By Perri A. Morgan and Roderick S. Hooker

DataWatch

Choice Of SpecialtiesAmong Physician AssistantsIn The United States

ABSTRACT Although the physician assistant (PA) profession was created tobolster the primary care workforce, PAs have assumed increasing roles insubspecialties. This paper compares specialty prevalence betweenphysicians and physician assistants, analyzes trends in PAs’ specialtychoices from 1997 to 2006, and suggests options for influencing thesespecialty choices in the future. The number of PAs is growing morerapidly in surgical and medical subspecialties than in primary care.Salaries loosely correlate with specialty choice, especially amongspecialties with the highest income. If there is a societal interest inencouraging PAs to practice in primary care, new economic oreducational policies may be required.

The adequacy of the medical work-force is measured by the numberand distribution of health careproviders. For a population’s needsto be met, there must be enough

providers distributed appropriately among pro-fessions, medical specialties, and geographic re-gions.1 A model health system would have theright number of providers with the right skillset in the right place at the right time. However,the United States lacks an organized system toachieve these goals.2

U.S. health workforce analysts predict a short-ageof doctors over thenext decade as a result of agrowing and aging population, increased careneeds for chronic disease, advancing technol-ogy, and economic growth.3–5 Although physi-cian shortages are expected, other providertypes are increasing innumber and are assuminga larger share of medical care.6

The U.S. health labor force includes approxi-mately 820,000 clinically active physicians, twomillion registered nurses, and approximately120,000 physician assistants (PAs) and nursepractitioners (NPs).4,7,8 With approximately68,000 PAs practicing in the United States in2007 (Exhibit 1), these providers may now be

reaching a critical mass to affect health policyand care delivery.9 There is now about one clin-ically active PA for every ten to twelve physicians.This ratio will likely tilt further toward PAs, whoare entering theU.S. healthworkforce at a rate ofabout one PA for every five physicians complet-ing postgraduate training each year.9,10 The pro-ductivity of PAs (in terms of patient visits perweek) is onparwith that of physicians.11 Analystspredict that PAs will continue to provide a grow-ing amount of patient care for the next decade.4

The role of PAs in offsetting future physicianshortages is affected by their distribution amongthe medical specialties. Although PAs were de-veloped to ease shortfalls in the primary careworkforce, many PAs practice in medical andsurgical specialties as well.9 Because they aretrained and certified as generalists, PAs canchange practice specialties throughout their ca-reers. The majority of PAs are relative newcom-ers to the profession. Half of all PAs completedtheir training within the past decade, and two-thirds did so within the past fifteen years. Be-cause PAs may be the most mobile early in theircareer trajectories, there is potential for largeand timely shifts in practice specialties amongthe PA workforce.12

doi: 10.1377/hlthaff.2008.0835HEALTH AFFAIRS 29,NO. 5 (2010): 887–892©2010 Project HOPE—The People-to-People HealthFoundation, Inc.

Perri A. Morgan(perri.morgan@duke.edu) is aclinical assistant professor inthe Department of Family andCommunity Medicine at theDuke University MedicalCenter in Durham, NorthCarolina.

Roderick S. Hooker is anadjunct professor in theSchool of Public Health,University of North TexasHealth Sciences Center andthe Department of VeteransAffairs in Dallas, Texas.

MAY 2010 29:5 HEALTH AFFAIRS 887

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With effective incentives, PAs could be de-ployed to help offset shortages in specialties orto bolster specialties experiencing the largestgrowth in demand for services. Examiningpatterns of PA specialty distribution may helpidentify influences and barriers affecting PAs’specialty choices. If they are needed in certainspecialties to help meet the health needs of thenation, policy approaches could be developed toaddress these influences and barriers so thatsocietal goals can be met.13

We set out to examine clinically active PAs byspecialty. The research question centers onwhether PA specialty distribution mirrors thatof physicians. Our aim is to examine the relativeuse of PAs by specialty, compare specialty preva-lence between physicians and PAs, analyzetrends in specialty choice among PAs, and sug-gest options for affecting choice of specialty forPAs in the future. The role of nurse practitionersand other advanced-practice nurses is importantbut beyond the scope of this study.

