October 23, 2009

Ebb, flow of physician workforce studied

Ebb, flow of physician workforce studied



The study was led by health care economists Douglas Staiger, Ph.D., of Dartmouth College, David Auerbach, Ph.D., of the Congressional Budget Office, and Peter Buerhaus, Ph.D., R.N., of Vanderbilt's Center for Interdisciplinary Health Workforce Studies and Vanderbilt University School of Nursing.

Recent projections indicate that the supply of physicians may soon decrease below requirements. Some analysts project a physician shortfall of as high as 200,000 by 2020.

Although debate over potential shortages has focused largely on the number and type of physicians needed in the future, the study shows that concerns have also been raised about data used in physician supply estimates and projections.

The researchers compared data from the American Medical Association Physician Masterfile (Masterfile), a data source frequently used by physician workforce analysts, with data from U.S. Census Bureau Current Population Survey (CPS), used extensively by the U.S. Department of Labor to estimate current trends in employment.

The Masterfile data are believed to overestimate the number of active physicians at older ages, attributed to delays in updating the Masterfile data when a physician retires or experiences a change in location, specialty, or immigration, according to the article.

The researchers used data from between 1979 and 2008, and projected physician supply through 2040 using both data sources.

They found that in an average year:

• CPS estimated 67,000 (10 percent) fewer active physicians than did the Masterfile during the sample period.

• Estimates from the Masterfile and CPS data were similar for physicians between the ages of 35 and 54, but differed markedly at both younger and older ages.

• Older physicians accounted almost entirely for the lower estimates of active physicians in the CPS.

• During the sample period, on average, the CPS estimated 22,000 (20 percent) fewer active physicians per year ages 55 to 64 than did the Masterfile, and estimated 35,000 (51 percent) fewer active physicians per year 65 or older than the Masterfile.

• The CPS estimated more young physicians (ages 25 to 34 years) than did the Masterfile, with the difference increasing to an average of 17,000 (12 percent) during the final 15 years.

Regarding projections for the future physician workforce supply, both the CPS and the Masterfile data indicate that the number of active physicians will increase by approximately 20 percent between 2005 and 2020.

However, projections for 2020 using CPS data estimate nearly 100,000 (9 percent) fewer active physicians than projections using the Masterfile data (957,000 vs. 1,050,000), and estimate that a smaller proportion of active physicians will be 65 years or older.

“I was particularly interested in the workforce contributions of female physicians,” said Buerhaus.

Using CPS data and compared with the peak work years of 45 to 54 years, female physicians are 59 percent as active at 25 to 34 years and 98 percent as active at 55 to 64 years.

In contrast, relative to their own peak activity rates, also at ages 45 to 54 years, male physicians are 68 percent as active at 25 to 34 years, but only 83 percent as active at 55 to 64 years, according to the study.

“A lot of women physicians may feel as though they are just reaching their stride in middle age when they are more able to focus on their careers than when they had young children at home,” said Bonnie Miller, M.D., senior associate dean for Health Sciences Education at Vanderbilt University School of Medicine.

“Or, this might reflect pure economics since women still earn lower salaries than men and, especially in the older cohort, were more likely to enter lower-paying specialties, like pediatrics. They simply may not have the means to retire early.”