Dr. Elliott Fisher, the director of the Center for Health Policy Research at TDI, Dartmouth's health-policy institute, has worked with Goodman on numerous studies of the physician workforce. He believes if health-care delivery were more efficient, "we probably could get rid of 20 or 30 percent of American physicians, with better outcomes and lower costs." The problems the AAMC cites as evidence of a shortage, he says, "are actually mostly a consequence of a disorganized delivery system."

Fisher's argument is backed up by many TDI studies, including the Dartmouth Atlas of Health Care, a series of reports on geographic patterns in health-care usage. The 2008 Dartmouth Atlas examined end-of-life treatment and Medicare spending and found that large variations in spending could only be accounted for by supply-sensitive care. In other words, regions with more health-care resources—such as physicians and hospital beds—provided more care without necessarily improving patients' health. In fact, the study showed that, paradoxically, higher spending led to lower quality of life and slightly worse outcomes.

Goodman and Fisher are far from alone in making these arguments. "Many Americans are getting too much health care. . . . Obviously the Wennberg group has shown this for years," says Jonathan Weiner, the Johns Hopkins researcher. Dr. Russell Robertson, a professor and chair of family medicine at Northwestern's Feinberg School of Medicine and the current chair of COGME, also speaks enthusiastically about the TDI research. "It's clear that physicians play a significant role in the increased costs with regard to health care," he says.

But not everyone is convinced, and perhaps no one less so than Dr. Richard Cooper, a professor of medicine at the Hospital of the University of Pennsylvania and former dean of the Medical College of Wisconsin. His has been one of the loudest voices calling for more physicians, and his work has often been cited by the AAMC as evidence for the need to increase medical school enrollments.

Cooper has pointed out that since 1929, there has been a correlation between economic growth and an increase in physician supply. Based on that historical model, he predicts that the physician shortage could reach 200,000 by 2020. So his conclusions are similar to those of the AAMC, but his approach is quite different. "What matters is how much money is available for the health-care system," he says. "Demographics don't matter." If the economy continues to grow, he contends, there will inevitably be

a significant shortage of physicians. Of course, he notes, long-term economic decline would change that projection.

Cooper also rejects the argument that physicians can drive the use of health-care services. "Physicians don't cause colon cancer," he says. "They don't cause breast cancer. They don't cause heart attacks." What does drive health-care spending, he argues, is patient demand.

But denying the existence of supply-sensitive care is "a little bit like saying the sun doesn't rise in the east," says Shannon Brownlee, a senior fellow at the New America Foundation and the author of Overtreated: Why Too Much Medicine Is Making Us Sicker and Poorer. "How can you not believe this after the amount of information, the quality of information,

that Dartmouth has compiled?" she asks. The problem with the argument that patient demand determines the use of health-care, she says, is that it assumes that the market actually works. "The assumption says [that] where there are more sick people, there will be more hospital beds and more doctors—but that's not what we're seeing," she says. Instead, research has shown that an overabundance of beds and doctors contributes to overutilization of those resources.

DMS's Nierenberg describes himself as a "middle-of-the-roader" in the workforce debate. "I believe there's a lot of waste in the system," he says. But, he feels, getting rid of that waste probably won't be enough by itself to meet the need for physicians. "I worry about large pockets of rural communities or inner-city communities that have virtually no medical services," he says.

The AAMC's Salsberg raises that concern as well. He says that if there is a physician shortage, those Americans who already lack adequate health care will be hardest hit. Goodman's arguments "sort of assume that the system is going to just miraculously turn around and reduce the marginally beneficial services," he says. "We worry that if you just assume the system is going to change, that the nation's going to find itself very seriously short, and that there will be major delays