Study Data And MethodsData SourcesWeanalyzed data from the Ameri-can Academy of Physician Assistants (AAPA) for1992–2008, the American Medical Associationfor 1991–2005, and the Association of AmericanMedical Colleges.14–16 Descriptive statistics out-line specialty distribution for physicians andPAs. Ratios of physicians to PAs in each specialtyare presented and trends identified.Specialty categories were similar for most of

the PA and physician data. Because the AAPAdata report a “cardiovascular surgery” categorythat was not present in the physician data, thenumber of physicians in thoracic surgery andvascular surgery were aggregated to form the“cardiovascular surgery” group for physicians.

MethodsNumbers of PAs in each specialty areextrapolated from AAPA census data (2006),which targets all living PAs who ever graduatedand has a response rate of 30–35 percent. Be-cause survey weights were not available, we cal-culated the number of PAs in each specialty bysimply multiplying the proportion of survey re-spondents who indicated each specialty by thenumber of PAs estimated by the AAPA to be inclinical practice during the year.Limitations This study relied on surveys that

did not have complete response rates. Our esti-mates of numbers of PAs in each specialty weresimple unweighted extrapolations from the sur-vey. Thismethodmay have introduced some biasinto our estimates because the proclivity to re-spond to the survey could vary by specialty or byfactors related to specialty, such as year of gradu-ation. For example, because recent graduates aremore likely than others to respond to the census,this could exaggerate the observed trend towardspecialization.

Study ResultsGeneral Trends In 2007, approximately 37 per-cent of PAs worked in the primary care special-ties (family/general practice, general internalmedicine, general pediatrics, and obstetrics/gynecology). The largest segment of PAs (25 per-cent) was employed in family/general practice(Exhibit 2). This was followed by the surgicalsubspecialties, internal medicine subspecialties,and emergency medicine.Although the number of PAs rose in every spe-

cialty examined during the decade 1997–2006(in part as a result of the doubling of the PAworkforce during this period), the growth rateamong specialties was uneven (Exhibit 3).Although the total PA workforce grew 100 per-cent over this decade, the family/general prac-ticePAworkforcegrewmore slowly (39percent).Other primary care specialties also grew lessthan the overall PA workforce, with general in-ternal medicine increasing 61 percent, generalpediatrics 87percent, andobstetrics/gynecology72 percent.In contrast, subspecialty numbers increased

more than those of the total PA workforce. Thelargest growth was in internal medicine subspe-cialties, which expanded 262 percent, followedby the surgical subspecialties, which expanded186 percent.Proportions of PAs and physicians practicing

in primary care became more similar between1991 and 2005 (Exhibit 4). During the mid-1990s, the proportion of PAs in primary careincreased to around 50 percent, but by 2005 thisportion had decreased to 41 percent, compared

EXHIBIT 1

Number Of Physician Assistants In Clinical Practice, By Year, 1991–2007

Num

ber (

thou

sand

s)

SOURCE American Academy of Physician Assistants, 2009.

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888 HEALTH AFFAIRS MAY 2010 29:5

to 37 percent for physicians.Comparison By Specialty Because medical

specialties vary in numbers of physicians, weexamined ratios of PAs to physicians by spe-cialty. A useful benchmark to keep inmindwheninterpreting these results is that in 2006 therewas one PA for every twelve physicians in theworkforce; specialties with fewer than twelvephysicians per PA had a higher relative preva-lence of PAs, while those with more than twelvephysicians per PA had relatively fewer PAs.The specialties with the lowest ratios (largest

number of PAs relative to physicians) are threesurgical subspecialties—cardiovascular surgery,orthopedic surgery, and neurosurgery—whichhave approximately one PA for every three sur-geons (Exhibit 5). Dermatology and emergencymedicine are the two nonsurgical subspecialtieswith the most PAs relative to physicians, withratios of 1:5. Family/general practice, a specialtywitha traditionofhighuseofPAs,hasonePApersix physicians. The remaining primary care spe-cialtiesusePAsatmuch lower rates thanaverage.General pediatrics, for example, employs onlyone PA for every thirty-three physicians.

