The Physician Workforce Active in Vascular Health Care

Vascular health care involves the treatment of patients with diseases of the arteries and veins. Traditionally, arterial diseases involving the heart (coronary artery disease) and the head (intracranial disease) are considered separately. Arterial disease affecting other parts of the body, together with venous disease, is commonly referred to as “peripheral vascular disease.” Because it affects predominantly older persons, peripheral vascular disease is a major health problem for the Medicare population.

Peripheral vascular disease includes a wide range of conditions, many of which are treated by primary care physicians and specialists alike. “Major vascular surgery,” primarily the domain of cardiothoracic, general, and vascular surgeons, includes the surgical treatment of three common conditions:

• Carotid artery disease involves atherosclerotic narrowing of the main arteries of the neck supplying blood to the brain. To reduce the risk of stroke associated with this condition, many patients undergo carotid endarterectomy, a surgical procedure in which the narrowing is removed from the artery.
• Abdominal aortic aneurysm is a localized enlargement of the aorta, the main artery supplying blood to the abdominal organs and lower extremities. Large aneurysms can rupture, causing internal bleeding and frequently death. Surgical treatment—performed either prophylactically or after rupture—involves replacing the aneurysm with a synthetic bypass graft.
• Lower extremity arterial occlusive disease, also caused by atherosclerosis, refers to narrowing or blockage in the arteries supplying blood to the legs and symptoms related to inadequate circulation. Although treatment often requires a surgical bypass, less-invasive interventional procedures (e.g., balloon angioplasty) are becoming increasingly used.

In this edition of the Atlas, “major vascular surgery” refers to aneurysm repair, endarterectomy, and arterial bypass operations for peripheral vascular disease. “Other vascular surgery” refers to hemodialysis access, blood clot removal, treatment of vascular trauma, major amputation, and varicose vein surgery. “Interventional procedures” refer to the catheter-based techniques of balloon angioplasty, stent placement, vena cava filters and thrombolysis. These definitions are described in detail in the Appendix on Methods.

Subsequent chapters describe workforce issues related to specific procedures. In this chapter we focus on the delivery of major vascular surgery. Because of the importance of these issues for workforce planning, we first examine characteristics of surgeons performing major vascular surgery, including their specialties and procedural volumes. We then describe geographic variation in the supply of surgeons performing major vascular surgery. Incorporating these parameters into a workforce model developed for the Atlas, we make population-based projections concerning future workforce requirements in vascular surgery. Finally, we describe the characteristics of physicians performing other vascular surgery and interventional procedures.

Cardiothoracic and general surgeons were identified based on an analysis of procedures for which they submitted claims to the Medicare program. Vascular surgeons were defined based on board-certification data. “Clinically active” physicians were defined as those meeting a minimum threshold of clinical activity measured in relative value units. The population count is the Claritas estimate for 1996. The estimates of physicians allocated to populations take into account patient migration across the boundaries of hospital referral regions, and have been adjusted for age and sex differences in the populations (see the Appendix on Methods).

Specialists Performing Major Vascular Surgery

Several types of surgical specialists perform major vascular surgery. General surgeons receive five years of surgical residency training following medical school. Their training is broad, encompassing surgery for the abdomen, breast, head and neck, endocrine system, surgical oncology, trauma, and critical care, as well as vascular disease. Cardiothoracic surgeons receive two years of additional surgical training following the completion of general surgery residency, focused primarily on heart surgery. Vascular surgeons, certified by the American Board of Surgery since 1982, receive one additional year of training after general surgery residency, focused on peripheral vascular disease. Neurosurgeons, whose contribution to major vascular surgery is largely limited to carotid endarterectomy, are trained in programs distinct from these other specialists.

Board-certified vascular surgeons performed 39% of major vascular surgical procedures in Medicare patients in 1996 (Figure 1.1). In the same year, cardiothoracic surgeons and general surgeons each performed 29% of these procedures. The proportion of major vascular procedures performed by the three specialty groups varied markedly across geographic regions. From 1993 to 1996, the proportion of major vascular operations performed by board-certified vascular surgeons increased modestly, from 35% to 39%.

