Background and Rationale
The physician assistant (PA) profession has grown dramatically in recent years, with the number of practicing PAs tripling from about 20,000 in 1991 to over 68,000 in 2008 (American Academy of Physician Assistants 2007). There is currently about one PA for every 10 physicians in clinical practice, and soon this ratio is likely to tilt further toward PAs because there is one PA entering the U.S. workforce for every six physicians (National Center for Health Statistics 2005).
PAs are providing a growing portion of office visits for medical care in the United States (Druss et al. 2003), and could buffer predicted physician shortages. How this change in the provider mix might impact overall use of medical services, however, is unknown. Does PA participation increase the effective supply of what have traditionally been physician services, or does it lead to provision of expanded or redundant services, thereby increasing per capita office visits per year?
Existing research suggests that, in the United States, participation in care by PAs and nurse practitioners (NPs) does not increase overall use of medical services, but this research is from limited settings and patient populations. Hooker evaluated the effect of provider type (PA or physician) on an episode of care for four acute uncomplicated problems in a managed area setting and found that PAs did not require more expenditures or more return visits to manage the episode of care (Hooker 2002).
In a rare randomized trial comparing provider types, Mundinger et al. (2000) found similar outcomes and health resource use among a predominantly female and Hispanic population randomized to receive primary care from either a NP or a physician for one year. The extent to which findings from these studies generalize to other settings or to care for chronic or serious conditions is unknown. Our literature review found no national study investigating the effect of PA or NP use on longitudinal health resource use.
Our results indicate that, after adjustment for a variety of indicators of patient complexity, use of PAs as the sole provider for a substantive portion of officebased visits was not associated with increased per person office visit resource use. Our study found that a group of adults with 30 percent or more of yearly visits attended by PAs alone had, on average, about 16 percent fewer visits per year. This difference could be from residual selection bias due to factors not accounted for in MEPS. Still, this study suggests that the addition of PAs to the provider mix will not increase per person office visit resource use.
In this respect, our findings indicate that PAs serve more to extend physician services to patients than to play a complementary role that leads to increased health care resource use. If predicted physician shortages (Association of AmericanMedical Colleges 2006)materialize, and if the rapid growth of the PA profession continues (Hooker 2002), PAs will provide a larger share of patient care in the United States in the future.Because labor costs for PAs are lower than those of physicians, results of this study suggest that the use of PAs may increase efficiency in health care delivery. Download entire article (PDF)
HSR: Health Services Research 43:5, Part II (October 2008)