Although the number of women entering the physician workforce has increased over the past two decades, their earnings still lag behind those of their male colleagues. In a research letter published online in JAMA Internal Medicine, researchers reported that according to the latest salary data, the earnings gap between male and female physicians was $56,019.

The researchers, led by Seth A. Seabury, PhD, of the University of Southern California in Los Angeles, used national data from the March Current Population Survey (CPS) from 1987 to 2010 and estimated trends in the earnings difference among physicians, other health professionals and workers overall.

They analyzed information from three time periods—1987 to 1990, 1996 to 2000 and 2006 to 2010. The trends were evaluated across occupations with adjustments made for age, sex, race, hours worked and state. Their research included data from more than 1,300,000 individuals.

Female physicians increased in number from 10.3 percent in 1987 to 1990 to 28.4 percent in 2006 to 2010, but their earnings did not—the income gap was $34,620 in 1996 to 2000 and $56,019 in 2006 to 2010.

Men dominated the other health care occupations except for nurses and physician assistants. The income gap was smaller for nurses and pharmacists and decreased over time. In non-medical professions, the income differences diminished considerably.

Both adjusted and unadjusted trends are important to understand, the authors argued, because they may reflect an underlying inequality among physicians.

“For example, are unadjusted earnings differences between male and female physicians due to a preference of female physicians for lower-paying specialties (eg, pediatrics or primary care) or do female physicians have less opportunity to enter higher paying specialties despite having similar preferences as male physicians?" asked the authors. "The etiology of the persistent gender gap in physician earnings is unknown and merits further consideration.”