Preventive medicine is the medical specialty that bridges the gap between public health, population health, and clinical medicine.1 Preventive medicine specialists are licensed physicians who possess expertise in a broad range of skills beyond clinical medicine, for example, planning and evaluation of health services, epidemiology, public health practice, management, and leadership. They apply their knowledge and skills to measure and improve the health and quality of life of individuals, families, communities, and populations through disease prevention and health promotion.
The need for preventive medicine physicians has been recognized by multiple national advisory bodies and experts on the public health and medical workforce in the United States.2,3 Their training in epidemiology, administration, and policy analysis and development via the required Master of Public Health degree provides just the skills necessary to plan and coordinate preventive care in a pandemic. The need for a preventive medicine specialty, and the value of a physician workforce that can bridge the health care and public health sectors, is highlighted by the current COVID-19 pandemic. As described elsewhere in this issue, in the spring of 2020, preventive medicine trainees filled critical roles in the pandemic response, in population/public health (eg, organization of testing sites, development of tracking tools, testing protocols and contact tracing processes, surveillance, and data analysis), patient care, and medical education. Residents directly drew upon their unique training in public health and epidemiology, population health, and emergency preparedness.
Despite the value of these roles and skill sets, there is a real and significant shortage of physicians trained in preventive medicine. The most recent analysis of the preventive medicine physician supply published in 2000 demonstrated a decline in the national supply from 7734 physicians reporting a preventive medicine specialty in 1970 to 6855 in 19974 as other specialties increased their numbers and the total supply of physicians expanded. The number of preventive medicine physicians decreased from 2.1% of the total workforce in 1970 to 0.9% in 1997.4 Since 2000, there have been no published, comprehensive analyses of the preventive medicine workforce. This study uses data from 2 national data sources as well as previously published studies to determine trends in the number of American Board of Preventive Medicine (ABPM) board-certified and self-designated preventive medicine physicians. This study also provides updated data on the age and gender distribution of the workforce, as well as on the geographic location of preventive medicine physicians. These analyses were conducted by the Carolina Health Workforce Research Center for a “Rapid Response” request by the Health Resources and Services Administration's (HRSA's) (US Department of Health and Human Services [US DHHS]) National Center for Health Workforce Analysis (NCHWA).
This report uses data from 2 main data sources: the ABPM Web site5 and multiple years of the American Medical Association (AMA) Masterfile, which includes data from the American Board of Medical Specialties (ABMS).
Using the online lookup data system of the ABPM, we identified all ABPM-boarded physicians in the United States and retrieved their specialty, city, and state as of May 2019. We obtained information on all physicians boarded in 1 or more of the 3 core preventive medicine specialty areas (aerospace medicine, occupational medicine, and public health and general preventive medicine) and the 4 additional specialty areas (addiction medicine, clinical informatics, medical toxicology, and undersea and hyperbaric medicine); however, we include in this report only those individual physicians in the former group. Public health certifications were combined with general preventive medicine in tables and graphs to reflect the current ABPM classification; however, these designations remain separate for earlier cohorts (Table).
Comparison of Preventive Medicine Physicians by Board Certification and Self-designating in a Preventive Medicine Practice Specialty in 2017a
||1999 ABPM-Certified Physicians
||2019 ABPM Certifications
|Public Health and General Preventive Medicine
|General Preventive Medicine
|Subtotal: Core specialty area certifications
|Undersea and Hyperbaric Medicine
10 177 certifications
|Total certified preventive medicine physicians
9 270 physicians
Abbreviation: ABPM, American Board of Preventive Medicine.
Data from American College of Preventive Medicine, ABPM, American Board of Medical Specialties data 2020, and Lane.4
Data include only those in the 50 US states and District of Columbia. The 1999 data do not specify geographic location.
