More doctors follow the money, more nurse practitioners follow the need

The issue becomes more interesting when you account for health care's changing provider landscape -- specifically, the growing number of physician assistants and nurse practitioners.

"The U.S. health workforce is now an eclectic mix of different providers. We thought it'd be interesting to see if other providers such as nurse practitioners and physician assistants established their practices in more affluent communities such as medical physicians," said Matthew Davis, assistant professor at the U-M School of Nursing.

Researchers compared the number of physicians, physician assistants, nurse practitioners and chiropractors available in counties at different levels of income and health status. They used life expectancy as an indicator of the need for health care.

They found that more physicians, physician assistants and chiropractors are available in the most affluent areas with already high life expectancy, which falls in line with conventional thinking. However, more nurse practitioners practiced in lower income areas with low life expectancy, which could to some degree offset a dearth of doctors in high-need areas.

There were 30 percent more physicians but 15 percent fewer nurse practitioners in the highest income areas, when compared to the lowest income areas, Davis said. When the researchers examined where nurse practitioners work, they found that the availability of nurse practitioners was about 50 percent higher in the least healthy counties compared with the healthiest.

"That was nice to see," Davis said. "The nurse practitioner workforce appears to be having some positive effects. Our work shows that nurse practitioners are more likely to set up shop in areas of higher need and other studies have shown that they provide a substantial amount of care for individuals with chronic illness."

The availability of physician assistants mirrored that of physicians, probably because these two disciplines are often tied together through licensure.

Chiropractors were most likely to work in areas of high income and greater health. Most chiropractors are small business owners, so it makes sense that those providers would locate in higher income areas, where demand is probably greater. A study last year conducted for the Association of American Medical Colleges predicted a shortage of between 40,800 and 104,900 primary and specialty care physicians by 2030. One thought is that the growing number of physician assistants and nurse practitioners can help meet the growing demand for primary care. The Bureau of Labor statistics projects that the number of physician assistants and nurse practitioners will grow 37 percent and 31 percent respectively, which is much faster than the 7 percent average growth for other occupations.

This is due to the aging population, demand for preventive care and overall increased demand for health care services. Employment of physicians and surgeons is expected to grow only 13 percent during the same time period.

The study, "Supply of healthcare providers in relation to county socioeconomic and health status," appears in the Journal of General Internal Medicine.

Davis also has an appointment at U-M's Institute for Social Research and is a faculty affiliate of the U-M Institute for Healthcare Policy and Innovation.