Whose patient is it?

Of course, it's understandable that a patient with cancer would get most of his care from an oncologist, or someone with ESRD would see a nephrologist most of the time. But Kagan and other primary care physicians say this also happens with some patients who have nonlife-threatening conditions. And if a subspecialist really tries to provide all of a patient's primary care, says Kagan, the results can be disheartening.

"There was one cardiologist who was doing a patient's physicals for a couple of years, and the guy kept on getting more and more anemic. The specialist never thought to look at whether this guy could have colon cancer-which is what he had. Ask any primary care doctor, and that's the first thing they think of when a man gets progressively more anemic.

According to primary care physicians, consultants, and workforce experts interviewed for this article, many generalists have had subspecialists "poach" patients from them. Most of the primary care doctors we surveyed said they never again refer to a doctor who does that. Subspecialists are well aware of that sensitivity, so they usually urge patients to return to referring doctors. But they say that the situation is more complex than that, because patients often demand primary care services, even if those are outside their specialty field. Also, some subspecialists contend that they can take better care of chronic-disease patients if they assume some of their primary care.

Moreover, subspecialists note, there are areas of medicine that primary care physicians aren't well-qualified to handle. For example, infectious disease specialist Richard C. Prokesch, from Atlanta, has found that most primary care doctors in his area don't know how to manage the multiple medications that their HIV/AIDS patients are on. They also don't know how to diagnose their acute conditions. "These patients will go to a primary care physician with what seems like a cold," he says. "It's really an opportunistic infection, and the doctor doesn't have enough experience to act on it early enough."

Consequently, Prokesch tells his HIV/AIDS patients to call him if they have a fever or what they think is the flu. But he doesn't try to provide all primary care to any of his patients-a practice that's known as "principal care." If they need services outside his field, he'll refer them to generalists or other specialists.

Except in a few parts of the country, principal care provided by subspecialists doesn't appear to be a major economic threat to primary care doctors. Because most of them are so busy, the few patients they may lose to subspecialists don't represent much of their business. But some primary care physicians and medical leaders view principal care as a threat to the continuity of care. There's also some evidence that healthcare is better and less expensive when generalist physicians provide as much of it as they can and coordinate the rest.

Here's a bird's-eye view of why principal care exists, what it doesn't cover, and what you can do to make sure that your patients don't fall between the cracks.