Analysis of Trends in Geographic Distribution of US Dermatology Workforce Density

Abstract

This study examines the geographic distribution of the US dermatology workforce density using data from the American Academy of Dermatology and the Society for Dermatology Physician Assistants.

The demand for dermatologic care is rising. Dermatologist density in the Unites States has increased over the past decade and is currently estimated at 3.4 per 100 000 individuals. However, it is still below the suggested 4 per 100 000 population needed to adequately care for a community. Increased dermatologist density has been associated with lower melanoma mortality rates and improved diagnosis of skin disease. Therefore, dermatologist density is of critical importance and may lead to lower skin disease economic burden.

In addition to the undersupply, there is also a material geographic variance of dermatologists throughout the United States leaving some areas underserved. Dermatologists are now being supplemented by nonphysician clinicians which may help to correct for the dermatology provider shortage. The purpose of this study was to examine the combined geographic distribution of dermatologists and dermatology physician assistants (DPAs) to determine overall dermatology provider density and how this combination may potentially be augmenting access.

Methods

Membership data and geographic data on practicing dermatologists and DPAs were obtained from the American Academy of Dermatology (AAD) and the Society for Dermatology Physician Assistants (SDPA). The data were combined and total dermatology provider-to-population ratios were calculated using population data obtained from the US Census Bureau for 3-digit ZIP code locations (section codes). Adjacent section codes were combined where appropriate. Institutional review board approval was waived because this study did not report on data involving human subjects.

Results

The 2016 total number of dermatology providers was 13 365 (10 845 dermatologists and 2520 DPAs) yielding an overall density of 4.14 per 100 000 individuals. Of the 734 section codes containing at least 1 dermatology provider, 22 (3%) contained only DPAs. By including DPA coverage, the number of section codes containing less than 3 dermatology providers per 100 000 individuals decreased from 59.8% to 47.4% when accounting for dermatologists alone. With the combined data, the percentage of section codes containing greater than 4 providers per 100 000 increased from 27.7% to 40.2%. Overall, 35.0% of dermatology providers practiced in the 100 densest section codes compared with just 1.5% in the 100 least dense section codes. Differences between data on physicians only vs total dermatology providers are summarized in the Table.

Table. Changes in Dermatology Provider Density for the Addition of DPAs^a.

Variable	Dermatologists Only	DPAs Only	Total Dermatology Providers	Change From Dermatologists Only to Total Dermatology Providers, %
Dermatology providers, No.	10 845	2520	13 365	+23.2
Dermatology providers per 100 000 persons	3.36	0.78	4.14	+23.2
Section codes serviced, No.	712	561	734	+3.1
Section codes with more than 4 dermatology providers, %	27.7	1.7	40.2	+12.5
Section codes with fewer than 3 dermatology providers, %	59.8	95.4	47.4	-12.4
Dermatology providers in 100 most dense section codes, %	38.6	28.2	35	-3.6
Dermatology providers not in 100 most or least dense areas, %	59.6	64.5	63.5	+3.9

Abbreviation: DPAs, dermatology physician assistants.

^aChanges show the comparison between dermatologist, DPA, and total dermatology provider density and percent change to the total dermatology provider pool with the addition of DPAs.

Discussion

Including DPAs in dermatology workforce calculations increases the average US dermatology provider density to more than 4 per 100 000 individuals, which is the number that has been suggested to adequately care for a population. Dermatologists and DPAs in the United States are both nonuniformly geographically distributed. However, dermatologists tend to be more concentrated in major urban areas and academic centers vs DPAs in somewhat less populous regions. Analysis of the distribution combining both groups therefore leads to a broader, more uniform coverage and potentially extends access (Figure). Adding DPAs to the dermatology provider pool augments care away from the 100 most dense section codes suggesting that DPAs may extend care benefit to communities that were previously underserved.

Figure. US Dermatology Provider Density by 3-Digit ZIP Code.

The number of dermatology providers practicing per 100 000 people in each 3-digit postal section code is indicated by the colors on the map. Section codes without a dermatology provider are included in white. Note that the Great Lakes are included in US section coding and do not appear on the map.

Dermatologists alone have been unable to meet increasing patient demand for dermatologic services. The number of dermatology residency training positions has been relatively stagnant, suggesting that the current supply of dermatologists in training will be insufficient to fully meet growing future demand. This gap is being filled in part by a substantial of influx of physician assistants into the field of dermatology. The increasing numbers of physician assistant training programs and slots coupled with shorter required training periods for physician assistants suggest a continuation of this trend in the dermatology workforce provider mix. However, to better correct the geographic maldistribution and its impact on access, initiatives may need to be developed that will incentivize both dermatologists and DPAs to relocate to underserved regions.