New research from the University of Michigan School of Nursing reveals that physicians, physician assistants and chiropractors tend to practice in more affluent areas, while nurse practitioners practice in lower income areas. Areas with the highest income and higher life expectancy had 30% more physicians and 15% fewer nurse practitioners. The American Association of Nurse Practitioners indicated that the study findings are in line with the trends they've seen in the 22 states that allow patients direct access to nurse practitioners for care.