Figure 1.1.

Proportion of Major Vascular Surgery Performed by Vascular Surgeons, Cardiothoracic Surgeons, General Surgeons, and Neurosurgeons (1996). Numbers of Medicare enrollees undergoing surgery by each type of surgeon are in parentheses.

Map 1.1.

Specialty Type of Surgeon Performing the Plurality of Major Vascular Procedures in Each Hospital Referral Region (1996). Cardiothoracic surgeons performed a larger proportion of procedures in the South and Rocky Mountain West, while vascular surgeons (more...)

Procedure Volume of Surgeons Performing Major Vascular Surgery

Of all surgeons performing at least two major vascular procedures in Medicare enrollees in 1996, 1,450 were vascular surgeons, 2,792 were cardiothoracic surgeons, 4,059 were general surgeons, and 598 were neurosurgeons. These numbers represent approximately 87% of all board-certified vascular surgeons, 65% of all cardiothoracic surgeons, 20% of all general surgeons, and 16% of all neurosurgeons. While most vascular surgeons and cardiothoracic surgeons performed major vascular surgery, only a small proportion of general and neurosurgeons did so.

Surgeon volume—the average number of major vascular operations a surgeon performs each year—varies according to specialty type. Among surgeons performing at least two major vascular procedures in 1996, vascular surgeons performed on average 63 major vascular operations in Medicare enrollees, compared to averages of 25 by cardiothoracic surgeons and 17 by general surgeons. Although these estimates do not account for procedures performed in non-Medicare populations, they describe the relative volumes of the three types of surgical specialists (Figure 1.2).

Figure 1.2.

Procedure Volume Distributions of Vascular, Cardiothoracic, and General Surgeons (1996). On average, vascular surgeons had higher procedure volumes (number of major vascular procedures in Medicare patients) than cardiothoracic and general surgeons. Only (more...)

High-volume surgeons (those performing 50 or more procedures in 1996) treated 53% of all Medicare patients undergoing major vascular surgery. This proportion varied widely by hospital referral region.

Map 1.2.

Proportion of Major Vascular Procedures Performed by High Volume Surgeons (1996). The proportion of procedures performed by high-volume surgeons varied widely by hospital referral region. Broadly, the likelihood that a high volume surgeon would treat (more...)

Supply of Surgical Specialists Performing Major Vascular Surgery

In 1996, the supply of clinically active surgeons performing major vascular surgery was 2.9 per 100,000 residents. However, surgeon supply varied widely among hospital referral regions, from 1.0 to 6.2 per 100,000 residents. Regions with the highest number of surgeons performing major vascular surgery included Bend, Oregon (6.2); Alexandria, Louisiana (6.1); Hickory, North Carolina (5.7); Redding, California (5.7) and Slidell, Louisiana (5.7). Those with the lowest supply were San Jose, California (1.0); Rochester, Minnesota (1.1); Temple, Texas (1.2); Grand Junction, Colorado (1.3) and Gainesville, Florida (1.3).

Regional variation in surgeon supply is in part confounded by regional differences in the specialties of surgeons performing major vascular surgery and differences in procedure volume by specialty type. These estimates reflect the total supply of surgeons available to perform major vascular surgery.

Figure 1.3.

Clinically Active Vascular, Cardiothoracic, and General Surgeons Performing Major Vascular Surgery Allocated to Hospital Referral Regions (1996). The number of clinically active surgeons performing major vascular surgery varied from 1.0 to 6.2 per 100,000 (more...)

Map 1.3.

Total Supply of Clinically Active Vascular, Cardiothoracic, and General Surgeons Performing Major Vascular Surgery (1996). Surgeon supply was at least 30% higher than the national average in 73 hospital referral regions; 54 regions had rates more than (more...)

