We are facing an epidemic in this country, a threat to our health caused not by pathogens, environmental toxins or lousy diets but by medical tests. Over the past couple of years, we've learned that two popular tests for cancer—mammograms and the PSA (prostate-specific antigen) test for prostate cancer—are less than useless for many people. Men are 47 times more likely to get unnecessary, harmful treatments—biopsies, surgery, radiation, chemotherapy—as a result of receiving a positive PSA test than they are to have their lives extended, according to a major European study. The ratio for women undergoing mammograms is between 6 and 33 to one, according to a new analysis by researchers at Dartmouth.

Now Gina Kolata, who has been diligently tracking debates over medical testing for The New York Times, reports on a recent study in which 31 professional baseball pitchers were scanned with magnetic resonance imaging. The study revealed that 28 of the pitchers had abnormal shoulder cartilage and 27 had abnormal rotator cuff tendons. Here's the problem: all of the pitchers were perfectly healthy, throwing without any pain. This and other studies, Kolata asserts, show that MRI scans "are easily misinterpreted and can result in misdiagnoses leading to unnecessary or even harmful treatments." I suspect that critical evaluations of many other medical tests would yield similar conclusions.

Several years ago, I got first-hand experience of just how test-crazy modern medicine has become. My teenage son Mac mentioned during a routine checkup that he occasionally heard a weird buzzing noise. Mac's pediatrician couldn't find anything wrong with him, but she told me that tinnitus, or ringing in the ears, is sometimes caused by tumors on the auditory nerve. This possibility was highly unlikely, she assured me, but just to be sure, Mac should have an MRI scan.

The radiologist who carried out the MRI said Mac's brain looked fine, but a tiny fuzzy spot in his inner ear could indicate fraying of the insulation of the auditory. This possibility was highly unlikely, he added, but just to be sure, Mac should see a neurologist. The neurologist said the MRI spot was insignificant, and his tests of Mac came up negative. The neurologist nonetheless recommended a second MRI, followed by another consultation with him and an inner-ear specialist. Just to be sure.

Then while I was driving Mac and two friends to a movie, he started talking about his medical odyssey, and his friends said they sometimes heard weird noises in their heads too. I called back the neurologist, and he said, yes, temporary tinnitus often arises for no discernable reason in teenagers, and usually it fades away harmlessly.

Now he tells us! To Mac’s relief, since the tinnitus had never bothered him that much, we canceled the next round of appointments. The university where I teach provides my family with excellent medical insurance, so our cost was a $20 co-payment for each visit—plus of course time and anxiety. On the other hand, all those tests and consultations easily cost thousands of dollars.

Excessive medical testing helps explain why U.S. medicine costs so much and delivers so little. In 2009 the U.S. spent $7,960 per person on health care, a rate 35 percent more than the next highest-spending nation, Norway, and more than double the rate of France, Sweden and Britain, according to an analysis by Ezekiel Emanuel, a professor of health policy at the University of Pennsylvania. And yet all these countries have much healthier populations than the U.S. does.

"Almost no matter how we measure it—whether by life expectancy or by survival for specific diseases like asthma, heart disease or some cancers; by the rate of medical errors; or simply by satisfaction with health services—the United States is actually doing worse than a number of countries, like France and Germany, that spend considerably less," Emanuel asserts. Americans rank 36th in life expectancy, tied with Cubans.

Cancer screening in particular is "vastly overused in the United States, with about 40 percent of Medicare spending on common preventive screenings regarded as medically unnecessary," according to an investigation by the Center for Public Integrity. "Millions of Americans get such tests more frequently than medically recommended or at times when they cannot gain any proven medical benefit, extracting an enormous financial toll on the nation's health care system." PSA testing alone costs about $3 billion a year, according to the test's developer, Richard Ablin, an immunologist at the University of Arizona. He calls PSA screening a "profit-driven public health disaster."

Over-testing undoubtedly stems in part from greed. Most American physicians are paid for the quantity of their care, a model called “fee for service.” Doctors have an economic incentive to prescribe tests and treatments even when they may not be needed. Physicians also over-prescribe tests and treatments to protect themselves from malpractice suits. I blame consumers, too, for being too eager to submit to tests that have negligible value. In Kolata's story on MRI scans, a physician tells her that patients "often feel like they are getting better care if people are ordering fancy tests, and there are some patients who come in demanding an MRI."

So what are my prescriptions for curbing the testing epidemic? First, the fee-for-service model should be replaced with a different compensation scheme—perhaps one that gives physicians a flat salary with bonuses for improved patient outcomes. The Mayo Clinic and other hospitals that have adopted this practice deliver better care at lower cost. Second, malpractice laws should be revised so that doctors don't prescribe tests simply to avoid lawsuits. Third, we need better evaluations of the efficacy of all medical tests. Fourth, consumers should try to educate themselves about the risks and benefits of tests. They might start by reading Overdiagnosed: Making People Sick in the Pursuit of Health (Beacon Press, 2011), by physician H. Gilbert Welch and two colleagues at Dartmouth.

Oh, in case you were wondering, my son Mac no longer hears that funny buzzing sound.

Photo courtesy Wikimedia Commons.