We used the 2019 AMA Masterfile with data current through 2018 to obtain data on individual physicians including ABMS certification data with board name, certification date, and expiration date, for up to 7 certifications; data on “self-designated” practice specialty (up to 2); gender and birth year; and practice location (county). The Masterfile provides an accurate, continuously updated series of data describing physicians practicing in the United States. While some researchers have noted concerns about accuracy and timeliness,6–10 it is a comprehensive source of data on all US physicians that are comparable from year to year. The analysis reflects data on active physicians younger than 80 years and excludes inactive and deceased physicians.
We classified the practice location county using Office of Management and Budget (OMB) metropolitan/nonmetropolitan (rural/urban) classifications and underserved area designations from the Area Health Resources File (AHRF) database distributed by the Bureau of Health Workforce (US DHHS).11 The US OMB classifies counties as either “Core-Based Statistical Area” (CBSA) counties—either metropolitan or micropolitan. Metropolitian counties have a central city of at least 50 000 population and may include adjacent counties where there is significant migration to the central city. Micropolitan counties are defined as those with a city of between 10 000 and 50 000 people. Noncore, or rural, counties lack a threshold urban population of 10 000. We also compared the 2017 Masterfile data with data from 2 earlier publications on preventive medicine physicians that also used the Masterfile.4,12
We defined preventive medicine physicians in 2 ways: using ABPM data for board-certified physicians and using Masterfile data for physicians who self-designate their practice specialty as preventive medicine. The latter may not be board certified. We utilized American College of Preventive Medicine (ACPM) and Doximity data to determine the most recent number of residency slots and the current number of residents to assess the training pipeline of preventive medicine physicians. Excluded from these analyses are physicians trained in preventive medicine who are neither board certified nor self-designate as a preventive medicine specialist. Figure 1 identifies the overlap of board-certified and self-designated as practicing preventive medicine physician.
The total number of active ABPM board certifications in 2018 and board-certified physicians in 1999 in preventive medicine specialties and subspecialties is presented in the Table. As some physicians hold board certification in multiple specialties or subspecialties, the data in the Table display the number of certifications in 2018 and the number of unique certified physicians in total. The 1999 data are from the earlier Lane4 study and represent the unduplicated number of ABPM-certified physicians in each specialty. In 1999, there were 6091 board-certified physicians in a preventive medicine specialty area. By 2018, a total of 9270 physicians held 10 177 ABPM board certifications. This represents a 52% increase in the number of board-certified physicians from 1999 to 2018. This growth was largely driven by the emergence of board certifications in the newer specialty areas of undersea and hyperbaric medicine, addiction medicine, and clinical information. Changes in numbers of board-certified physicians in specific core specialty areas cannot be directly compared between 2018 and 1999 in the Table because the 2018 data represent the number of certifications awarded by the ABPM while the data reported in 1999 include the number of unique individuals with an ABPM board certification. Although there exist physicians who hold dual boards in core preventive medicine specialty areas, the number of certifications in 2018 likely approximates the number of unique individuals boarded in that core specialty area. Thus, the general finding indicates that, among the 3 core specialties, there was an increase in preventive medicine physicians from 1999 to 2018 driven primarily by growth in the specialty of occupational medicine. In 1999, there were 2442 board-certified occupational medicine physicians, while in 2018, there were 3168, an increase of 30% of board-certified physicians in that subspecialty.
Figure 2 presents the number of physicians who designated preventive medicine as their practice specialty and the number per 100 000 population in the United States from 1965 to 2018. The data for the figures are drawn from multiple years of the AMA Masterfile and include the unduplicated total number of active physicians younger than 80 years who report a specialty within preventive medicine (as their first or second specialty area) as well as the number per 100 000 population from 1965 to 2018. The reported number of physicians who self-designate a practice specialty within preventive medicine varies from year to year, in part, because the Masterfile does not update information on every physician in every year nor changes in the specialty designation reported by the physicians themselves. The number of physicians who designated preventive medicine as their practice specialty reached its peak of 7734 in 1970, with 3.77 preventive medicine physicians per 100 000 people in the United States. The number of these physicians has remained relatively stable, while the ratio of preventive medicine physicians to population has fallen since 2001, reaching a low point in 2014 when there were 6415 physicians identifying their specialty as preventive medicine. There has been a slight rebound and leveling off in both the absolute number of preventive medicine physicians and the ratio per population in the years since 2014. In 2018, there were 6866 physicians who designated preventive medicine as their practice specialty, or 2.11 physicians per 100 000 people.
