Sex Differences in Faculty Rank Among Academic Cardiologists in the United StatesClinical Perspective
Background: Studies demonstrate that women physicians are less likely than men to be full professors. Comprehensive evidence examining whether sex differences in faculty rank exist in academic cardiology, adjusting for experience and research productivity, is lacking. Therefore, we evaluated for sex differences in faculty rank among a comprehensive, contemporary cohort of US cardiologists after adjustment for several factors that impact academic advancement, including measures of clinical experience and research productivity.
Methods: We identified all US cardiologists with medical school faculty appointments in 2014 by using the American Association of Medical Colleges faculty roster and linked this list to a comprehensive physician database from Doximity, a professional networking website for doctors. Data on physician age, sex, years since residency, cardiology subspecialty, publications, National Institutes of Health grants, and registered clinical trials were available for all academic cardiologists. We estimated sex differences in full professorship, adjusting for these factors and medical school–specific fixed effects in a multivariable regression model.
Results: Among 3810 cardiologists with faculty appointments in 2014 (13.3% of all US cardiologists), 630 (16.5%) were women. Women faculty were younger than men (mean age, 48.3 years versus 53.5 years, P<0.001), had fewer total publications (mean number: 16.5 publications versus 25.2 publications; P<0.001), were similarly likely to have National Institutes of Health funding (proportion with at least 1 National Institutes of Health award, 10.8% versus 10.4%; P=0.77), and were less likely to have a registered clinical trial (percentage with at least 1 clinical trial, 8.9% versus 11.1%; P=0.10). Among 3180 men, 973 (30.6%) were full professors in comparison with 100 (15.9%) of 630 women. In adjusted analyses, women were less likely to be full professors than men (adjusted odds ratio, 0.63; 95% confidence interval, 0.43–0.94; P=0.02; adjusted proportions, 22.7% versus 26.7%; absolute difference, –4.0%; 95% confidence interval, –7.5% to –0.7%).
Conclusions: Among cardiology faculty at US medical schools, women were less likely than men to be full professors after accounting for several factors known to influence faculty rank.
Editorial, see p 518
Over the past half-century, medicine has made important progress toward mitigating sex disparities in access to medical training, employment, academic advancement, and promotion. Currently, about half of all US medical school graduates and 38% of all US medical school faculty are women, proportions that have increased dramatically since 1970, when ≈8% of medical school graduates and faculty were female.1–3 Despite this progress, important sex differences persist in medicine, in general, and in academic medicine, in particular. For example, previous work has identified sex differences in salary among, and institutional support for, early career physician-investigators.4–6 Moreover, a recently published analysis of sex differences in academic rank in the United States, which included >90 000 physicians with academic appointments at US medical schools, found significant sex disparities in full and associate professorship even after adjusting for age and several measures of research productivity.1 The proportion of female cardiologists has more than doubled over the past 20 years, from 5% in 1996 to 12.3% in 2013.2,7 Nevertheless, cardiology continues to have the lowest proportion of women of any medical specialty.2 Women are particularly underrepresented in cardiology’s procedural subspecialties, and account for <10% of the physician workforce in both interventional cardiology and electrophysiology.8 Female cardiologists also face several professional and personal challenges that do not impact men, including minimizing radiation exposure before and during pregnancy, and taking maternity leave to have children.7–11 Moreover, 69% of female cardiologists surveyed by the American College of Cardiology in 2006 reported experiencing some form of sex-related discrimination.8 Recent research has also identified sex differences in cardiologists’ salaries that persist after accounting for numerous potential confounders.9 Unconscious sex bias is an important enabler of these persistent sex differences.12,13
These sex disparities in cardiology extend to professional advancement as well. The 2006 American College of Cardiology survey revealed marked sex differences in the perceived speed of professional advancement vis-à-vis professional contemporaries.8 However, to our knowledge, no previous work has specifically examined sex differences in academic rank among US academic cardiologists. Using a unique, comprehensive database of physicians with faculty appointments at US medical schools in 2014, we evaluated sex differences in academic rank among academic cardiologists. Our database included detailed information on several factors known to influence academic rank in medicine, including age, years of experience, subspecialty, research funding, publications, participation in clinical trials, and clinical volume.4,6,14
We obtained and analyzed data from a comprehensive cross-sectional database of US physicians developed by Doximity, a company that provides an online networking service for US physicians. The database contains information about 1 029 088 US physicians as of July 7, 2015.
