NCHS Data Brief ■ No. 151 ■ May 2014

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

State Variability in Supply of Office-based Primary Care 

Providers: United States, 2012

Esther Hing, M.P.H., and Chun-Ju Hsiao, Ph.D.

Key findings

Data from the National 

Ambulatory Medical Care 

Survey (NAMCS) and the 

NAMCS Electronic Health 

Records Survey

• In 2012, 46.1 primary care 

physicians and 65.5 specialists 

were available per 100,000 

population.

• From 2002 through 2012, 

the supply of specialists 

consistently exceeded the 

supply of primary care 

physicians.

• Compared with the national 

average, the supply of primary 

care physicians was higher in 

Massachusetts, Rhode Island, 

Vermont, and Washington; 

it was lower in Arkansas, 

Georgia, Mississippi, Nevada, 

New Mexico, and Texas.

• In 2012, 53.0% of officebased primary care physicians 

worked with physician 

assistants or nurse practitioners.

• Compared with the national 

average, the percentage of 

physicians working with 

physician assistants or nurse 

practitioners was higher in 19 

states and lower in Georgia.

Primary care providers include primary care physicians, physician assistants, 

and nurse practitioners. Primary care physicians are those in family and 

general practice, internal medicine, geriatrics, and pediatrics (1). Physician 

assistants are state-licensed health professionals practicing medicine under 

a physician’s supervision. Nurse practitioners are registered nurses (RNs) 

with advanced clinical training (2–6). The ability to obtain primary care 

depends on the availability of primary care providers (3). This report presents 

state estimates of the supply of primary care physicians per capita, as well 

as the availability of physician assistants or nurse practitioners in primary 

care physicians’ practices. Estimates are based on data from the National 

Ambulatory Medical Care Survey (NAMCS), Electronic Health Records 

(EHR) Survey, a nationally representative survey of office-based physicians.

Keywords: primary care physicians • physician assistants • nurse practitioners

During the last decade, the supply of primary care physicians 

was lower than the supply of specialty physicians. Number per 100,000 population

NOTES: Rate of specialty physicians per 100,000 population exceeds primary care physician rate for every year shown (p < 0.05). 

Primary care physicians include those in family and general practice, internal medicine, geriatrics, and pediatrics. 

SOURCES: CDC/NCHS, National Ambulatory Medical Care Survey (NAMCS) and NAMCS, Electronic Health Records Survey.

Figure 1. Number of primary care and specialty physicians per 100,000 population: United States, 

2002–2012

0

45

50

55

60

65

70

Specialty physicians

Primary care physicians

2007 2008 2009 2010 2011 2012

Year

2002 2003 2004 2005 2006
NCHS Data Brief ■ No. 151 ■ May 2014

■  2  ■

• The overall supply of primary care physicians did not change significantly between 2002 

and 2012 (46.7 and 46.1 per 100,000 population, respectively) (Figure 1).

• From 2002 to 2012, the supply of specialists consistently exceeded the supply of primary 

care physicians. The ratio of primary care physicians to specialists in 2012 was 0.70 and had 

remained stable from 2002 to 2012.

The supply of primary care physicians varied by state in 2012.

• The supply of primary care physicians per 100,000 population varied by state, ranging from 

26.5 in Mississippi to 93.7 in Hawaii (Figure 2).

• The supply of primary care physicians exceeded the national average in four states 

(Massachusetts, Rhode Island, Vermont, and Washington) and was lower than the national 

average in six states (Arkansas, Georgia, Mississippi, Nevada, New Mexico, and Texas).

Figure 2. Number of primary care physicians per 100,000 population: United States, 2012 

NOTES: Primary care physicians include those in family and general practice, internal medicine, geriatrics, and pediatrics. Significance was tested at the p < 0.05

level. 

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, Electronic Health Records Survey.