Physician Assistant Salaries Exhibit 5 alsopresents PA salaries for the twenty-three mostcommon specialties for which data were avail-able. The exhibit shows a correlation, especiallyin the highest salary range, between salary and

specialty prevalence for PAs. Starting salaries fornew graduatesmay be particularly important forspecialty choice. Specialty prevalence plottedagainst salaries of PAs who graduated in 2005shows a similar pattern (Exhibit 5).

EXHIBIT 2

Specialty Distribution Of Physician Assistants, 2007

SOURCE American Academy of Physician Assistants census report, 2007.

EXHIBIT 3

Change In The Numbers Of Physician Assistants, By Specialty, 1997–2006

SOURCE American Academy of Physician Assistants.

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DiscussionThe portion of PAs working in a primary carespecialty declined over a ten-year period, from54 percent in 1996 to 41 percent in 2005. Thecorresponding change among physicians wasfrom 35 percent to 37 percent (Exhibit 4).Among the primary care specialties, PAs weremore likely than physicians to practice in fam-ily/general medicine (28 percent of all PAs ver-sus 10 percent of all physicians in 2005) and lesslikely thanphysicians towork ingeneral internalmedicine, general pediatrics, or obstetrics/gyne-cology. Family/general medicine is the mostcommon specialty choice among PAs. However,the fastest-growing specialty areas for PAs arethe medical and surgical subspecialties.Specialty Variation The 2006 ratio of physi-

cians to PAs varies widely among specialties,from 6:1 in family/general medicine to 20:1 ingeneral internal medicine and 33:1 in generalpediatrics. Among the surgical specialties, PAsare most visible in cardiothoracic, orthopedic,and neurologic surgery, where the physician-to-PA ratio is 3:1. These patterns have become

EXHIBIT 4

Percentages Of Physician Assistants (PAs) And Physicians (MDs) In Primary Care Practice,1991–2005

Perc

ent

PAsMDs

SOURCES PAs: American Academy of Physician Assistants. The denominator is the number of PAseligible to practice. MDs: National Center for Health Statistics. Health, United States, 2007, withchartbook on trends in the health of Americans. The denominator is the number of active, nonfederalpatient care physicians. Osteopathic physicians are not included. Clinical fellows are included.

EXHIBIT 5

Ratios Of Physicians To Physician Assistants (PAs), And PAs’ Income By Specialty, 2005

Physician-to-PAratio

Mean PA salaryin 2005 ($)

Mean salary of PAsgraduating in 2005 ($)

Cardiovascular/thoracic surgery 3 104,681 78,052

Orthopedic surgery 3 90,093 73,112

Neurosurgery 3 93,979 76,334

Emergency medicine 5 92,896 78,308

Dermatology 5 100,735 76,244

Family/general medicine 6 78,893 66,899

Geriatrics 7 86,712 –

a

Allergy 8 78,241 65,316

Cardiology 9 88,086 71,344

Hematology/oncology 11 78,972 69,233

Urologic surgery 13 84,204 75,771

Plastic surgery 13 88,900 75,269

Endocrinology 15 75,157 68,598

General surgery 15 83,296 69,886

Otolaryngology 16 81,233 67,426

Infectious disease 18 –

a–

a

Nephrology 18 76,295 68,330

Rheumatology 19 76,336 –

a

General internal medicine 20 78,780 68,175

Pulmonary/critical care 20 89,113 –

a

Obstetrics/gynecology 26 74,658 63,968

Gastrointestinal 30 76,858 –

a

Neurology 30 76,361 69,821

General pediatrics 33 77,452 68,104

SOURCES American Academy of Physician Assistants and Association of American Medical Colleges. aData unavailable.

