Missing in Action: Care by Physician Assistants and Nurse Practitioners in National Health Surveys

National health and health care surveys provide essential information for health care delivery system analysis and planning. However, because many are oriented toward traditional physician care, they may not accurately reflect the growing impact of nonphysician clinicians such as physician assistants (PAs) and nurse practitioners (NPs). In this study, we assess several surveys for use in research on PAs and NPs and identify a need for new survey methodologies that can better support incorporation of PAs/NPs into research for health care delivery system analysis and planning purposes. Owing to predicted physician shortages, economists and workforce planners are pursuing strategies to increase the U.S. physician workforce (Cooper et al. 2002; COGME 2005; Association of American Medical Colleges 2006). Because PAs and NPs provide services that often overlap substantially with those of physicians (Scheffler, Waitzman, and Hillman 1996), and because the ratio of approximately one PA or NP for every five practicing physicians is rapidly increasing (Hooker and Berlin 2002; Wing et al. 2002; Bureau of Labor Statistics 2006), PAs and NPs could buffer the predicted physician shortage and reduce the number of additional physicians needed to meet the nation's needs. Workforce planners acknowledge the need to factor the growing role of PAs and NPs into health workforce planning, but are limited by scarce research. The Council on Graduate Medical Education omitted PAs and NPs from its 2005 forecasts (COGME 2005), citing an inadequate research base. In May 2006, the American Association of Medical Colleges called for a 30 percent increase in medical school enrollment (Association of American Medical Colleges 2006) and stated that future workforce research should incorporate nonphysician clinicians. Research at the health care team, or practice, level could illuminate the overall effects of PAs and NPs on health care access, quality, utilization, and costs, as well as how PAs and NPs affect the work of physicians and, ultimately, the number of physicians needed. While research incorporating the roles of PAs and NPs is needed for national workforce planning, health workforce research is often based on data sources with varying applicability to PAs/NPs. Professional association surveys are major sources of information about the number, locations, and specialties of providers. The American Academy of Physician Assistants (AAPA) publishes well-documented and well-designed projections reflecting the national population of PAs (American Academy of Physician Assistants 2005). Because NPs have several different professional associations, data regarding NPs are more fragmented and difficult to interpret (Wing et al. 2002). Administrative data sources, such as Medicare and Medicaid billing records, provide rich data for some purposes, but have limited applicability to PAs/NPs because PA and NP services are often billed under the physician's name. Billing records often do not reflect that a PA or NP was on the team that cared for a patient (Wing et al. 2002). Inpatient care is a growing arena for PAs and NPs, but their services are similarly difficult to extract from hospitalization records. Neither the Medical Expenditure Panel Survey (MEPS) Hospital Inpatient files (Agency for Healthcare Research and Quality 2004) nor the Nationwide Inpatient Sample (Healthcare Cost and Utilization Project [HCUP] 2006), both of which collect representative hospitalization data, include data on PAs and NPs. Finally, national health and health care surveys provide data that are used to assess health care needs, quantify care provided, and examine patterns and effectiveness of care. They provide the most detailed information on what providers actually do during patient encounters, so may be the best source for addressing how PA and NP activities compare with and affect physician activities. We recognize that the surveys were designed for purposes other than PA/NP research, at a time when PAs and NPs comprised a much smaller portion of the health care workforce, so their utility for PA/NP related research might vary. In this investigation, we assess several of the widely used surveys to determine their applicability for research on team care and PA/NP care.