After adjusting for several variables, researchers found that women cardiologists had a 37 percent lower chance of being a full professor at U.S. medical schools than men.

The researchers adjusted for age, clinical experience and cardiology subspecialty, as well as multiple measures of research and clinical productivity.

Lead researcher Daniel M. Blumenthal, MD, MBA, of Massachusetts General Hospital in Boston, and colleagues published their results online Feb. 2 in Circulation.

Today, approximately half of U.S. medical school graduates and 38 percent of U.S. medical school faculty are women, up from 8 percent for both measures in 1970, according to the researchers. However, they noted that previous research found significant sex disparities in full and associate professorship after adjusting to age and research productivity. In addition, the proportion of female cardiologists has increased from 5 percent in 1996 to 12.3 percent in 2013, although cardiology has the lowest proportion of women of any specialty.

For this study, the researchers evaluated more than one million U.S. physicians who were in a database developed by Doximity, which provides an online networking service for U.S. physicians.

They identified 3,810 cardiologists who had faculty appointments at U.S. medical schools in 2014, of whom 16.5 percent were women and 28.2 percent were full professors. They found that female cardiologists were significantly less likely than men to be full professors, significantly more likely than men to be assistant professors and similarly likely to be associate professors.

Women were younger, less likely to practice an invasive specialty and more likely to be faculty at a school ranked highly in research. In addition, women had fewer publications and fewer National Institutes of Health (NIH) grants. Further, in 2013, women received an average of $70,258 in Medicare payments compared with $95,902 for men.

Women cardiologists were significantly less likely than men to be full professors even after adjusting for age, subspecialty, years since residency, publication number, NIH funding, clinical trial participation, affiliation with a medical school ranked highly in research and 2013 Medicare payments.

The researchers mentioned that cardiology and infectious disease were the only two internal specialties in which women had significantly lower odds of full professorship than men.

They noted that the study had a few limitations, including its retrospective, cross-sectional design, which limited their ability to identify causal mechanisms. They also did not have information on faculty career track or non-NIH grant awards or whether cardiologists worked full time or part time. In addition, they did not account for teaching awards, presentations, committee service, peer evaluations or other measures that could affect academic advancement.

“Significant sex differences in academic rank exist among cardiology faculty at US medical schools, and these sex differences are not explained by a number of factors that influence academic rank, including several measures of research and clinical productivity,” the researchers wrote. “Additional efforts to understand the mechanisms underlying these disparities, and to develop targeted interventions to correct them, are urgently needed. 
In particular, further investigations of the heterogeneity in sex differences in academic rank across internal medicine specialties may help to elucidate factors that propagate these disparities within cardiology.”