CA

AK

HI

Significantly lower than national average

Not significantly different from national average

Significantly higher than national average

ID

WA

OR

NV

AZ

ND

SD

NE

TX

KS MO

IA

MN

IL IN

MS

FL

OH

MI

PA

MD

DE

NJ

CT

RI

MA

VT ME

NH

MT

WY

UT

CO

NM

WI

DC

NY

SC

NC

GA

VA

AL

KY

WV

TN

OK

AR

LA

National average: 46.1

59.6

41.2

39.4

47.3

93.7

33.9

54.5

51.4

38.4

42.5

41.6

45.7

36.2

41.2

41.1

41.2

33.6

38.3

42.7

43.6

36.4

47.5 35.5

44.6

43.5

39.0

56.8

26.5

37.0

47.0

52.7

52.3

56.2

50.4

49.7

66.8

44.5

38.7

36.3

31.0

44.3

50.3 70.2

58.1

53.7

66.6

65.7

54.1

43.9

53.8

59.1

The percentage of primary care physicians with physician assistants or 

nurse practitioners in their practices varied by state.

• Overall, 53.0% of primary care physicians worked with physician assistants or nurse 

practitioners in their practices in 2012.

• The percentage of primary care physicians working with physician assistants or nurse 

practitioners varied by state, ranging from 33.4% in the District of Columbia to 89.6% in 

South Dakota (Figure 3).
NCHS Data Brief ■ No. 151 ■ May 2014

■  3  ■

• In 19 states (Alaska, Arizona, Idaho, Iowa, Kansas, Maine, Massachusetts, Minnesota, 

Montana, Nebraska, New Hampshire, New Mexico, North Carolina, North Dakota, South 

Dakota, Tennessee, Vermont, Wisconsin, and Wyoming), the percentage of physicians 

having physician assistants or nurse practitioners in their practices exceeded the national 

average; in Georgia, this percentage was lower than the national average.

• The percentage of primary care physicians with physician assistants or nurse practitioners in 

their practices in 2012 (53.0%) was similar to that in 2006 (51.2%), the first year in which 

NAMCS collected this information (data not shown).

Figure 3. Percentage of office-based primary care physicians with physician assistants or nurse practitioners in their 

practices: United States, 2012

NOTES: Primary care physicians include those in family and general practice, internal medicine, geriatrics, and pediatrics. Data omit 2.8% of physicians for whom

information on physician assistants or nurse practitioners was missing. Significance was tested at the p < 0.05 level.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, Electronic Health Records Survey.

CA

AK

HI

Significantly lower than national average

Not significantly different from national average

Significantly higher than national average

ID

WA

OR

NV

AZ

ND

SD

NE

TX

KS MO

IA

MN

IL IN

MS

FL

OH

MI

PA

MD

DE

NJ

CT

RI

MA

VT ME

NH

MT

WY

UT

CO

NM

WI

DC

NY

SC

NC

GA

VA

AL

KY

WV

TN

OK

AR

LA

National average: 53.0

82.8

38.7

45.4

58.3

61.7

72.7 74.8

66.2

65.1

75.5

77.3

89.1

60.9

74.2

73.8

80.7

61.5

89.6

47.0

49.7

74.3

71.5

50.2

84.9

61.1

55.6

72.5

42.2 56.9

47.8

54.3

48.5

44.5

62.9 54.5

78.6

46.1 34.8

43.9

49.6

41.6

64.9

33.4

47.3

49.8

81.6

44.2

72.1

74.9

77.1

40.6

The availability of primary care physicians and the percentage of primary 

care physicians working with physician assistants or nurse practitioners 

varied by the urbanicity of the physician’s office location.

• The supply of primary care physicians was significantly greater with increasingly urban 

physician’s office locations, from 39.8 per 100,000 population in nonmetropolitan areas to 

53.3 in large central metropolitan areas (Figure 4).

• The percentage of primary care physicians with physician assistants or nurse practitioners 

in their practices decreased with increasingly urban office locations, from 65.5% in 

nonmetropolitan areas to 41.9% in large central metropolitan areas.
NCHS Data Brief ■ No. 151 ■ May 2014

■  4  ■

Figure 4. Availability of primary care physicians and percentage of primary care physicians working with physician 

assistants or nurse practitioners, by urbanicity of physician’s office location: United States, 2012 

1

Significant increasing linear trend by urbanicity (p < 0.05).

