The Contribution of Nurse Practitioners and Physician Assistants to Generalist Care in Washington State

Over the past thirty years, nurse practitioners (NPs) and physician assistants (PAs) have become an established presence in the primary health care workforce. Despite the growth of these professions, most estimates of provider shortage have focused on physicians. In this study, we describe the contribution to generalist care made by NPs and PAs in Washington State, with special attention paid to the role of nonphysician clinicians (NPCs) in underserved rural areas. Specifically, this study of Washington State addresses the following questions: What is the total contribution to generalist care made by NPCs? What is the role of NPCs in providing generalist care in rural Health Professional Shortage Areas (HPSAs)? What proportion of the total generalist care provided by women is provided by women NPCs? An important issue in health workforce analysis is how to count the contribution to patient care of each provider and each provider type. Simple head counts of providers are unlikely to produce realistic estimates of the actual supply of health care available to a population (Larson, Ballweg, and Hart 2001; Ricketts, Hart, and Pirani 2000). Differences in training, location, specialty, in-patient care activities, experience, scope of practice, and full-time/part-time status create large differences in the number of visits that a given clinician is likely to perform during a week. Data from the American Medical Association (Randolph, Seidman, and Pasko 1997), for example, indicate that an average family physician provides 105 ambulatory patient visits each week, a general pediatrician 95, and a general internist about 65. If estimates of available care are to include NPCs, basing estimates of available care on head counts becomes yet more doubtful because so little is known about the productivity of NPCs and their total contribution to care (Scheffler, Waitzman, and Hillman 1996). In this study, we use state licensing data and self-reports of outpatient visit productivity to count contribution to care by providers in family physician full-time equivalents (FTEs). By measuring productivity in this way, we can correct for individual differences in productivity and directly compare productivity across professions. Because the analysis is based on individual-level productivity data, we are able to base our analysis on FTEs rather than head counts of providers. While many states and other jurisdictions do not have the data necessary to carry out such an analysis, this work presents some empirically derived “productivity adjustment factors” for different provider types in different settings. If we can determine, for example, that full-time PAs perform 70 percent of the number of visits performed by full-time family physicians, we can, in the absence of actual visit data, use the .7 productivity adjustment to estimate the contribution to care made by a PA in meeting the visit requirements of a population. Productivity adjustments can be used to estimate available care based on provider type, specialty, and location when productivity data are not available.