Increasing access to primary care is a key focus of health reform in the United States. Primary care helps patients in decision making, provides opportunities for disease prevention and health promotion, and can engage patients’ family and community to help meet the health needs of the patients. States with a higher ratio of primary care physicians to patients have lower Medicare expenditures and lower total and disease-specific mortality. However, since 1998 the proportion of US medical students choosing careers in primary care has dropped from around 60 percent to 20–27 percent.
One way to address the shortage of physician primary care providers is with nurse practitioners (NPs). The past two decades have witnessed an increase in NP training programs and the number of practicing NPs. However, states vary greatly in regulating the scope of NPs’ practice and in the precision and detail of those regulations. In some states NPs have essentially the same authority to practice that physicians have. Other states require physician supervision and limit NPs’ hospital privileges as well as their authority to order tests, make referrals, and prescribe medications. The online Appendix contains (in Exhibits 1a and 2a)15 a summary of regulations for each state and how they have changed over time. These restrictions may inhibit the spread of care provided by NPs.
Previous studies have found an increase over time in both the number of nurse practitioners and the number of patients receiving care from them. These studies were based on national health care surveys and included small numbers of NPs. In this article we assess the growth in care provided by nurse practitioners from 1998 through 2010 and how this varies by practice setting, using national Medicare data as well as the number of licensed NPs as reported by state authorities. We were particularly interested in the variation among states in NPs serving as primary care providers. We hypothesized that states with fewer restrictions on NP practice and areas with a lower supply of primary care physicians and physician assistants would have the highest percentage of NPs as primary care providers.”