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The evidence isn’t always stellar // Guidelines don’t account for patient differences // Experts often disagree about the facts.

Evidence-Based Medicine: Burden of Proof

By Anita Slomski // Photo Illustrations by Nigel Cox // Spring 2010
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evidence-based medicine

Nigel Cox for Proto

Last November the U.S. Preventive Services Task Force unleashed a maelstrom when it recommended against routine mammography for women younger than age 50 and advised physicians not to teach women how to do breast self-exams. The response was swift and fierce, with such celebrities as Jaclyn Smith and Sheryl Crow—both breast cancer survivors—leading the vanguard in proclaiming the new recommendations to be misguided and dangerous.

Physicians lined up right behind them. “This is a giant step backward and a terrible mistake,” oncologist Marisa Weiss told the New York Times. “We know mammography overperforms and finds things that will never be life-threatening, and we know it underperforms,” said Weiss, who is the founder of “But it has no chance to perform in women who don’t get it.” Added Christine Hodyl, director of breast surgery at South Nassau Communities Hospital in Oceanside, N.Y., “I can’t tell you how many times we pick up a cancer in a young woman who comes in for a baseline mammogram before age 40.”

But the USPSTF’s recommendations were based on the best research and decision-making that medicine has to offer. A panel of primary care physicians and scientists—not oncologists or radiologists, who might have a financial stake in breast cancer treatment or prevention—considered the results of numerous randomized trials and commissioned its own study before concluding that 1,904 women in their forties would have to be screened with mammography to prevent just one death from breast cancer. That benefit did not outweigh the risks of false-positive findings, which would subject women to unnecessary biopsies, anxiety and treatment of benign breast conditions, according to the USPSTF, which urged women to discuss the benefits and tradeoffs with their doctors. The panel also found no evidence to support the utility of breast self-exams, citing data indicating that most lumps women find are benign and don’t merit the biopsies that often follow.

The new mammography recommendations joined a growing body of research that falls under the rubric of evidence-based medicine. This approach is based on the belief that medical care will be better, safer and more efficient if physicians base clinical judgments on solid empirical science. Backed by such evidence, government agencies, specialty medical societies, disease associations and large health plans have developed guidelines that set out exactly which drugs, tests and treatments doctors should use to manage a vast array of medical conditions. Insurers follow evidence-based guidelines to make decisions about which interventions they will cover. And Medicare and private health plans have utilized guidelines to extrapolate hallmarks of quality and hold physicians and hospitals accountable for meeting them.

Instead of receiving gratitude for improving care, however, the USPSTF found itself at the center of controversy. “Breast cancer is a topic of great emotional and physical meaning for women, and the guidelines were created by a group whose name suggested it was a governmental body with an interest in controlling costs,” says Steven Pearson, a physician and president of the Institute for Clinical and Economic Review. Based at Massachusetts General Hospital’s Institute for Technology Assessment and affiliated with Harvard Medical School, ICER is a policy group that weighs the effectiveness and the cost of medical treatments. In fact, says Pearson, the USPSTF is an independent organization. “The announcement explaining why the recommendations had changed was very badly managed,” he explains. “And the battles over health care reform going on at the same time just turned up the volume.”

The furor illustrates one of the biggest problems with evidence-based medicine—that it can be almost impossible to produce the kind of rock-solid evidence that will convince physicians (and the public) that a particular intervention, preventive measure or diagnostic test really is the best medicine. Though the USPSTF recommendations were never meant to apply to every patient, nuance was quickly lost in the uproar. Those who objected to the organization’s conclusions simply found medical evidence they liked better: the American Cancer Society’s guidelines calling for women to receive yearly mammograms once they turn 40. “It can be challenging to make medical decisions when august groups of clinical experts look at the same evidence and, based on their beliefs about its strength, come to very different conclusions,” Pearson says.

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1. “Where Is the Wisdom? A Conceptual History of Evidence-Based Medicine,” by Peter C. Wyer and Suzana A. Silva, Journal of Evaluation in Clinical Practice, September 2009. Tracing evidence-based medicine’s origins in the 1970s through its “crowning achievements” during the information age, the authors argue that EBM does not threaten individualized care, as some believe, but rather informs it.

2. “Comparative Effectiveness and Health Care Spending—Implications for Reform,” by Milton C. Weinstein and Jonathan A. Skinner, The New England Journal of Medicine, Jan. 6, 2010. Comparative-effectiveness research alone won’t cut health care costs, these authors say. Physicians and hospitals must make hard decisions about where limited resources will do the most good.

3. “Imaging Idolatry: The Uneasy Intersection of Patient Satisfaction, Quality of Care, and Overuse,,” by Richard A. Deyo, Archives of Internal Medicine, May 25, 2009. Deyo explores the conundrum physicians face when evidence-based guidelines clearly indicate one approach to treating back pain but patients demand another.

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