Monday, May 1, 2017

Every screening test is a calculated gamble

When I was last in Las Vegas to attend the International Consumer Electronics Show, I stayed at one of the city's many combination hotel and casinos, with a layout designed to funnel guests and other visitors through the gaming floor to get practically anywhere. While walking past a row of pulsating slot machines in the lobby one morning, I remembered the title of a terrific New York Times editorial I read a few years ago, "You Have to Gamble On Your Health."

Courtesy of www.lasvegas.com

In this editorial, Dr. H. Gilbert Welch (whom I've lauded before for his work on the subject of overdiagnosis) explained why even though most people who receive screening tests for cancer think that they are playing it safe, every test has tradeoffs. Just as a gambler rarely hits the jackpot in Vegas, a patient who undergoes cancer screening is rarely the lucky one whose life is extended from the test, and much more likely to figuratively lose his or her shirt. Common harms of screening include false positive results, risks associated with subsequent diagnostic procedures, and possible unnecessary treatment (and associated side effects) for "cancer" that looks dangerous under the microscope but is actually destined to never cause health problems.

Courtesy of www.lasvegas.com

The good news is that for a few very well-studied screening tests such as mammography, an informed patient can assess the odds of all of these outcomes based on scientific data and decide whether screening is a better choice for her than no screening. A mammography screening decision aid by Dr. Jill Jin that appeared in JAMA did a great job of illustrating these tradeoffs, and may help to explain why one prominent health journalist announced that she had decided to forego mammography because she believed that "the numbers are in my favor."

Yes, every screening test is a gamble, but I give credit to my fellow physicians for providing increasingly sophisticated support for these tough decisions that you'd never get in Vegas.

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This post first appeared on Common Sense Family Doctor on January 6, 2015.

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