying unnecessarily."

The irony of Dr. Hecht's words is that the opposite is more likely true. I would say that the lack of measured and reported standards of medical practice kills people. The adherence to evidence-based standards of practice could saves lives and a lot of money.

As it is now, a patient that goes to a doctor has only about a 55 percent chance of receiving treatments that are the standard of care.

We in medicine must know what care our patients need -- and then we must provide it. We shuld not provide unneeded care. Thinking about coronary CT scans, and medical innovation in general, raises the following issues:

  1. What is the relative weight of risk to benefit of new technology in specific patient groups?
  2. Since no agency or company is required to determine the value of new technology, only its safety, who should do it?
  3. Doctors can use new technology as they wish, even if they profit from ownership of the equipment. Should use of new technology be restricted to circumstances in which its benefit is proven?
  4. If there were reliable standards for the use of technology such as CT angiography, who will measure the pattern of a doctor's practice to determine if he or she is practicing mostly within standards or far outside of them?

As a neurosurgeon, I do not want to impede the development of new technology. I have seen what technological breakthroughs have done for patients. But appropriate assessment and use are not impediments. They serve to protect the public.