Thursday, February 4, 2010

Of gatekeepers and unbridled imaging technologies

When I was a third-year medical student on my Surgery rotation at Bellevue Hospital in New York City, more than a decade ago, the assignment I dreaded most - more than "scut work" such as drawing blood samples or removing stitches - was going to the Radiology department to present clinical cases to the attending physician for permission to use the hospital's one and only CT (computed tomography) scanner. I learned to put together meticulously reasoned arguments about why images created by this precious piece of equipment were absolutely necessary to obtain a diagnosis that couldn't be made with an examination, blood tests, or ordinary x-rays. The attending's job was to be a gatekeeper - to make sure that the costly scanner was utilized only for high-priority diagnostic dilemmas. More often than not, that meant tearing the unlucky medical student's case to shreds.

Fast forward five years. I'm working in a private primary care practice in Arlington, Virginia, and can order imaging tests simply by checking off blanks in a form and scribbling a general symptom such as "headaches" or "abdominal pain." A patient of one of my colleagues who is on maternity leave presents to the office with vague pelvic pain and becomes incensed when the soonest I can schedule her for an ultrasound at the local hospital is in two weeks. She takes my prescription to a different radiology center and is scanned the next day for what turns out to be a large but benign ovarian cyst. By the time the report is delivered to my office, she has already had surgery to remove the cyst and tells me that she doubts she'll ever visit my practice again. In a city when 24 hour imaging services are available for the right price (or insurance), a two week wait is apparently grounds for malpractice.

Fast forward to the present day. I rarely see patients, yet receive phone calls every few weeks at my non-clinical office from for-profit imaging companies letting me know that there are spots open on the schedule for their MRI machine, in case I happen to see a patient that day "with an indication" (read: any patient with a symptom that I can't completely explain). An editorial in the Annals of Internal Medicine complains that CT colonography ("virtual colonoscopy") has been held to an unfair standard as a screening test for colon cancer, even though it's significantly more expensive than other tests and exposes patients to large doses of radiation.

In Ontario, Canada, the average waiting time for a non-emergency CT scan is 42 days, and for an MRI, 107 days. Opponents of single-payer health systems cite these kinds of statistics as proof of the superiority of American health care. But there are downsides to the widespread availability of imaging services in the U.S., in addition to the high costs of maintaining the technology. In some situations, such as ultrasonography for asymptomatic carotid artery disease or MRI for low back pain, imaging can cause more harm than good, by leading to unnecessary surgical procedures. And the tests themselves aren't harmless, either - recent studies have estimated that the radiation from 72 million CT scans performed in 2007 has led to thousands of cancers that wouldn't otherwise have occured.

So maybe it's time to bring back the gatekeepers, albeit in less intimidating guises. Barring that, you or I could choose to move to Canada, where they wait longer to get CT scans, but spend half as much money on health care, live 3-5 years longer, and report better emotional, physical, and mental health than do Americans.