Doximity uses several mechanisms to identify physicians for inclusion in the database. First, it automatically creates accounts for all physicians included in the National Plan and Provider and Numeration System National Provider Identifier registry. These physicians may then register as users. Second, physicians without active National Provider Identifiers may self-register with Doximity and use its services for free. As of July 7, 2015, 24.0% of all US doctors were registered members (246 786 of 1 029 088).
The company obtains several types of information about each physician, independent of member status, including: age; sex; allopathic (MD) versus osteopathic (DO) training; year of graduation from medical school and residency; medical school name; location of residency training; American Board of Internal Medicine certification, including in internal medicine (IM), IM specialties (eg, cardiology, gastroenterology, etc), and subspecialties (interventional cardiology and electrophysiology, for example); number of publications (including first, last, and total), number of National Institutes of Health (NIH) grants for which the physician was a principle investigator; and number of clinical trials for which the physician was a principle investigator or subinvestigator. These data are obtained from several sources, including: The American Board of Medical Specialties, state licensing boards, PubMed, the NIH RePORT database, ClinicalTrials.gov, and through partnerships with collaborating hospitals and medical schools. A detailed explanation of the database and validation of its accuracy has been published previously.1 We augmented this database by adding each physician’s Medicare revenue in 2013 (which is publicly available from the Centers for Medicare and Medicaid Services) and by identifying physicians with academic appointments at medical schools ranked in the top 20 for research by US News & World Report in 2013.15
Our study population included all cardiologists who were on the list of physician faculty (eg, assistant, associate, and full professors) in the 2014 Association of American Medical Colleges faculty roster. The Association of American Medical Colleges faculty roster is a comprehensive database of US physician faculty, and contains >160 000 active faculty. All accredited US medical schools participate voluntarily in the database and regularly update the faculty roster.16 Thus, the study population represented a comprehensive sample of US cardiologists who were assistant, associate, or full professors at accredited US medical schools in 2014. Each of these cardiologists was matched with their information in the Doximity database. The human subjects review committee at Harvard Medical School approved these data for study and waived participant consent.
The accuracy of the data set was assessed in 2 ways. First, we evaluated the subgroup of cardiologists who were registered members of Doximity (eg, had logged in to activate their accounts). We presumed that the profiles of these registered users might be more complete then those of nonregistered users, and sought to assess whether any differences in profile completeness resulted in differences in outcomes. Second, in a previous analysis, we performed manual audits of the profiles of a random sample of 200 physicians with faculty appointments at US medical schools. We manually confirmed faculty rank (through review of institutional websites); publications in PubMed; clinical trial participation through manual review of ClinicalTrials.gov; and NIH funding through manual review of NIH RePORT database. This validation analysis has been described previously.1
We began by performing unadjusted comparisons of the characteristics of men and women in our cohort by using 2-sided t tests and χ2 tests. Next, we constructed a multivariable logistic regression model to predict the probability of full professorship as a function of physician sex. This multivariable regression analysis adjusted for several other variables that could affect academic advancement among cardiologists and confound sex differences in faculty rank, including age, years since residency completion, subspecialty within cardiology (binary variables for each of the following: interventional cardiology, electrophysiology, noninvasive cardiology), number of publications (first author plus last author, and total), NIH grants (binary variable indicating whether a cardiologist had ever been a principal investigator on an NIH grant), clinical trial participation (binary variable), employment at US medical school ranked in the top 20 US medical schools for research by US News & World Report,15 and Medicare reimbursements in 2013. This model also included medical school–level fixed effects to assist with identifying sex differences in faculty rank among cardiologists within the same school. We used robust standard errors to account for correlations attributable to physician clustering by medical school.
The primary outcome of this analysis was the adjusted odds of full professorship (versus associate and assistant professorship) among women in comparison with men. We calculated adjusted odds ratios to determine associations between each model variable and full professorship. In addition, we calculated the adjusted proportions of full professorship for men and women, and the absolute adjusted difference in proportions, as well, assuming population mean values for all other model variables. We used analogous methods to characterize associations between each model variable and the probability of being a full professor. We considered a 2-tailed P value ≤0.05 to be statistically significant.
