Employment of Advanced Practice Clinicians in Physician Practices

Abstract

This study examines trends in advanced practice clinician employment across different physician practices in the United States.

Nurse practitioners (NPs) and physician assistants (PAs) are advanced practice clinicians that are increasingly involved in the delivery of health care services. The role of advanced practice clinicians in primary care has been described previously.^1,2,3,4 However, less is known about advanced practice clinicians in physician specialty practices.⁵ In this study, we characterize levels of and changes in advanced practice clinician employment across different physician practices in the United States in 2008 and 2016, with a particular focus on specialty practices.

Methods

We used the 2008 and 2016 SK&A outpatient provider files for our analyses. The SK&A is a proprietary data set that includes information on 90% of physician practices in the United States. We first categorized specialty practices as single medical or single surgical specialty practices (Table), examining multispecialty practices separately. We also conducted analysis on the 3 largest categories of primary care practices: family medicine, internal medicine, and pediatrics. We performed supplementary analyses for the top 10 specialties by practice counts across all years. For each practice type, we calculated the proportion of practices with an advanced practice clinician (overall and by NPs and PAs) and the percent change between 2008 and 2016. Using STATA statistical software (version 15, STATA Corp) we created choropleth maps to show variation in the state-level proportion of practices that employed advanced practice clinicians in 2016.

Table. Percent of Physician Practices With Advanced Practice Clinicians and the Percent Change From 2008 to 2016.

Variable	Total Practices, No.		Any Advanced Practice Clinician, %			Any NP, %			Any PA, %
	2008	2016	2008	2016	Change	2008	2016	Change	2008	2016	Change
Specialty practicesa	132 682	165 655	23.2	28.3	21.7	14.4	19.2	32.6	11.6	14.0	20.3
Medical specialties	87 178	109 125	20.2	23.3	15.7	13.6	16.3	19.9	8.3	9.9	19.3
Surgical specialtiesb	22 881	22 185	17.8	20.6	15.8	5.8	7.7	32.6	13.6	15.3	12.0
Multispecialty	22 623	34 345	40.5	49.0	20.9	26.3	35.5	34.9	22.4	26.1	16.4
Psychiatry	12 909	16 535	14.7	17.4	18.4	13.1	15.9	20.9	2.2	2.7	19.2
Obstetrics/gynecology	12 676	13 148	29.5	29.3	−0.7	25.3	25.3	0.2	6.1	6.5	5.7
Ophthalmology	9939	10 505	0.8	0.7	−10.8	0.3	0.3	3.7	0.6	0.5	−9.1
Cardiology	6142	8483	30.3	31.0	2.4	22.1	24.3	9.6	12.7	12.9	1.8
Orthopedic surgery	6758	7293	28.0	29.1	3.9	4.9	7.0	43.0	25.3	25.4	0.6
General surgery	6213	6400	11.2	13.8	24.0	5.4	7.6	40.1	6.6	7.5	14.6
Neurology	3814	5162	13.8	21.3	54.2	9.5	15.6	64.5	5.4	8.2	52.4
Plastic surgery	6067	4177	6.4	9.8	54.2	2.7	3.8	39.8	3.9	6.4	62.9
Dermatology	5428	6041	27.4	36.3	32.5	8.4	11.5	36.8	21.7	29.5	35.6
Gastroenterology	3873	5496	25.1	28.7	14.2	15.4	19.2	24.7	12.5	14.4	15.1
Primary care practicesc	68 317	69 755	28.4	35.3	24.3	18.8	26.1	38.8	12.5	14.6	16.8
Family practice	30 322	31 936	36.7	44.8	22.1	22.4	31.6	41.0	18.4	21.0	13.9
Internal medicine	22 514	22 424	18.3	23.9	30.8	12.0	17.6	46.2	7.7	9.3	21.3
Pediatrics	12 164	12 939	27.9	34.3	22.8	23.0	29.3	27.3	7.3	9.0	22.4

Abbreviations: NP, nurse practitioner; PA, physician assistant.

^aSpecialty practices include medical specialties: addiction medicine, adolescent medicine, aerospace medicine, allergy/immunology, anesthesiology, cardiology, critical care medicine, dermatology, dialysis, emergency medicine, endocrinology, gastroenterology, general preventive medicine, genetic specialist, gynecologic oncology, holistic medicine, infectious disease, nephrology, neurology, nuclear medicine, obstetrics/gynecology, occupational medicine, oncology/hematology, ophthalmology, otolaryngology, pain management, physical medicine/rehab, psychiatry, pulmonology, rheumatology, sleep medicine, sports medicine, urology, vascular and interventional radiology.

^bSurgical specialties include bariatrics, colorectal surgery, general surgery, head and neck surgery, neurological surgery, orthopedic surgery, plastic surgery, thoracic surgery, transplant surgery, trauma surgery, and vascular surgery.

^cPrimary care includes family practice, general practice, geriatric medicine, internal medicine, internal medicine/pediatrics, and pediatrics.

Results

In 2016, approximately 28% of all specialty practices employed advanced practice clinicians. Multispecialty practices were most likely (49%) and surgical specialties least likely (21%) to employ advanced practice clinicians. Among the top 10 specialties, advanced practice clinicians were employed in at least a quarter of practices in the following specialties: cardiology, obstetrics-gynecology, dermatology, gastroenterology, and orthopedic surgery. Specialty practices were more likely to employ NPs than PAs, with the exception of surgical practices, which relied more on PAs. Overall, from 2008 to 2016, there was a 22% increase in specialty practices employing advanced practice clinicians. As a point of comparison, there has been a 24% increase in advanced practice clinician use among primary care practices, such that 35% of these practices have at least 1 advanced practice clinician by 2016. Employment of NPs in specialty practices grew faster compared to PAs (33% vs 20% increase).

In the Figure we show that specialty practice advanced practice clinician employment was greatest in the Mountain West and West North Central regions (eg, North Dakota, South Dakota, Minnesota, and Iowa) during 2016—analogous to primary care. We also note that restricting our analyses to a balanced panel of practices from 2008 to 2016 did not meaningfully change the data patterns we observed.

Figure. Percent of Physician Practices With Advanced Practice Clinicians by State.

Conclusions

We found that about 1 in 4 specialty practices employ advanced practice clinicians, compared with 1 in 3 primary care practices. Because the NP role was historically developed to focus on primary care and most advanced practice clinicians are NPs, one would expect that advanced practice clinicians would have a greater presence in primary care practices. The proportion of practices with advanced practice clinicians grew modestly over the past 8 years and the growth was similar across specialty and primary care practices. Overall growth in advanced practice clinicians may be driven by recent increases in graduates from advanced practice clinician programs, the emergence of value-based purchasing models that are incentivizing team-based care, and downward price pressure from public and private payers—making the lower costs of advanced practice clinician employment more attractive. Advanced practice clinicians may also be increasingly moving into specialty practices as specialist physicians embrace new roles for advanced practice clinicians.⁶ These data have important limitations. They only include outpatient providers and they have no information about the specific duties of advanced practice clinicians in the practice. As the presence of advanced practice clinicians in the delivery of specialty care increases, future research will need to understand their contributions to access, quality, and value.