Key Points
Question
How many dermatology visits are provided by advanced practice clinicians (APCs, including nurse practitioners and physician assistants) compared with physicians and how has this changed over time?
Findings
In this retrospective cohort study using the Medicare Public Use Files, a method to identify APCs in dermatology was developed and validated. A total of 8444 dermatology APCs and 14 402 physician dermatologists were identified. The percentage of dermatology clinicians who were APCs increased over time, as did the percentage of office visits by dermatology APCs.
Meaning
These findings demonstrate changes in the dermatology workforce and may have implications for dermatology as a specialty.
Abstract
Importance
The number of advanced practice clinicians (APCs, including nurse practitioners and physician assistants) in the US is increasing. The effect this has on dermatology is unclear.
Objective
To develop a method to identify APCs practicing dermatology in claims data and to evaluate the contribution of dermatology APCs to the dermatology workforce and how this has changed over time.
Design, Setting, and Participants
This retrospective cohort study used the Medicare Provider Utilization and Payment Data Public Use files (2013 to 2020). As APCs are not listed by specialty, a method to identify APCs practicing dermatology was developed and validated using common dermatology procedural codes. The data were analyzed from November 2022 to April 2023.
Main Outcomes and Measures
The proportion of clinicians and office visits by dermatology APCs and physician dermatologists were evaluated using Mann-Kendall tests. Joinpoint analysis was also used to compare the average annual percentage change of dermatology procedures and clinicians in rural-urban areas between dermatology APCs and physician dermatologists.
Results
The method to identify APCs practicing dermatology had 96% positive predictive value, 100% negative predictive value, 100% sensitivity, and 100% specificity. Between 2013 and 2020, 8444 dermatology APCs and 14 402 physician dermatologists were identified. They provided 109 366 704 office visits in Medicare. The percentage of dermatology clinicians who were APCs increased over time, from 27.7% in 2013 to 37.0% in 2020 (P = .002). The proportion of dermatologic office visits provided by APCs also increased over time, from 15.5% in 2013 to 27.4% in 2020 (P = .002). For all procedure categories, the average annual percentage change was positive for dermatology APCs (range, 10.05%-12.65%) and was higher than that of physician dermatologists. For all rural-urban designations, the average annual percentage change was positive for dermatology APCs (range, 2.03%-8.69%) and was higher than metropolitan, micropolitan, and small-town areas from that of physician dermatologists.
Conclusions and Relevance
In this retrospective cohort study, there was a temporal increase in the amount of dermatologic care provided by APCs in Medicare. These findings demonstrate changes in the dermatology workforce and may have implications for dermatology as a specialty.
This cohort study evaluates the contribution of advanced practice clinicians, including nurse practitioners and physician assistants, to the dermatology workforce and how this has changed over time.
Introduction
The number of advanced practice clinicians (APCs, including nurse practitioners and physician assistants) in the US has increased. Research has suggested that APCs have become a growing presence within subspecialties, and researchers have noted an increase in dermatologic procedures performed by APCs.1,2 However, prior studies have not directly identified APCs in dermatology and have focused solely on procedures.3,4 The participation of dermatology APCs in overall dermatologic care, including office visits, has yet to be explored.
The APCs joining the dermatology workforce could be beneficial to patient access. The American Academy of Dermatology has identified an unmet need for dermatologic services related to a demand for dermatology that is not coinciding with an increase in the supply of physician dermatologists. This unmet need may be exacerbated by physician dermatologists favoring urban areas.5 Though this presents an opportunity for dermatology APCs to improve access, dermatology APCs have also been reported to practice in mostly urban areas.6,7 These patterns have consequences, as dermatologist density is associated with improved patient outcomes for skin disease, including melanoma.8,9,10
Methods
We performed a retrospective cohort study using the publicly available Medicare Provider Utilization and Payment Data Public Use Files (2013 to 2020).11 This study was not required for review by the MD Anderson Cancer Center institutional review board because the data were publicly available and contained only aggregated, nonidentifiable patient information. The data were analyzed from November 2022 to April 2023.
Identification of Physician Dermatologists and Dermatology APCs
We identified physician dermatologists as MD and DO clinicians with a specialty in dermatology. Because APCs are not listed by specialty, we developed a method to identify APCs likely practicing dermatology. We first generated a list of procedure codes based on previously published studies of common dermatologic procedures.3,4 We then excluded procedures that were less specific to dermatology, such as the simple repair, often used in emergency medicine (final code list in eTable 1 in Supplement 1). We considered APCs to be dermatology APCs if they were listed as a nurse practitioner or physician assistant and if they also billed at least 1 CPT code in the determined code list. To validate this approach, we conducted internet searches of 500 APCs from the 2020 Medicare Public Use Files to establish as a reference standard whether they described their practice as dermatology (100 APCs we did not classify as dermatology APCs, 100 APCs we did classify as dermatology APCs, and 300 were randomly selected APCs). We evaluated the sensitivity, specificity, positive predictive value, and negative predictive value of the method that we developed.