2

Significant association between percentage with physician assistant or nurse practitioner and urbanicity (p < 0.05).

NOTES: Primary care physicians include those in family and general practice, internal medicine, geriatrics, and pediatrics. Data omit 2.8% of physicians for whom 

information on physician assistants or nurse practitioners was missing.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, Electronic Health Records Survey.

Number of primary care physicians

per 100,000 population1

Percentage with physician assistant or 

nurse practitioner in practice2

0 20 40 60

Nonmetropolitan

Medium or small

metropolitan

Large fringe

metropolitan

Large central

metropolitan 53.3

44.7

43.4

39.8

41.9

52.3

60.4

65.5

0 20 40 60 80

Primary care physicians in multispecialty group practices were more likely 

than those in solo or partner practices to work with physician assistants or 

nurse practitioners.

• A higher percentage of primary care physicians in multispecialty group practices (three 

or more physicians with different specialties) worked with physician assistants or nurse 

practitioners (77.5%) compared with those in small (solo or partner) practices (36.3%) 

(Figure 5).

• Among group practices, a higher percentage of primary care physicians in multispecialty 

practices worked with physician assistants or nurse practitioners (77.5%) compared with 

those in single-specialty practices (56.6%).

Summary

From 2002 to 2012, the supply of primary care physicians, measured as the number per 100,000 

population, was stable, as was the ratio between primary care physicians and specialists, 

continuing a trend observed since the 1990s (7–9). In 2012, the supply of primary care physicians 

varied by state. In four states (Massachusetts, Rhode Island, Vermont, and Washington), the 

supply of primary care physicians was higher than the national average of 46.1 per 100,000 

population; in six states (Arkansas, Georgia, Mississippi, Nevada, New Mexico, and Texas), the 

supply was lower than the national average.

Physician assistants and nurse practitioners provide a substantial amount of primary care (2,3). 

A previous study found twice as many nurse practitioners (18.9%) as physician assistants 
NCHS Data Brief ■ No. 151 ■ May 2014

■  5  ■

Figure 5. Percentage of primary care physicians working with physician assistants or nurse practitioners, by practice type: 

United States, 2012

1

Significantly different from solo or partner practice (p < 0.05).

2

Significantly different from multispecialty group practice (p < 0.05).

NOTES: Primary care physicians include those in family and general practice, internal medicine, geriatrics, and pediatrics. Data omit 2.8% of physicians for whom 

information on physician assistants or nurse practitioners was missing.

SOURCE: CDC/NCHS, National Ambulatory Medical Care Survey, Electronic Health Records Survey. Percent

0

20

40

60

80

100

Multispecialty group Solo or partner Single-specialty group1,2 1

36.3

56.6

77.5

(10.3%) among primary care providers (5). In 2012, 53% of primary care physicians had 

physician assistants or nurse practitioners in their practices. States varied in the availability of 

physician assistants and nurse practitioners in physician offices. The percentage of physicians 

with physician assistants or nurse practitioners in their practices exceeded the national average 

in 19 states (Alaska, Arizona, Idaho, Iowa, Kansas, Maine, Massachusetts, Minnesota, Montana, 

Nebraska, New Hampshire, New Mexico, North Carolina, North Dakota, South Dakota, 

Tennessee, Vermont, Wisconsin, and Wyoming) and was lower than the national average in 

Georgia.

Physician assistants and nurse practitioners are more prevalent in rural and underserved areas, 

which have fewer primary care physicians (2,3,10). The findings—that the supply of primary 

care physicians increased as office locations became more urban, whereas the inclusion of 

physician assistants or nurse practitioners in primary care physician practices increased as office 

locations became less urban—are consistent with previous studies (2–4,10,11). State variation in 

the availability of physician assistants or nurse practitioners in primary care physician practices 

may also depend on the presence of integrated health care delivery systems, such as group health 

maintenance organizations, which include physician assistants and nurse practitioners more often 

than other physician practices (11). Our study found that physicians in multispecialty group 

practices had physician assistants or nurse practitioners in their practices more often than did 

single-specialty group practices or small (solo or partner) practices. Other factors, such as state 

variation in scope-of-practice laws for physician assistants and nurse practitioners and insurance 

payment policies, also affect the availability of physician assistants and nurse practitioners in 

physician practices (2–4,10,11).
NCHS Data Brief ■ No. 151 ■ May 2014

■  6  ■

Definitions

Nurse practitioner: Defined as an RN with advanced training in areas not usual for RNs, such 

as diagnosing and managing common diseases, ordering tests, and prescribing medications. 