Board-Certified Vascular Surgeons Performing Major Vascular Surgery

The average supply of clinically active vascular surgeons performing major vascular surgery was 0.51 per 100,000 residents; local rates varied from 0.02 to 1.61 per 100,000 residents of hospital referral regions. Regions with the highest numbers of board-certified vascular surgeons included Kalamazoo, Michigan (1.61); Flint, Michigan (1.29); New Brunswick, New Jersey (1.29); Manchester, New Hampshire (1.25) and Mobile, Alabama (1.25). Those with the lowest supply were El Paso, Texas (0.02); Fort Smith, Arkansas (0.02); Tulsa, Oklahoma (0.03); Provo, Utah (0.04) and Grand Junction, Colorado (0.04).

Figure 1.4.

Clinically Active Board-Certified Vascular Surgeons Allocated to Hospital Referral Regions (1996). Adjusted rates of clinically active vascular surgeons (those who performed at least two major vascular procedures in the year) varied from 0.02 to 1.61 (more...)

Map 1.4.

Total Supply of Board-Certified Vascular Surgeons Performing Major Vascular Surgery (1996). The supply of board-certified vascular surgeons was higher in the eastern half of the United States than in the western part of the country. Surgeon supply was (more...)

Cardiothoracic Surgeons Performing Major Vascular Surgery

For the entire United States, the supply of clinically active cardiothoracic surgeons performing major vascular surgery was 0.96 per 100,000 residents. However, this rate varied from 0.04 to 3.18 per 100,000 residents among hospital referral regions. Regions with the highest numbers of cardiothoracic surgeons performing major vascular surgery included Houma, Louisiana (3.18); Terre Haute, Indiana (3.06); San Angelo, Texas (3.02); Panama City, Florida (2.91) and Slidell, Louisiana (2.70). Those with the lowest supply were Santa Rosa, California (0.04); Worcester, Massachusetts (0.04); Tacoma, Washington (0.07); Salem, Oregon (0.08) and Green Bay, Wisconsin (0.12).

Figure 1.5.

Clinically Active Cardiothoracic Surgeons Allocated to Hospital Referral Regions (1996). The supply of clinically active cardiothoracic surgeons (those who performed at least two major vascular procedures in the year) varied from 0.04 to 3.18 per 100,000 (more...)

Map 1.5.

Total Supply of Clinically Active Cardiothoracic Surgeons Performing Major Vascular Surgery (1996). Although the supply of cardiothoracic surgeons performing major vascular surgery varied widely, there was no distinct geographic pattern. Surgeon supply (more...)

General Surgeons Performing Major Vascular Surgery

The average supply of clinically active general surgeons performing major vascular surgery was 1.39 per 100,000 residents, but this rate varied from 0.02 to 4.03 per 100,000 residents among hospital referral regions. Regions with the highest numbers of general surgeons performing major vascular surgery included Bend, Oregon (4.03); Alexandria, Louisiana (3.98); Redding, California (3.84); Traverse City, Michigan (3.84) and Petoskey, Michigan (3.79). Those with the lowest supply were Ogden, Utah (0.02); Beaumont, Texas (0.10); Provo, Utah (0.11); Temple, Texas (0.11) and Rochester, Minnesota (0.21).

Figure 1.6.

Clinically Active General Surgeons Performing Major Vascular Surgery Allocated to Hospital Referral Regions (1996). Adjusted rates of clinically active general surgeons (those who performed at least two major general procedures in the year) varied from (more...)

Map 1.6.

Total Supply of Clinically Active General Surgeons Performing Major Vascular Surgery (1996). The supply of clinically active general performing major vascular surgery was at least 30% higher than the national average in 96 regions; 97 regions had rates (more...)

Projections of the Future Supply of Board-Certified Vascular Surgeons

The challenge in physician workforce planning is to understand not only the current relationship between the supply of physicians and the needs of the population, but also how they will change in the future. The physician workforce active in patient care is determined by the number of new physicians entering the workforce, the number of physicians who retire or die, and the number involved in activities other than clinical care, such as teaching, research, and administration.

In this section we model the future supply of vascular surgeons based on the current supply, the current number of trainees, and physician death and retirement rates from the Bureau of Health Professions. The projections account for growth in the population using United States Census population projections.