In secondary analyses, and using the same variables included in the primary analysis, we estimated new multivariable logistic regression models to evaluate the odds of associate or full professorship (a combined outcome) versus assistant professorship among faculty of all ranks, and full professorship versus associate professorship among faculty with the titles of associate or full professor (eg, excluding assistant professors). We then used these models to calculate adjusted odds ratios of men and women who achieve these outcomes, and to assess odds ratios for secondary outcomes as a function of the other model variables. We also used the models to calculate adjusted differences in proportions for each of these outcomes.
We compared sex differences in full professorship among cardiologists and cohorts of US academic physicians practicing in 7 other IM subspecialties: gastroenterology, infectious diseases, pulmonology, rheumatology, oncology, nephrology, and endocrinology. To do so, we identified all physicians in the Doximity database from each of these specialties who were assistant, associate, or full professors at a US medical school and used our multivariable logistic regression model from the primary analysis to estimate adjusted odds ratios of full professorship between men and women for each IM subspecialty.
We assessed for variation in sex differences in academic rank between medical schools in 2 ways. First, we stratified our cohorts of cardiologists and other IM subspecialists into those affiliated with medical schools ranked in the top 20 for research by US News & World Report in 2013,15 and those affiliated with all other medical schools. We then compared adjusted sex differences in full professorship across IM subspecialties within each stratified level.
Second, we evaluated adjusted sex differences in full professorship for each individual US medical school in the following way. Using the multivariable regression model from our primary analysis, we predicted for each medical school the difference in adjusted proportions of full professorship between men and women if all cardiologists in our cohort were affiliated with that medical school. For each school, we calculated the difference between the observed and predicted sex differences in full professorship (with more negative differences representing greater sex disparities in full professorship).
Our data set was missing information on the year of residency completion for a small number of physicians (287; 6.5% of total), but was otherwise complete. To address this issue, we compared characteristics of physicians with and without missing data and confirmed that nonmissing characteristics were similar between the 2 groups (online-only Data Supplement Table I). We then excluded all physicians with missing data from our analyses.
We performed sensitivity analyses to better understand how NIH funding status and different definitions of cardiology subspecialties influenced our outcomes of interest. First, although we hypothesized that physicians with NIH funding were likely to be on full-time research tracks, it is possible that sex differences in full professorship may differ among those on research versus clinical tracks. To investigate our hypothesis, we added an interaction term between sex and NIH funding status to our model to understand whether sex differences in academic rank were different for research versus nonresearch tracks. Sex was not interacted with any other variables in the model. The outcomes of this analysis were the regression coefficient of the new interaction term and predicted sex differences in full professorship according to NIH funding status by using this newly estimated regression model. In addition, repeat research funding may predict academic advancement, and previous work suggests that women are less likely than men to obtain repeat NIH funding.17,18 We therefore evaluated the adjusted odds of having at least 2 NIH awards (among cardiologists with at least 1 award) as a function of physician sex and the above covariates and also evaluated whether repeat research funding (defined as ≥2 NIH grants among cardiologists with at least 1 grant) was associated with increased adjusted odds of full professorship.
Second, because some practicing interventional cardiologists and electrophysiologists are not American Board of Internal Medicine board certified in these specialties, we assessed whether identifying subspecialists through billing for subspecialty procedures in Medicare claims data affected our results.19,20 To do so, we estimated our multivariable regression analysis 3 times, using 3 different methods for identifying interventional cardiologists and electrophysiologists (see online-only Data Supplement Appendices A and B for description of these methods and list of Current Procedural Terminology codes used for definitions, respectively). All analyses were performed in STATA, version 14.0.