Although several types of RNs have advanced training, most advanced practice nurses working in 

the offices of primary care physicians are nurse practitioners (5,6). Nurse midwives, another type 

of advanced practice nurse, typically work with obstetricians or gynecologists (6).

Supply of primary care physicians per 100,000 population: Defined as the number of primary 

care physicians divided by the civilian noninstitutionalized population in the United States as of 

July 1, 2012. Primary care physicians include office-based physicians in the specialties of family 

and general medicine, internal medicine, geriatrics, and pediatrics. The population estimates by 

state were prepared by the Population Division, U.S. Census Bureau. Population estimates by 

urban or rural classification are based on estimates of the civilian noninstitutionalized population 

in the United States as of July 1, 2012, from the 2012 National Health Interview Survey, 

National Center for Health Statistics (NCHS), compiled according to December 2009, Office of 

Management and Budget definitions of core-based statistical areas. For more information, see the 

U.S. Census Bureau’s metropolitan and micropolitan website: http://www.census.gov/population/

metro/. 

Urban or rural classifications of the physician office’s ZIP code: Developed by the Centers for 

Disease Control and Prevention’s (CDC) NCHS to study the association between urbanicity and 

health and to monitor the health of urban and rural residents. The six-level classification scheme 

is based on county or county equivalents and Office of Management and Budget definitions.

Large central metropolitan area—An urban area; specifically, a county in a metropolitan 

statistical area (MSA) with a population of 1 million or more that contains the entire 

population of the largest principal city of the MSA, or whose entire population resides in the 

largest principal city of the MSA, or that contains at least 250,000 of the population of any 

principal city in the MSA.

Large fringe metropolitan area—A large suburban area; specifically, a county in an MSA 

with a population of 1 million or more that does not qualify as a large central metropolitan 

area.

Medium metropolitan area—A county in an MSA with a population of 250,000–999,999.

Small metropolitan area—A small town or suburb; specifically, a county in an MSA with a 

population of 50,000–249,999.

Rural or nonmetropolitan area—A county that is outside of any MSA (12). 

Data sources and methods

Data for this report are from the NAMCS and the NAMCS EHR Survey, which are conducted by 

NCHS as annual, nationally representative surveys of office-based physicians. The target universe 

of the NAMCS and NAMCS EHR Survey is physicians classified as providing direct patient 

care in office-based practices, including clinicians in community health centers. Radiologists, 

anesthesiologists, and pathologists are excluded.
NCHS Data Brief ■ No. 151 ■ May 2014

■  7  ■

The NAMCS EHR Survey was first conducted in 2008 as a mail survey supplemental to the core 

NAMCS, which is an in-person survey. The NAMCS EHR Survey collects information on the 

adoption and use of EHR systems. In 2010, the NAMCS EHR survey sample size was increased 

fivefold to allow for state-level estimates.

The 2012 estimates are from the NAMCS EHR survey, with a sample of 10,302 physicians. 

Nonrespondents to the mail survey received followup telephone calls. Updated physician 

specialties were obtained from the survey. Use of midlevel providers in the physician offices was 

obtained from the question “How many midlevel providers (i.e., nurse practitioners, physician 

assistants, and nurse midwives) are associated with this office?” The 2012 mail survey was 

conducted from February through June 2012. The unweighted response rate for the 2012 mail 

survey was 68% (66% weighted). A copy of the 2012 survey is available from the NCHS website: 

http://www.cdc.gov/nchs/data/ahcd/2012_EHR_Survey.pdf. 

Statements of differences in estimates are based on statistical tests with significance at the 

p < 0.05 level. Differences by selected physician characteristics were examined using t tests 

for differences in percentages and Chi-square tests for differences in percent distributions. A 

weighted least-squares regression analysis was used to determine the significance of per capita 

supply of primary care physicians by urbanicity of physician office location (13).