One of the major predictable changes that will affect the “need” for physicians in the future is the disproportionate growth in the elderly population. In order to account for these changes, the projections are adjusted for the age and sex distributions of future populations—the same adjustments used to adjust the estimates of the size of the current workforce. The projections are also adjusted for changing demographics of the physician workforce using age specific rates of hours worked per week, according to the Bureau of Health Professions.

Approximately 97 surgeons complete postgraduate medical training in vascular surgery each year. Of these, an estimated 87 would be expected to be clinically active in vascular surgery in the United States. This is based on an analysis of previous trainees, where 10% enter research, administration, or return to their native country, and thus do not actively practice vascular surgery. Assuming that this level remains constant, the unadjusted vascular surgery workforce will grow over the next 25 years, stabilizing at about 2,700 surgeons. Adjustments for changes in population age and the reduced workload of an aging physician workforce change this prediction slightly. On an age-adjusted basis, the supply of vascular surgeons will increase over the next fifteen years, from 0.5 to 0.7 per 100,000 residents, and then stabilize (Figure 1.7).

Figure 1.7.

Projected Supply of Vascular Surgeons Adjusted for Population and Workforce Demographic Changes (1995-2020). The model predicts the size of the vascular surgery workforce, adjusted for population growth (blue line) and for differences in age of the professional (more...)

What would be necessary to either reduce the oversupply of vascular surgeons predicted by a low-rate benchmarks, or increase the workforce to conform with the rates in areas at the high end of the distribution? If the number of vascular surgery training positions were cut in half, it would be well over 25 years before the national supply of vascular surgeons declined to the current level of the Miami hospital referral region (Figure 1.8). On the other hand, even if the number of training positions were doubled, the national supply of vascular surgeons in 25 years would still not be equal to the level currently available to residents of the Kalamazoo, Michigan hospital referral region.

Figure 1.8.

Projected Supply of Vascular Surgeons (1995-2025). The figure compares the effects of halving or doubling the current number of graduate medical training positions in vascular surgery against current benchmarks for low supply of vascular surgeons (Miami) (more...)

Projections of the Total Vascular Surgery Workforce

Because other surgical specialists perform vascular surgery, the total effective vascular surgery workforce is much greater than the supply of board-certified vascular surgeons. Procedural volume varies widely according to surgeon specialty. Vascular surgeons perform more major vascular procedures, on average, than cardiothoracic and general surgeons.

For workforce projections, it is also important to consider the relative contributions of surgeons in different age groups, which varies according to specialty. Among younger surgeons, a much greater proportion of major vascular operations is performed by board-certified vascular surgeons. Of major vascular procedures performed in 1996 by surgeons younger than 45 years old, 49% were done by vascular surgeons, 22% by cardiothoracic surgeons, and 26% by general surgeons (Figure 1.9). In contrast, of procedures performed by surgeons who were more than 55 years old, 28% were performed by vascular surgeons, 42% by cardiothoracic surgeons and 27% by general surgeons.

Figure 1.9.

Proportion of Major Vascular Procedures Performed by Vascular, Cardiothoracic, and General Surgeons, as a Function of Surgeon Age. Among those performing major vascular surgery, younger surgeons are more likely to be board-certified vascular surgeons (more...)

To account for these differences in practice patterns by surgeon age in the model, we calculated the total proportion of all major vascular operations performed by certified vascular surgeons in each five-year age group, and used this proportion to estimate the total effective vascular surgery workforce. Assuming these proportions remain constant over time, the growth in the total effective vascular surgery workforce will be slower than the growth in the supply of board-certified vascular surgeons as older general and cardiothoracic surgeons, who currently perform a large proportion of vascular procedures, retire and are not replaced. Thus, the total effective vascular surgery workforce is projected to grow by about 15% over the next 10 to 15 years, and then return to current levels by the year 2020 (Figure 1.10).

Figure 1.10.

Projected Total Vascular Surgery Workforce (1995-2025). The model predicts the relative growth in the total vascular workforce, accounting the proportion of major vascular surgery performed by surgeons in different age groups.