Characteristics of Study Population
Our study included 3810 cardiologists with faculty appointments at US medical schools in 2014 (13.3% of 28 650 cardiologists in the overall database), of whom 16.5% (630/3810) were women (descriptive characteristics for 287 cardiologists excluded from analyses because of missing data are available in online-only Data Supplement Table I). Overall, 28.2% (1074/3810) of all cardiologists were full professors. Female cardiologists were less likely than male cardiologists to be full professors (15.9% [100/630] versus 30.6% [973/3180]; absolute difference, 14.7%, P<0.001; Table 1). Women were more likely than men to be assistant professors (60.2% versus 46.8%; absolute difference, 13.4%; P<0.001) and similarly likely to be associate professors (24.0% versus 22.6%; absolute difference, 1.4%; P=0.47). On the whole, women were younger, less likely to practice an invasive specialty, and had completed residency more recently than their male colleagues. Women were also more likely than men to be faculty at a school ranked highly in research (37.0% versus 31.9%; absolute difference, 5.1%; P=0.02). Female cardiologists had fewer total and first- or last-author publications (mean total, 16.5 versus 25.2; difference –8.7, P<0.001; mean first- or last-author; 9.5 versus 16.4; difference –6.9, P<0.001), and fewer NIH grants (median number of grants among those with at least 1 NIH award; 3 versus 4, P=0.08). Similar proportions of female and male cardiologists had at least 1 NIH grant (10.8% versus 10.4%; difference 0.4%, P=0.77), or helped conduct at least 1 clinical trial (8.9% versus 11.1%, difference –2.2%, P=0.10). On average, women received lower total Medicare payments than men in 2013 ($70 258 versus $95 902; difference –$25 644, P<0.001).
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, female cardiologists were less likely than male cardiologists to be full professors (odds ratio [OR], 0.63; 95% confidence interval [CI], 0.43–0.94; P=0.02; Table 2; absolute difference in proportion, –4.0%; 95% CI, –7.5% to –0.7%; online-only Data Supplement Table II). In addition to male sex, full professorship was positively associated with age, subspecialization in electrophysiology or interventional cardiology, years since residency completion, total publication number, NIH funding, and conducting at least 1 clinical trial, and negatively associated with total Medicare payments.
In additional adjusted analyses, we found no sex differences in the proportions of associate and full professors, in comparison with assistant professors (OR, 1.07; 95% CI, 0.8–1.5; P=0.67; Table 3; adjusted difference, 0.8%; 95% CI, –2.8% to 4.3%; online-only Data Supplement Table III). However, among associate and full professors, women remained significantly less likely than men to be full professors after multivariable adjustment (OR, 0.62; 95% CI, 0.40–0.94, P=0.03; adjusted difference, –7.6%; 95% CI, –13.5% to –0.9%).
Across US medical schools we observed sizeable variation in sex differences in full professorship among cardiologists (Figure). In adjusted analyses, all medical schools in our analysis had negative gaps in full professorship. The adjusted absolute school-specific gaps ranged from ≈–1.4% to –5.2%, and the median gap was –4.8% (interquartile range, –4.2% to –5.1%).
Sex Differences in Full Professorship Across IM Subspecialties and by Medical School Ranking
Cardiology and infectious disease were the only 2 IM specialties in which women had significantly lower odds of full professorship than men (adjusted OR for infectious disease, 0.33; 95% CI, 0.19–0.57; P<0.001) (Table 4). In analyses stratified by medical school ranking within, or outside, the top 20 for research by US News & World Report,15 female cardiologists had nonsignificantly lower odds of full professorship than men in both subgroups (top 20 medical schools: OR, 0.65; 95% CI, 0.34–1.22; P=0.18; non–top 20 medical schools: OR, 0.62; 95% CI, 0.37–1.04; P=0.07). Infectious disease was the only specialty studied that had significant sex differences in full professorship in both medical school strata (top 20 medical schools: OR, 0.10; 95% CI, 0.03–0.33; P<0.001; non–top 20 medical schools: OR, 0.47; 95% CI, 0.24–0.93; P=0.03).
The presence of NIH funding did not modify the relationship between physician sex and full professorship (P=0.99 for interaction term), indicating that similar sex differences in full professorship were present among academic cardiologists with and without NIH funding. Among cardiologists with at least 1 NIH grant, women had nonsignificantly lower adjusted odds of having ≥2 funding awards (OR, 0.55; 95% CI, 0.21–1.5) (Table 5). In comparison with cardiologists with 1 NIH grant, those with ≥2 funding awards had significantly greater adjusted odds of being full professors, although the confidence intervals around the odds ratio estimate were wide and approached 1 (OR, 5.38; 95% CI, 1.03–28.2).
