Originally published in MedPage Today
by Charles Bankhead, MedPage Today Staff Writer
The physician workforce in the U.S. is growing smaller and younger, according to data from the Census Bureau, but conflicting estimates make it difficult to determine just how many doctors are out there — and how many the nation will need.
The census survey showed 67,000 fewer physicians than estimates based on the AMA Physician Masterfile. Whatever the actual number, the reduction in the workforce has been almost entirely the result of fewer active physicians ages 55 and older.
At the other end of the career time line, the census data suggested that the number of physicians ages 25 to 34 will continue to increase over the next 15 years.
“Projections based on both the CPS [Current Population Survey] and the Masterfile data indicate that the number of active physicians will increase by approximately 20% between 2005 and 2020,” Douglas O. Staiger, PhD, of Dartmouth College in Hanover, N.H., and colleagues reported in the Oct. 21 issue of JAMA.
“However, projections for 2020 using [census] data estimate nearly 100,000 fewer active physicians than projections using the Masterfile data.”
Compared with the AMA data, the census survey indicated that a smaller proportion of physicians will be 65 and older by 2020 (9% of total doctors versus 18%), they added.
Recent studies have indicated that the physician workforce may shrink to levels that do not meet national requirements by 2020. Some sources have estimated a shortfall of as many as 200,000 physicians, the authors said.
Studies of the physician workforce have often relied on the AMA Masterfile, which may overestimate the number of active older physicians because of delays in updating the database, they continued. As a result, recent workforce projections have reflected various adjustments to account for those delays.
To examine the extent to which the physician workforce might be overestimated, the authors conducted a parallel retrospective cohort study comparing the AMA Physician Masterfile and the Census Bureau Current Population Survey.
The Department of Labor has used the census data to examine employment trends, including trends for registered nurses. Both data sources were used to project the U.S. physician supply through 2040.
The authors examined employment trends among active physicians from 1979 to 2008 and used recent trends to project the future physician workforce by 10-year age increments. The authors defined active practice as at least 20 hours per week.
In comparing the two data sources, the authors found that census projections for the physician workforce in any given year were 10% (67,000) lower than those of the AMA (95% CI 57,000 to 78,000, P<0.001). The differences remained stable over the entire period reviewed.
Much of the difference between the two data sources came from projections for different age groups. The census data resulted in estimates that included about 22,000 (20%) fewer physicians ages 55 to 64 (95% CI 17,000 to 22,000, P<0.001) and about 35,000 (51%) fewer active physicians ages 65 and older (95% CI 29,000 to 40,000, P<0.001).
The census data resulted in 9,000 (6%) more active physicians ages 25 to 34 than the AMA Masterfile (95% CI 4,000 to 15,000, P<0.001).
Age effects on workforce projections differed significantly between the two data sources, as the census data implied a more rapid decline in the number of active physicians in older age groups (P<0.001).
For example, AMA data indicated that 86% as many physicians ages 65 to 74 will remain active relative to physicians ages 45 to 54. Census data suggested only 44% of older physicians will remain active compared with those in the 45-to-54 age category.
The census data indicated that 957,000 physicians will be active in 2020 compared with 1,050,000 projected by the AMA data. The increasing proportion of female physicians did not significantly affect workforce projections of the two data sources because more female physicians remained active after age 55.
The ongoing debate over healthcare reform has major implications for physician supply, Thomas C. Ricketts, PhD, of the University of North Carolina at Chapel Hill, wrote in an editorial.
“If access is expanded through subsidy to health insurance, the demand for physician services will increase potentially beyond what is available,” said Ricketts. “If physician supply is in excess of what the market will bear, the prices of those services may increase to unsustainable levels.”
Determining the “right number” of physicians is difficult, particularly if they can’t be counted accurately, Ricketts continued. However, he declared, “enough is known about the distorting effects of an oversupply as well as an undersupply of physicians to provoke a search for accuracy.”
The physician workforce is a critical factor that must be considered in the debate over healthcare reform. An accurate count of active physicians will be critical to achieving and sustaining effective healthcare reform, Ricketts concluded.