Although the image of the lone physician motoring down back roads for house calls or tending to a waiting room full of patients in a quaint office might be charming, the reality is that most doctors aren't loners.
Various surveys and studies suggest that only about a third of physicians practice alone or with a single partner, largely because docs have had to join forces in larger groups to handle paperwork and insurance claims. Most medicos work for hospitals or group practices with more than six doctors.
Even those who practice "alone" are bound to their peers by medical associations, hospital affiliations -- and the patients they share.
A new analysis of those patient-centered ties suggests that docs continue to interact with each other differently in different parts of the country, despite forces that try to impose uniformity on the practice of medicine.
Researchers from Harvard Medical School and Beth Israel Deaconess Medical Center in Boston looked at Medicare data for more than 4.5 million patients seen by nearly 70,000 doctors in 51 "hospital referral regions" in urban and rural areas around the country.
They used the data to see how networks were formed based on which doctors shared patients.
The study's lead author, Dr. Bruce Landon, a professor of health-care policy at Harvard and a primary care specialist at the medical center, said by taking advantage of the insurance data from across the country, the researchers are able to develop insights into how physicians work together to care for patients that otherwise would only be possible by taking surveys within individual hospitals or practice groups.
Their report, published in the July 18 issue of The Journal of the American Medical Association, found that physicians tend to share patients with doctors that share similar backgrounds such as age, gender (especially for male doctors) and that are based at the same hospital. They're also more likely to share patients if their practices have patients with similar problems, or have similar racial backgrounds.
Understanding how informal physician networks are organized helps researchers learn how new ideas and practices spread, and why health-care practices often vary widely across geographic areas.
For instance, the study found that doctors in Albuquerque, N.M., were mainly connected to physicians within their own hospitals and less likely to share patients with doctors affiliated with other hospitals; physicians in Minneapolis were much less influenced by hospital connections among the patients they shared with other docs.
Of course, the number of physicians in a market affects the number of ties. The 135 Medicare physicians in Minot, N.D., had patient connections with just 11.7 other physicians per 100 Medicare patients. The 8,197 doctors in Boston had ties to 51.4 other physicians per 100 patients.
"We know that doctors learn through other doctors," said Dr. Nicholas Christakis, senior author and a professor of medicine and medical sociology at Harvard. "So, by examining these patient-sharing networks, we can see how innovations -- new technology, new drugs, new practices such as test ordering -- begin to diffuse throughout a network."
On the other hand, the researchers said if physicians mainly flock together with other doctors who practice medicine they same way they already do, it could stifle innovation.
Equally important for patients is how the informal networks affect the quality of care and the sharing of information.
Health insurers, employers and the federal government are spending billions to encourage the formation of "accountable care organizations," where groups of doctors, hospitals and other providers get incentives to collaborate, share information and coordinate patient services.
Medicare, for example, in June announced a new program in all or part of eight states that will pay select primary-care groups an extra $20 a month per beneficiary to offer more flexible hours, electronic records, more preventive care and enhanced coordination of care among providers.
Landon and Christakis note that in some places, it might make more sense to organize care management around the existing informal physician networks rather than to set up new structures.
(Contact Scripps health and science reporter Lee Bowman at BowmanL@shns.com .)
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