Identifying interventional cardiologists and electrophysiologists using Medicare reimbursements alone, or a combination of American Board of Internal Medicine board certification and Medicare reimbursements, did not affect our findings regarding sex differences in full professorship (online-only Data Supplement Appendices A and B).
We used a comprehensive national database of US physicians to evaluate sex differences in academic rank among US cardiologists with faculty appointments at a US medical school in 2014. After adjusting for physician age, subspecialty training in interventional cardiology or electrophysiology, years since residency training, and several measures of research and clinical productivity, we found that female cardiologists were significantly less likely than their male colleagues to be full professors. Our findings are consistent with recent and older work examining sex differences in academic rank in medicine, including a recent analysis of >90 000 US academic physicians that used the same database that we used for this study, and a 20-year-old, survey-based study of sex disparities in academic advancement among US pediatricians.1,14
To our knowledge, this study is the first such analysis to investigate sex differences in academic rank among US cardiologists. Previous work has identified several drivers of sex differences in academic rank in medicine, including asymmetrical home and childcare responsibilities between men and women21,22; lack of effective mentorship and role models for women23–25; lack of institutional support, in particular, for early-career female researchers5; inconsistent offering of alternative and part-time tenure tracks for nonresearchers26–29; sex bias favoring men in the NIH award application review process, in general, and for R01 awards and repeat funding, in particular17,18; attrition of female academics at higher levels in the academic hierarchy30; overt sex discrimination; and unconscious sex bias.8,12,13,25,30 Female cardiologists report having to contend with many of these challenges. For example, female cardiologists are more likely to delay getting married or starting a family to focus on their training.8,31 Despite the fact that women in cardiology are significantly more likely than men to modify their training or career plans to avoid radiation exposure, 30% of women in cardiology report having performed procedures with radiation risk while pregnant. Female cardiologists are also more likely than men to rely on multiple sources of childcare, and to pay for a fulltime caregiver, in large part, because the majority of male cardiologists with children have spouses who provide full-time childcare.8 Overall, more women than men in cardiology perceive that their personal commitments conflict with their work and hinder their professional advancement.8 In addition, female cardiologists are paid less than men even after accounting for several factors known to impact salary, and the majority of women, 69% in a recent survey, versus 22% of men, report having experienced workplace discrimination during their careers.8,9 Although this same study found that women and men were similarly satisfied with the availability and quality of mentors, several other studies have found that women in medicine, in general, and in cardiology, in particular, struggle more than men to find effective mentorship and role models.7,8,14,32,33
Although the proportion of US female cardiologists practicing in academic settings is increasing,7,8 we are aware of only 2 survey-based studies, both performed by the American College of Cardiology Women in Cardiology Council, that report results specifically about women in academic cardiology. The more recent of these 2 analyses found that women in academic cardiology were significantly more dissatisfied with their careers than men; importantly, this finding did not generalize to analyses of cardiologists in nonacademic practices.8 Academic and nonacademic female cardiologists may have different career goals and priorities and may face different combinations of barriers to professional advancement. Therefore, studies focused on the experiences of women in academic cardiology would be extremely helpful for understanding the particular forces that influence career advancement for these women.
