Autonomous ambulatory care by nurse practitioners and physician assistants in office-based settings.

Data from the 1997 National Ambulatory Medical Care Survey were used to examine the autonomous provision of ambulatory medical care by nurse practitioners (NPs) and physician assistants (PAs) in physician-managed office-based settings. An estimated 6.81 million office visits involved autonomous care by NPs and PAs, for an overall rate of 2.55 visits per 100 persons. The visit rates were greatest for patients over 64 years of age, females, blacks, and patients from the Northeast. The visits encompassed a broad range of acute and chronic problems, with a greater proportion of non-illness care visits when compared with visits to physicians. While NPs and PAs provided diagnostic services and pharmacotherapy, there was more emphasis on therapeutic or preventive services in their practices than among physicians' practices. Predisposing, enabling, and need factors were differentially associated with visits to NPs and PAs. Utilization of NPs and PAs as autonomous providers in office-based settings appears limited. Public policy and educational initiatives can focus on predisposing, enabling, and need factors to increase access to autonomous practice of NPs and PAs in ambulatory care.