Specialists Performing Other Vascular Surgery

In addition to major vascular surgery, other operations are performed for vascular disease, including amputation, thrombectomy, hemodialysis access, vascular trauma repair, and varicose vein surgery. These operations are described individually in Chapters Four through Six. In 1996, most of these other vascular operations in Medicare enrollees were performed by general surgeons (51%). Board-certified vascular surgeons and cardiothoracic surgeons performed 24% and 21%, respectively. Orthopedic surgeons, whose involvement is limited to amputations, performed 4%. From 1993 to 1996, the proportion of other vascular surgery performed by board-certified vascular surgeons increased slightly from 21% to 24%.

The proportion of other vascular surgery performed by each specialty varies substantially across hospital referral regions. The percentage performed by vascular surgeons varied from 0% in Boulder, Colorado to 74% in Boise, Idaho. For cardiothoracic surgeons, the proportion ranged from 0.6% in Muskegon, Michigan to 69% in Meridian, Mississippi. The percentage performed by general surgeons varied from 7% in San Angelo, Texas to 87% in Petosky, Michigan, while the percentage performed by orthopedic surgeons varied from 0% in 14 regions to 29% in Abilene, Texas.

Figure 1.11.

Proportion of Other Vascular Surgery Performed by General Surgeons, Vascular Surgeons, Cardiothoracic Surgeons, and Orthopedic Surgeons (1996). Numbers of Medicare enrollees undergoing operations by each type of surgeon are in parentheses.

Map 1.7.

Specialty Type of Surgeon Performing the Plurality of Other Vascular Surgery in Each Hospital Referral Region (1996). General surgeons performed the plurality of other vascular procedures in 230 hospital referral regions.

Specialists Performing Interventional Procedures

Catheter-based interventional procedures have been developed as less-invasive alternatives to surgery for many vascular diseases. They include balloon angioplasty and stent placement, vena cava filters, and thrombolysis, which are described in more detail in Chapters Four through Six. In 1996, most interventional vascular procedures in Medicare enrollees were performed by radiologists (68%). Cardiologists performed 14%, general surgeons 7%, vascular surgeons 6% and cardiothoracic surgeons 4%. From 1993 to 1996, the proportion of interventional procedures performed by board-certified vascular surgeons decreased slightly, from 7.5% to 6.2%.

Although radiologists performed the plurality of interventional procedures in most regions, other specialists performed a large proportion elsewhere. In 1996, cardiologists performed more than 80% of interventional procedures in Houma, Louisiana (91%); Sioux City, Iowa (88%); Victoria, Texas (85%) and Owensboro, Kentucky (81%). General surgeons performed more than half the interventional procedures in Yakima, Washington (73%) and Sun City, Arizona (52%). Cardiothoracic surgeons performed large proportions of these procedures in Albany, Georgia (61%) and Waterloo, Iowa (44%). Vascular surgeons performed more than 50% of interventional procedures in Huntsville, Alabama (67%) and Baton Rouge, Louisiana (58%).

Figure 1.12.

Proportion of Interventional Vascular Procedures Performed by Radiologists, Cardiologists, and Vascular, Cardiothoracic, and General Surgeons. Numbers of Medicare enrollees undergoing procedures by each type of physician are in parentheses.

Map 1.8.

Type of Specialist Performing the Plurality of Interventional Vascular Procedures in Each Hospital Referral Region (1996). Radiologists performed the plurality of procedures in 262 regions.

Chapter One Table

Measures of workforce supply for vascular, cardiothoracic, and general surgeons are expressed as clinical active full time equivalents (FTEs) per 100,000 residents. These rates include only surgeons performing at least two major vascular surgical procedures in Medicare patients in 1996 and meeting Relative Value Unit criteria for being “clinically active.” Workforce supply rates are adjusted for the age, sex, and race of the population in each region. Market share data, also derived from the 1996 Medicare Part B file, are simple proportions.

See the Appendix on Methods for details on the methods used for classifying physician specialty, determining clinical activity, allocating physicians to geographic areas, and adjusting rates.

Chapter One Table

The Vascular Health Care Workforce by Hospital Referral Regions (1996).