We also found that, although female and male cardiologists were similarly likely to be associate or full professors (a combined outcome), women were less likely than men to hold the title of full professors than associate professor. Because these analyses do not control for cardiologists who exited each of these academic tiers in 2014, no firm conclusions can be drawn from our work about the presence of sex disparities in promotion among academic cardiologists. However, if sex disparities in promotion in academic cardiology do exist, these differences may exist at one or multiple levels in the academic hierarchy. Moreover, because disparities at different academic levels may have different root causes, disparate approaches may be necessary to effectively address them.1
Our retrospective cross-sectional study design limits our ability to identify the causal mechanisms underlying our findings. Nonetheless, we identified multiple independent predictors of cardiologists’ academic rank that have implications for future efforts to identify causal links between physician sex and academic rank, in general, and within cardiology, in particular. For example, physician age and experience (as determined by years since residency) were strongly and independently associated with academic rank, and the female cardiologists in our analysis were younger and had fewer years of experience. It is possible that age and experience afford professional opportunities, including promotion to local and national leadership positions, the receipt of awards, or simply time to cultivate a reputation, which increase the likelihood of promotion, but which we could not measure. Experience may be particularly important for individuals who are promoted on clinical tracks, and the fact that we did not identify an independent association between academic rank and the number of first and last author publications, which are widely viewed to impact academic advancement among researchers, raises the possibility that many of the cardiologists in our study were being promoted on clinical tracks. Furthermore, the fact that women had fewer total publications than men, and that total publications were positively associated with academic rank, raises the possibility that our results could reflect sex differences in access to resources necessary to generate high publication volumes, including mentorship, time, funding (particularly early-career funding), and research networks and teams. Previous work has demonstrated sex differences in physicians’ access to each of these resources.4,7–10,24 In addition, subspecialization in interventional cardiology and electrophysiology, cardiology subspecialties in which women are relatively underrepresented, was also independently and positively associated with academic rank. Although the mechanisms underlying this association are unclear, they could reflect ≥1 of several factors, including population-level demand for invasive services, greater revenue generation by invasive in comparison with noninvasive specialists, and greater likelihood of participation in one of the many clinical trials of invasive cardiovascular disease treatments.
The significant heterogeneity in sex differences in full professorship across IM specialties that we observed are generally consistent with findings from a previous study demonstrating sex differences in academic rank across medical specialties.1 Importantly, this finding suggests that local, specialty-specific elements, including access to mentorship, research time protection, and decisions about whom to recommend for promotion, may contribute as much, if not more, to sex disparities in rank as institutional- and systems-level policies. These findings also highlight that additional efforts to understand and compare promotion practices across IM specialties may help to elucidate mechanisms underlying sex differences within cardiology.
Several factors may contribute to the variation across US medical schools in the adjusted full professorship gap for female cardiologists observed in this study. First, different promotion practices and criteria across medical schools, including variations in the types of tenure tracks offered,27,28 thresholds for promotion,29,34 work-life balance and part-time tenure-track policies,21,35 and the length of probationary periods before achieving a tenure-track position,26 may influence male and female academic cardiologists differently. For example, there exists significant heterogeneity across medical schools in the presence and design of clinician educator tracks (CETs) and in the eligibility of physicians on CETs for tenure.28 CETs, which have proliferated in the past 20 years, were available at ≈75% of US medical schools in 2011.28 Although >75% of CETs contain more women than men, physicians in CETs are often promoted more slowly than those in tenure and research tracks. Although medical schools use objective criteria to assess faculty performance, the promotion process remains heavily influenced by subjective assessments by divisional and departmental leaders. Indeed, at up to one-half of medical schools, department and promotion committee chairs disagree significantly on the relative importance of different CET promotion criteria.29 Second, medical schools, and their cardiology divisions, may vary in terms of their focus on recruiting, supporting, and retaining female cardiologists. Third, cardiology training programs vary widely in their missions and in their capacity to prepare trainees for successful careers in academic cardiology. Importantly, sex differences in full professorship among cardiologists were consistent across medical schools ranked highly and less highly in research, arguing against effect modification attributable to differential prioritization of research success across schools. Nonetheless, we do not know the degree to which these, and other factors, account for our findings. Thus, further research is necessary to understand the origins of variation across medical schools in sex differences in academic rank. This finding also intimates that efforts to rectify national disparities should include interventions at the medical school level. Efforts to widely disseminate information about the experiences of those schools with the smallest sex differences in academic rank might help leaders of schools with larger (eg, more negative) sex-based professorship gaps to learn how to more effectively mitigate them.
One commonly proposed explanation for apparent sex differences in promotion or achievement is that women, but not men, may take several months to years off from work for childbearing. It is certainly plausible that maternity leave could delay the attainment of a given academic rank. However, the American College of Cardiology Women in Cardiology council’s most recent Professional Life Survey found that <25% of female and male cardiologists interrupted training or clinical practice for ≥3 months, only 11% of female and male cardiologists interrupted clinical practice for ≥6 consecutive months, and that female trainees were significantly less likely than male trainees to interrupt training for ≥12 months.8 It therefore seems improbable that our findings could be attributed solely to the fact that women take off more time than men to bear children. Furthermore, more than three-quarters of female cardiologists with children have 1 or 2 children, suggesting that the cumulative amount of maternity leave taken by female cardiologists is similarly unlikely to explain our findings.