Statistical Analysis
We evaluated the proportion of clinicians and office visits by dermatology APCs and physician dermatologists. We evaluated trends over time using Mann-Kendall tests, which assess whether there is a monotonic increasing or decreasing trend over time, and additionally reported the Kendall τ-b correlation coefficient values, which measure the monotony of the slope.
Using Joinpoint analysis,12 we calculated the average annual percentage change of the counts of dermatology procedures (eTable 2 in Supplement 1 for code list) performed by dermatology APCs and physician dermatologists. We also calculated the average annual percentage change of the counts of dermatology APCs and physician dermatologists in different rural-urban designations, using the US Census Bureau’s rural-urban commuting area codes.13 For both procedures and rural-urban designations, we compared the average annual percentage changes for dermatology APCs and physician dermatologists using pairwise comparison tests for parallelism.
Finally, because the year 2020 may have been influenced by the COVID-19 pandemic, we performed a sensitivity analysis that excluded data from 2020. All tests were 2-sided with P < .05 as the significance threshold. The statistical software used was the Joinpoint Regression Program, version 5.0 (Statistical Methodology and Applications Branch, Surveillance Research Program, National Cancer Institute).
Results
Validation of Method to Identify Dermatology APCs
Using the present study’s method for identifying dermatology APCs, there was a 96% positive predictive value (based on 100 APCs who were classified as dermatology APCs: 4 false positives, 96 true positives), 100% negative predictive value (based on 100 APCs that were not classified as dermatology APCs: 0 false negatives, 100 true negatives), and 100% sensitivity and specificity (based on 300 randomly selected APCs: 0 false negatives, 0 false positives, 6 true positives, 294 true negatives).
A total of 8444 dermatology APCs and 14 402 physician dermatologists were identified in the 2013 to 2020 Medicare Public Use Files. They provided 109 366 704 office visits.
Clinicians and Office Visits
Of the 22 846 dermatology clinicians (dermatology APCs and physician dermatologists), the percentage who were APCs increased over time (P for trend = .002; Kendall τ-b = 1; P < .001 indicating a perfect positive monotonous association; Figure, A); the percentage of APCs was 27.7% in 2013 and 37.0% in 2020. Of the 109 366 704 office visits by dermatology clinicians, the percentage that was provided by APCs increased over time (P for trend = .002; Kendall τ-b = 1; P < .001; Figure, B); the percentage provided by APCs was 15.5% in 2013 and 27.4% in 2020.
Figure. Physician vs Advanced Practice Clinician (APC) Breakdown in Dermatology by Practitioners and Office Visits.
A, This graph shows the trends over time in dermatology clinician demographics from 2013 to 2020. The shading represents whether the practitioner was an APC (eg, a nurse practitioner or physician assistant) or whether they were a Doctor of Medicine (MD) or Doctor of Osteopathic Medicine (DO). B, This graph shows the trends over time for dermatology clinician office visits from 2013 to 2020 and whether the practitioner was an APC or MD/DO.
Dermatology Procedures
A total of 257 929 528 dermatologic procedures were identified (Table 1). Most procedures were performed by physician dermatologists (>80%). The mean annual percentage change was statistically significantly positive for dermatology APCs for all 3 procedure categories (range, 10.05%-12.65%), while the percentage change of physician dermatologists was negative (−1.49%; 95% CI, −2.52% to −0.30% for skin biopsy) or not statistically significant. All procedure average annual percentage changes of dermatology APCs were different from those of physician dermatologists (all 3 Joinpoint tests for parallelism were statistically significant; Table 1).
Table 1. Dermatology Procedures, 2013-2020.
| Procedure | Total procedures, No. (%) | Average annual percentage change (95% CI)a | P value for parallelismb |
|---|---|---|---|
| Destruction of premalignant lesions | 198 237 423 | NA | .006c (not parallel) |
| Physician dermatologists | 162 534 780 (82.0) | −1.44 (−3.26 to 0.69) | |
| Dermatology APCs | 35 702 643 (18.0) | 12.65 (11.18 to 14.94)c | |
| Skin biopsy | 36 786 358 | NA | <.001c (not parallel) |
| Physician dermatologists | 29 775 162 (80.9) | −1.49 (−2.52 to −0.30)c | |
| Dermatology APCs | 7 011 196 (19.1) | 11.79 (10.12 to 14.17)c | |
| Otherd | 21 996 747 | NA | <.001c (not parallel) |
| Physician dermatologists | 19 992 794 (90.9) | −0.78 (−2.3 to 1.06) | |
| Dermatology APCs | 2 003 953 (9.1) | 10.05 (8.42 to 12.63)c |
Abbreviation: NA, not applicable.
Average annual percentage change calculated using Joinpoint analysis on procedure counts over time; statistically significant results indicate that the average annual percentage change is statistically significantly different from 0.
P value for parallelism compares physician dermatologists to dermatology APCs and is calculated using Joinpoint pairwise analysis on procedure counts over time; statistically significant results indicate that the 2 Joinpoint regression mean functions (which are used to calculate the average annual percentage change) are not parallel.
Statistically significant values are noted.