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890 HEALTH AFFAIRS MAY 2010 29:5

more pronounced over the past decade, with anincrease in the relative prevalence of PAs in all ofthe surgical specialties.PAs are not evenly distributed in these special-

ties, however. Financial incentives likely influ-ence specialty choice, and the five subspecialtieswith the highest mean salaries for PAs in 2005also have the highest concentration of PAs (onePA for every three to six physicians). But beyondthese five specialties, salary has little correlationwith specialty prevalence. This suggests thatother factors may lead to high (or low) use ofPAs in some specialties.

Influences On Specialty Choice There is lit-tle published information about factors that in-fluence PAs’ specialty choices. Some factors maybe similar to those that affect physicians’ choiceof specialties.17,18 These include financial factorssuch as salary, student debt load, and opportu-nities for debt forgiveness; personal factors suchas desire for a controllable lifestyle; and educa-tional institution factors such as primary caretraining emphasis.19–21

PAs’ choice of specialties is constrained by themarket of available jobopportunities. Physiciansand provider organizations may be more or lessdisposed to hire PAs in certain specialties basedon the regulatory and reimbursement environ-ment, the nature of the work, and the specialty’sexperience with PAs. For example, the high useof PAs in dermatology may be in part a result ofthe opportunity for profitable reimbursementfor minor dermatologic procedures that PAscan perform. Physicians in specialties in whichthe income differential between physicians andPAs is very largemaybemore inclined tohirePAsto save valuable physician time than those inspecialties where this is not the case. For exam-ple, orthopedic surgeons’ income is about fourtimes that of orthopedic PAs. In family practice,physicians’ income is roughly double that of PAs.Further research is needed to understand the

determinants of supply and demand for PAs byspecialty. This research would examine factorsaffecting PAs’ specialty preference (such as fi-nancial incentives, personal background, life-style aspects, personal technical versus psycho-

social orientation, and perceived social value),factors that reflect these preferences (such asnumber of PA applicants per position postedand time required to fill job vacancies), thenature of the work in each specialty (such aswhether specialty-specific tasks lend themselvesto efficient and safe task delegation), and thewillingness of physicians and organizations tohire PAs in each specialty.Policy Remedies Policy approaches that ad-

dress some of these factors could promote pri-mary care roles for PAs. Financial approachessuch as educational loan repayment programsthrough the National Health Service Corps andfavorable reimbursement structures have beeneffective for influencing job placement forPAs.22,23 Several provisions of the 2010 healthreform bill, including bonus payments for pri-mary care services, expanded loan repaymentopportunities for primary care PAs who practicein underserved areas, and increased funding forcommunity health centers, may promote pri-mary care practice for PAs. This legislation alsorestores funding for Title VII (Public Health Ser-vice Act) and carves out 15 percent of the Section747 primary care funds for PA training. In thepast, Title VII grants have been successful inpromoting primary care emphasis in PA trainingprograms.24

New policy approaches could include PA pro-gram admissions policies that favor applicantslikely to choose primary care practice, tuitionenticements for retiring military corpsmen andmedicswhocommit toworking indisadvantagedareas, and the establishment of joint familymedicine–PA program residencies to enhanceteam experience in population health.

ConclusionAs larger numbers of PAs gravitate toward spe-cialty practice, it is timely to consider the bestways for PAs to contribute to access, quality, andefficiency in the health care system. If there is asocietal interest in promoting primary care rolesfor PAs, policy safeguards and investments maybe required. ▪

An earlier version of this paper waspresented at the Association ofAmerican Medical Colleges Fourth

Annual Physician Workforce Conferencein May 2008, in Washington, D.C., and atthe Physician Assistant Educators

Association Education Forum in October2008, in Savannah, Georgia.

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NOTES

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14 American Academy of PhysicianAssistants. AAPA data and statistics[Internet]. Alexandria (VA): AAPA;2008 [cited 2010 Mar 24]. Availablefrom: http://www.aapa.org/about-pas/data-and-statistics/aapa-census

15 Association of American MedicalColleges. Physician specialty data: achart book [Internet]. Washington(DC): AAMC; 2006 Aug [cited 2008Apr 1]. Available from: https://services.aamc.org/Publications/showfile.cfm?file=version67.pdf&prd_id=160&prv_id=190&pdf_id=67

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