About the authors

Esther Hing is with CDC’s National Center for Health Statistics, Division of Health Care 

Statistics, Ambulatory and Hospital Care Statistics Branch; Chun-Ju Hsiao is with the Agency for 

Healthcare Research and Quality.

References

1. Centers for Medicare & Medicaid Services. Pub 100-04 Medicare claims processing. CMS 

Manual System. Transmittal 2161. Baltimore, MD: Centers for Medicare & Medicaid Services. 

2011. Available from: http://www.cms.gov/Regulations-and-Guidance/Guidance/Transmittals/

downloads/R2161CP.pdf.

2. Cunningham R. Tapping the potential of the health care workforce: Scope-of-practice and 

payment policies for advanced practice nurses and physician assistants. Background paper no 76. 

Washington, DC: National Health Policy Forum, The George Washington University. 2010.

3. Paradise J, Dark C, Bitler N. Improving access to adult primary care in Medicaid: Exploring 

the potential role of nurse practitioners and physician assistants. Issue paper. Washington, DC: 

Kaiser Commission on Medicaid and the Uninsured, The Henry J. Kaiser Family Foundation. 

2011.

4. Carrier ER, Yee T, Stark L. Matching supply to demand: Addressing the U.S. primary care 

workforce shortage. Policy analysis no 7. Washington, DC: National Institute for Health Care 

Reform. 2011.

5. Agency for Healthcare Research and Quality. Primary care workforce facts and stats no 3. 

AHRQ pub no 12-P001-4-EF. Rockville, MD: Agency for Healthcare Research and Quality. 
NCHS Data Brief ■ No. 151 ■ May 2014

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2012. Available from: http://www.ahrq.gov/research/findings/factsheets/

primary/pcwork3/index.html.

6. U.S. Department of Health and Human Services. The registered nurse 

population: Findings from the 2008 National Sample Survey of Registered 

Nurses. Rockville, MD: Health Resources and Services Administration, U.S. 

Department of Health and Human Services. 2010.

7. Colwill JM, Cultice JM, Kruse RL. Will generalist physician supply meet 

demands of an increasing aging population? Health Aff 27:w232–41. 2008.

8. Staiger DO, Auerbach DI, Buerhaus PI. Comparison of physician 

workforce estimates and supply projections. JAMA 302(5):1674–80. 2009.

9. Cunningham PJ. State variation in primary care physician supply: 

Implications for health reform Medicaid expansions. Research brief no 19. 

Washington, DC: Center for Studying Health System Change. March 2010.

10. Larson EH, Palazzo L, Berkowitz B, Pirani MJ, Hart LG. The 

contribution of nurse practitioners and physician assistants to generalist care 

in Washington state. Health Serv Res 38(4):1033–50. 2003.

11. Kaissi A, Kralewski J, Dowd B. Financial and organizational factors 

affecting employment of nurse practitioners and physician assistants in 

medical group practices. J Ambul Care Manage 26(3):209–16. 2003.

12. National Center for Health Statistics. NCHS urban-rural classification 

scheme for counties. Hyattsville, MD: National Center for Health Statistics. 

Available from: http://www.cdc.gov/nchs/data_access/urban_rural.htm.

13. Sirken MG, Shimizu I, French DK, Brock DB. Manual on standards and 

procedures for reviewing statistical reports. Hyattsville, MD: National Center 

for Health Statistics. 1990.

Suggested citation

Hing E, Hsiao CJ. State variability in supply 

of office-based primary care providers: 

United States, 2012. NCHS data brief, no 

151. Hyattsville, MD: National Center for 

Health Statistics. 2014.

Copyright information

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the public domain and may be reproduced 

or copied without permission; citation as to 

source, however, is appreciated.

National Center for Health 

Statistics

Charles J. Rothwell, M.S., M.B.A., Director

Jennifer H. Madans, Ph.D., Associate 

Director for Science

Division of Health Care Statistics

Clarice Brown, M.S., Director

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