Figure 3 presents the age and gender population pyramids of physicians who identify as preventive medicine physicians in the Masterfile in 2001 and 2018. The more recent year's profile reveals a specialty that has become older but whose practitioners are more often female; 1842 or 24.6% of all preventive medicine physicians were female in 2001. That number rose to 2419 in 2017 or 27.05% of the total in that year, an increase in the number of females of 31.3% over 16 years. In 2001, 29% (2220/7492) of the active US preventive medicine workforce was 60 years or older; by 2017, that proportion increased to 47.1% (3208/6810). The proportion of physicians who self-designated preventive medicine as their practice specialty and who are male declined between 2001 and 2017, with females outnumbering males in the youngest age intervals in 2017. The overall proportion of physicians who are female has increased in recent years from 27.3% in 2001 to 35.4% in 2017.
There are large state-to-state variations in the distribution of board-certified preventive medicine physicians across the United States, with the highest density of preventive medicine physicians in Maryland and the District of Columbia (10.85 and 21.11 per 100 000 population, respectively), followed by Hawaii (7.2), Washington (6.08), Colorado (6.01), and Massachusetts (5.9). The states with the fewest preventive medicine physicians per population are Mississippi (1.11 per 100 000 population), Nevada (1.3), Arkansas (1.42), and Iowa (1.49).
Preventive medicine physicians are not proportionately distributed across the rural-urban geography of the United States. In 2017, only 2.0% (119/5737) of the total number of active preventive medicine physicians in the Masterfile who reported a practice address in the 50 states and the District of Columbia were in non-CBSA, or rural counties. The population in these rural counties, however, is 5.5% of the total US population. Similarly, 6.5% (377 of the total active preventive medicine physicians) were in “micropolitan” (small city) counties, which account for 8.4% of the total US population.
Data from the ACPM13 and Doximity14 indicate that there were 75 active preventive medicine residency programs accepting fellows/residents in the 3 core subspecialties as of November 2019. The Doximity data identify 313 filled slots in core specialties in early 2020. These figures suggest a decline in the number of programs and residents compared with data from the Lane4 study, which identified 90 programs with 420 residents in preventive medicine in 1999. This decline will contribute to a reduction in preventive medicine physician supply, but the proximal future supply will initially be most affected by the aging of the current workforce.
The preventive medicine workforce has been generally declining in proportion to the US population since 2000. The number of preventive medicine physicians currently being trained will not reverse this trend. The United States is reaching a point where the majority of active preventive medicine physicians will be older than 59 years. Currently, 47.1% of active preventive medicine physicians are older than 59 years; soon the 60 years and older group will be a majority and their likely retirement will accelerate the decline in the ratio of preventive medicine physicians to the population. The recent increase in the entry of women into the specialty reflects the increased number of women into medicine more generally15 and has resulted in slightly more women than men in the youngest age groups. Even with the growth of women in the preventive medicine workforce, the training pipeline is not producing enough new preventive medicine physicians to keep pace with population growth and retirements. Understanding the relationship between the number and size of training programs and the supply of physicians practicing preventive medicine is complicated by the fact that slightly less than one-half of the physicians who self-designate their specialty as preventive medicine do not have a preventive medicine board certification.
Geographically, there is little penetration of the preventive medicine physician workforce into rural areas, and the overall distribution is skewed to selected locations including academic health centers, government agencies including military posts, and research institutions.
There are limitations to the publicly available data describing the preventive medicine physician workforce. While the board certification data accurately identify physicians who sit for examinations, data on their current practice locations and their activity status may not be updated, resulting in overcounts and an inaccurate picture of their distribution. Likewise, the AMA Masterfile includes location and activity data that may lag but also the ability of physicians to “self-designate”—or not—as practicing preventive medicine creates further inaccuracy in counts.
