Why we doctors order far too many scans

There’s a provocative editorial in a recent New England Journal of Medicine about the explosive rise in high-tech medical imaging. Everyone knows doctors order a lot of CT scans, MRI scans, and ultrasound studies, and that the number of these has been steadily increasing. And the cost is enormous. From the article: ” . . . these costs were the fastest-growing physician-directed expenditures in the Medicare program, far outstripping general medical inflation.”

To be fair, rising use of new medical technology is expected because, well, it’s new. What is unclear is that how much of this increased use has led to improved health to justify the cost. Clearly much of it doesn’t, and unnecessary scans, particularly CT scans, lead to risk with no benefit.

The practice of “defensive medicine,” of doctors ordering tests out of a fear of being sued for missing rare conditions, is often given as a cause for overuse of scans. There is some truth to that: the article cites a Massachusetts study showing that 28% of scans are done for that reason. Lawsuits over failing to diagnose things are common; lawsuits about overuse of tests are vanishingly rare.

Physician conflict-of-interest also plays a part. Through a loophole in Medicare regulations, physicians are allowed to refer patients for scans from which the physician benefits financially. That is wrong and needs to be fixed.

But there are deeper reasons. The root cause may well be “the style and content of clinical education and their impact on medical practice.” In other words, how doctors are trained. We use scans unthinkingly, and, unthinkingly, can cause harm. Again from the editorial: “The greatest risk that patients face with unnecessary imaging is the needless exposure to downstream testing and inappropriate treatment related to misdiagnosis and the overdiagnosis of common but unimportant findings.” I’ve seen that happen more than a few times.