Destruction of premalignant lesions and skin biopsy accounted for more than 90% of the total procedures. All other procedures were grouped in a single category. Includes simple repair, intermediate repair, complex repair, skin grafts, adjacent tissue transfer, destruction of malignant lesions, shaving of skin lesions, excision of malignant lesions, and excision of benign lesions.
Rural-Urban Designations
From 2013 to 2020, 91.1% of dermatology clinicians practiced in metropolitan areas (Table 2). Outside of metropolitan areas, there were more dermatology APCs than physician dermatologists, ranging from 55.6% in micropolitan areas to 87.8% of the total in rural areas. The average annual percentage change was statistically significantly positive for dermatology APCs for all rural-urban designations (range 2.03%-8.69%), while the percentage change of physician dermatologists was statistically significantly positive for metropolitan and micropolitan areas (1.62%; 95% CI, 1.46%-1.79% and 1.12%; 95% CI, 0.50%-1.75%, respectively). The percentage change was not statistically significant for small-town and rural areas. For metropolitan, micropolitan, and small-town areas, average annual percentage changes of dermatology APCs were different from those of physician dermatologists (all 3 Joinpoint tests for parallelism were statistically significant; Table 2).
Table 2. Rural-Urban Area Distribution of Dermatology Clinicians, 2013-2020a.
| Area | Mean No. of clinicians per year (%) | Average annual % change (95% CI)b | P value for parallelismc |
|---|---|---|---|
| Metropolitan | 15 549 | NA | .006d (not parallel) |
| Physician dermatologists | 10 779 (69.3) | 1.62 (1.46 to 1.79)d | |
| Dermatology APCs | 4770 (30.7) | 8.69 (8.31 to 9.12)d | |
| Micropolitan | 1118 | NA | .01d (not parallel) |
| Physician dermatologists | 497 (44.4) | 1.12 (0.50 to 1.75)d | |
| Dermatology APCs | 621 (55.6) | 6.49 (5.56 to 7.57)d | |
| Small town | 261 | NA | .03d (not parallel) |
| Physician dermatologists | 69 (26.2) | −0.15 (−0.78 to 0.56) | |
| Dermatology APCs | 193 (73.8) | 2.03 (0.77 to 3.70)d | |
| Rural area | 109 | NA | .14 (parallel) |
| Physician dermatologists | 13 (12.2) | 1.92 (−1.07 to 5.92) | |
| Dermatology APCs | 96 (87.8) | 4.70 (2.34 to 7.37)d |
Abbreviation: NA, not applicable.
Census regions and divisions of the US defined by the US Census Bureau,13 excludes 251 clinicians from an unknown Census bureau.
Average annual percentage change calculated using Joinpoint analysis on procedure counts over time; statistically significant results indicate that the average annual percentage change is statistically significantly different from 0.
P value for parallelism compares physician dermatologists to dermatology APCs and is calculated using Joinpoint pairwise analysis on procedure counts over time; statistically significant results indicate that the 2 Joinpoint regression mean functions (which are used to calculate the average annual percentage change) are not parallel.
Statistically significant values are noted.
Sensitivity Analysis
A sensitivity analysis that excluded data from 2020 found similar results for clinician numbers, office visits, procedures, and rural-urban areas (see eTables 3 and 4 in Supplement 1 for the full results).
Discussion
In this retrospective cohort study, we developed and validated a method to determine if an APC primarily practices dermatology care in Medicare claims. From 2013 to 2020, the proportion of dermatology clinicians that were APCs and the proportion of dermatologic office visits provided by APCs increased significantly. By 2020, more than 1 in 4 dermatology visits for patients with Medicare were delivered by APCs.
We found that the number of dermatologic procedures performed by APCs increased significantly over time compared with physician dermatologists, adding further evidence to support prior literature.2 A previous study focusing on actinic keratosis destructions reported an increase in the proportion billed by APCs from 4.0% in 2007 to 13.5% in 2015.14 We found that, like physician dermatologists, most dermatology APCs practice in metropolitan areas. This is consistent with previous reports, which have found that most independently billing APCs practice in counties with higher dermatologist densities.15 Notably, however, outside of metropolitan areas, there are more dermatology APCs than physician dermatologists.
Limitations
First, Medicare Public Use Files contain only Medicare beneficiaries and may not be nationally representative. In addition, it is also possible some of the included APCs do not specialize in dermatology. However, the positive predictive value for identifying dermatology APCs was 96%.
Conclusions
In this retrospective cohort study, we report a temporal increase in the amount of dermatologic care provided by APCs in Medicare. These findings demonstrate changes in the dermatology workforce and may have implications for dermatology as a specialty.
eTable 1. Code list to identify dermatology APPs
eTable 2. Dermatology procedures
eTable 3. Dermatology procedures: 2013-2019
eTable 4. Rural-urban area distribution of dermatology providers: 2013-2019
Data Sharing Statement
References
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
eTable 1. Code list to identify dermatology APPs
eTable 2. Dermatology procedures
eTable 3. Dermatology procedures: 2013-2019
eTable 4. Rural-urban area distribution of dermatology providers: 2013-2019
Data Sharing Statement