Developing an accurate picture of the preventive medicine physician workforce is complicated by a lack of a clear way to classify and enumerate which physicians are in the specialty. The data used here to develop an assessment of the number, geographic location, practice characteristics, and activity status of the preventive medicine workforce were neither as current nor as detailed as they should be. The development of a more robust system to track these physicians from training through practice and on to retirement is needed. However, it is apparent from available data that the number of preventive medicine physicians being trained will not maintain the current supply relative to the population in the near future and there is an urgent need for expansion of training programs due to the aging profile in the specialty. This is not a new observation; the Institute of Medicine in 2007 anticipated a severe shortage and declared that the nation would see an increased requirement for preventive medicine physicians in the future.3
There is also evidence that the preventive medicine workforce needs to be more representative of the geography and demography of the nation and that training programs should focus more on rural and underserved populations and their needs.16 The “place” and “role” for preventive medicine physicians have not been well established, and policy makers and leaders within academic medicine, the broader field of medicine, public health, health care, and community care systems and networks need a better understanding of the role and contributions of preventive medicine practitioners.
There are some solutions for these challenges already in place. The federal government supports preventive medicine training and practice via several mechanisms. Public Health and Preventive Medicine Training Grant funding is available to training institutions, with $17 million appropriated in the FY2020 budget and approximately $7 million of that goes directly to preventive medicine residencies via the Preventive Medicine Residency (PMR) program operated by HRSA. In academic year 2018-2019, the PMR program financially supported 128 residents (compared with 130 in 2017-2018), the majority of whom received clinical or experiential training in a primary care setting (82%) and/or a medically underserved community (61%).17 Overall, the program supported, in 2018, close to 20% of all preventive medicine residents in training. However, the 2021 proposed HRSA budget requests no funding for these programs. Federal appropriations from Congress are a lifeline for many existing residency programs. Its loss would reduce the number of new preventive medicine specialists being trained and cause a decline in the overall supply of preventive medicine specialists. It would also result in a leadership gap in public health and prevention in the United States that would last well into the future. Determining how big that gap would be depends on more sophisticated workforce analysis of the current supply of preventive medicine specialists and the demand for them.
Key leaders in preventive medicine have been vocal in their arguing for enhancing the quantity, quality, and distribution of preventive medicine specialists1,18–21 and have suggested that their categorization be expanded beyond formal residency programs to some form of privileging supported by preventive medicine physiciansʼ formal training in the key disciplines of epidemiology, biostatistics, and management/administration combined with necessary expertise in the core public health competencies of assessment and research, policy development, and assurance. This could be accomplished through development of more rigorous standards of practice for preventive medicine specialists.21,22 This approach may allow for some expansion of the numbers of preventive medicine specialists but is unlikely to meet the recognized overall national need for as many as twice the current number.2,3
Multiple threats to health in the United States caused by environmental conditions and the emergence of new diseases such as the COVID-19 virus are growing. Likewise, the need for well-trained preventive medicine physicians to confront these challenges grows apace.
Implications for Policy & Practice
- This article describes the demography of preventive medicine specialists in the United States and reveals a growing shortage of these practitioners and a maldistribution that disproportionately affects underserved, especially rural populations.
- The population and geographic needs for PM physicians, especially in rural and underserved areas and institutions should be determined and programs that encourage practice in those institutions and communities developed and/or expanded.
- The numbers of preventive medicine physicians being trained will not meet demands for their services and skills in the future and current programs need to be expanded.
- The diversity of the PM workforce is currently unknown. Data from 2005 for active physicians with a primary specialty of preventive medicine included 392 (4.1%) who self-identified as “Black-Non-Hispanic”, 260 (2.7%) as Hispanic, and 5 Native Americans (<0.01%).
- PM training programs should be encouraged to recruit, retain and graduate preventive medicine physicians who more closely match the racial and ethnic diversity of the communities they serve.
- The importance of the skillset that is part of preventive medicine training and practice, including training in epidemiology, management and policy, has been highlighted by the COVID pandemic and the specialty should refine and expand this alignment in the context on ongoing population health needs.
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