TUESDAY, March 10 (HealthDay News) -- Specialists are increasingly providing routine and preventive services that have traditionally been handled by primary care doctors, a new study has found.

"In a nationally representative sample of more than 25,000 visits [in the United States], we have observed that about half of all visits for specialized care is for routine and preventive care, as reported by physicians themselves," said study author, Dr. Jose M. Valderas, a clinical lecturer at the University of Manchester in the United Kingdom.

The researchers looked at data on numerous specialties, including medical, surgical, obstetrics/gynecology and psychiatry. The only specialists specifically excluded from the study were anesthesiologists, pathologists and radiologists.

After reviewing two years of data on office visits from the National Ambulatory Medical Care Survey, the researchers found that 46 percent of visits to specialists were made by people who had already been seen by the specialist and were returning for routine follow-up or preventive care. Just under a third of the visits resulted from a referral, and three-fourths of all visits to specialists resulted in a return appointment with the same physician.

The findings were published in the March/April issue of the Annals of Family Medicine.

"The problem is that specialists don't necessarily know the standard of care" for primary care, explained Dr. Sam Awada, chief of family medicine at St. John Macomb-Oakland Hospital in Warren, Mich. "For example, I knew an oncologist who was taking care of a patient, and this lady got a foot problem. He gave her Motrin, but when it persisted, and she came to see me, I discovered she had a fracture, not a sprain. That's putting yourself in a quagmire unnecessarily. If I tried to manage someone's cardiac problem or their cancer, I'd be just as guilty. It should be an easy two-way street between family doctors and specialists."

Dr. Marc Siegel, an internist at New York University Langone Medical Center in New York City, said that he "would argue that if a specialist sees you for primary prevention, you're more likely to end up having a procedure."

"Although the nation is going in the direction of specialization, it's clearly not cost-effective," Siegel said.

Valderas said that "all care that does not need the specific involvement of a specialist could potentially and should be done by primary care physicians." Looking at health-care systems worldwide, he said, "health systems oriented towards primary care have consistently demonstrated better or comparable outcomes at lower costs."