Importantly, our results may partially assuage legitimate concerns that the constellation of challenges faced by women in cardiology are dissuading young female trainees from pursuing careers in cardiology, in general, and in academic cardiology, in particular.7,10,31 Indeed, more than half of the female cardiologists in this study were <50 years of age, and 37.2% were <45 years. Although longitudinal data are necessary to determine if and how these demographics are changing over time, this finding is nonetheless encouraging.
Our study has several limitations. First, we lacked information about faculty career track, which could confound our results if women are less likely to be full professors because they disproportionately pursue nonresearch tracks, in which full professorship is less common.28 We addressed this issue, in part, by adjusting for total Medicare reimbursement, which should correlate with total clinical volume, and being on a nonresearch track. In addition, we performed a sensitivity analysis which demonstrated that sex differences in full professorship did not differ significantly between those with NIH funding, who presumably are more likely to be on full-time research tracks, and those without it. Second, we lacked data on whether cardiologists in our cohort worked full time or part time, which could also potentially confound our results if women are more likely to work part time. However, previous work demonstrates that the vast majority of female and male cardiologists, at least 80% of women and 80% to 90% of men work full time.8,9 Thus, any sex differences in full-time employment among academic cardiologists that do exist are likely modest in size, and unlikely to single-handedly explain our findings. Third, our database did not include information about non-NIH grant awards. Many clinician-researchers in cardiology rely on grant support from nongovernmental organizations, including the American Heart Association and private businesses, and early-career investigators may receive institutional support for their work.4,5 It is therefore likely that using NIH awards as the sole measure of external financial support for research underestimates the number of cardiologists with research support. Nonetheless, by also examining publications and clinical trials, 2 of the major products of funded research, we likely capture, and adjust for, much of the individual variation in research productivity and non-NIH research funding. Fourth, because clinical trial registration on ClinicalTrials.gov attributes each clinical trial to a single principal investigator, our approach may therefore underestimate cardiologists’ involvement in clinical trials. Fifth, we did not adjust for administrative and leadership roles, such as division chair or fellowship director, that could impact academic rank. Sixth, because our study was cross sectional, we could not assess for sex differences in promotion. Longitudinal data are needed to evaluate promotion practices. Seventh, our measures of research and clinical productivity do not account for several factors that may impact academic advancement, including teaching awards, presentations, committee service, and peer evaluations. However, these factors may have a greater impact on the promotion of physicians on nonresearch tracks, including CET, which include more women than men. Thus, adjusting for these factors could increase sex disparities in academic rank. Eighth, academic cardiologists likely vary widely in their career priorities and interest in becoming full professors. Our analyses do not control for this heterogeneity of values and priorities. Finally, we cannot rule out residual confounding because of unmeasured variables.
Among >3800 academic cardiologists with faculty appointments at US medical schools in 2014, women were less likely than men to be full professors, even after accounting for age, years since residency, subspecialty practice, Medicare reimbursements, and several measures of research productivity.
Sources of Funding
The authors report funding grant 1DP50D017897-01 Early Independence Award from the Office of the Director, National Institutes of Health (to Dr Jena).
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/lookup/suppl/doi:10.1161/CIRCULATIONAHA.116.023520/-/DC1.
Circulation is available at http://circ.ahajournals.org.
- Received May 14, 2016.
- Accepted November 3, 2016.
- © 2017 American Heart Association, Inc.
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What Is New?
This analysis investigated sex differences in academic rank among 3810 cardiologists affiliated with 109 US medical schools in 2014.
After adjusting for age, clinical experience, cardiology subspecialty, and multiple measures of research and clinical productivity, the authors found that the odds of being a full professor were 37% lower among women than men (adjusted odds ratio, 0.63; 95% confidence interval; 0.43–0.94; P=0.02).
In comparisons of sex differences in full professorship across 8 internal medicine specialties, cardiology and infectious disease were the only 2 subspecialties in which women had significantly lower odds of full professorship than men.
What Are the Clinical Implications?
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.
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.