Gender disparities among medical students choosing to pursue careers in medical research: A cross-sectional cohort analysis

Background: Though the proportion of women in medical schools has increased, gender disparities among those who pursue research careers still exists. In this study, we seek to better understand the main factors contributing to the existing gender disparities among medical students choosing to pursue careers in medical research. Methods: A cross-sectional cohort analysis was conducted using a 70-item survey that was sent to 16,418 medical students at 32 academic medical centers and was IRB approved at the University of Illinois at Chicago and the University of Pennsylvania. Data was collected from September 2012 to December 2014. Survey results were analyzed using chi-square tests to determine gender differences in demographic characteristics (training stage, race/ethnicity, marital status, parental status, nancial support, and parental career background), career sector choice, career content choice, specialty choice, foreseeable career obstacles, and perceptions about medical research careers. Results: There were 4433 respondents (27% response rate). Female respondents were more likely to be enrolled in MD-only programs, while male respondents were more likely to be enrolled in MD/PhD programs. More male trainees selected academia as their rst-choice career sector, while more female respondents selected hospitalist as their rst-choice career sector. More female respondents identied patient care and opportunities for community service as their top career selection factors, while more male respondents identied research and teaching as their top career selection factors. Conclusions: There are many factors from a medical student’s perspective that contribute to the existing gender disparities in pursuing a career in medical research, including student loan burden, future compensation, work/life balance, and family/caretaker obligations. While much progress has been made in attracting nearly equal numbers of men and women to the eld of medicine, active efforts to bridge the gap between men and women in medical research careers are needed.


Introduction
Physician-scientists have long been considered an endangered species and the female physicianscientist an even more rare entity (1). Despite efforts to attract physicians to medical research, interest has continued to dwindle, especially among female trainees. Furthermore, women also continue to be underrepresented in leadership and administrative roles in academic medicine (2). While the causes of these phenomena have long been debated and are certainly multi-factorial, no solutions have been realized.
At beginning of the 20th century, Samuel Meltzer described his vision of the physician-scientist at the rst meeting of what is now the American Society for Clinical Investigation. He stressed the importance of developing investigators capable of conducting research across disciplines and producing work that satis es their respective criteria. According to Meltzer, "Clinical science will not thrive through chance investigations by friendly neighbors from the adjoining practical and scienti c domains" (3). Today, physician-scientists undergo in-depth training in both science and medicine which uniquely equips them to tackle challenges at the forefront of translational research. While MD-PhD students make-up just 2.5% of medical school graduates each year, they will go on to win nearly one-third of all NIH research grants awarded to physicians (4). They represent a highly motivated and talented pool of trainees that are vital to the future of medical research. Yet for the past three decades, many have expressed concern that physician-scientists are an "endangered species." For reasons that are not well understood, the interest in medical research has been dwindling (5)(6)(7). To ensure a steady ow of diverse talent, we must assess the attitudes that guide the professional decisions of tomorrow's physicians today.
Since the 1970s, the overall proportion of physician-scientists in biomedical research has contracted, yet the absolute number in the workforce has remained stable. This stability has masked alarming trends that could ultimately deplete the workforce. According to a 2014 report from the NIH, only 1.5% of MDs consider research their primary focus with even fewer physicians receiving funding as principal investigators on NIH grants (0.9%), split evenly between MDs and MD-PhDs (8). Whereas the number of nonphysician (PhD) NIH-funded investigators has increased by 50% over the last 20 years, the number of NIH-funded physician-scientists has essentially remained constant. Although public policies have encouraged an increase in the number of medical schools and medical students in the US, and medical school admission policies have placed value on undergraduate research, the percentage of physicians focused on research has fallen substantially.
The stagnating physician-scientist workforce has also failed to keep pace with the increase in racial and gender diversity of its MD counterpart. The ever-growing body of evidence continues to support the importance of achieving greater diversity in the biomedical workforce (9). Much progress has been made in attracting nearly equal numbers of both men and women to careers in medical science as both physicians and physician scientists, yet the pipeline remains leaky with striking losses of female talent at higher levels of academic medicine (10,11). Historically, the female physician was a rarity. In the 1970s, the proportion of women graduating from US medical schools nearly tripled by the end of that decade (12). Today, women comprise 46% of residents, yet the proportion of women at the rank of full professor (12%) remains far below that of men (13).
Unfortunately, the increase in the proportion of women in medical schools has not been met with a comparable increase in women pursuing research careers. Women are much less likely than their male counterparts to express interest in a career of medical research altogether, at either matriculation or graduation. Furthermore, women who initially express interest in pursuing research as part of their careers are more likely to lose their research career aspirations throughout medical school (14). The reasons for these disparities are certainly multifactorial and likely include factors such as lack of adequate role models, gender discrimination/bias, and work-life balance, but there remain many inconsistencies in the contribution of these factors to this alarming trend (15). In this study, we aim to further understand the drivers behind this disparity in interest in medical research careers through a nationwide survey conducted at 32 academic medical centers in the United States.

Data collection
The study was reviewed and exempted by the Institutional Review Board at the University of Illinois at Chicago and the University of Pennsylvania. A cross-sectional cohort analysis was conducted using a 70item survey that was designed with feedback from a survey design team at the University of Illinois at Chicago (16, 17). Data were collected using an online survey tool (SurveyMonkey, www.surveymonkey.com ). The survey was sent in September 2012 via e-mail to 16,418 MD and MD/PhD students at 32 academic medical centers through student listservs and the institutional representatives of the American Physician Scientists Association (APSA). Participants had the option of entering their institutional email address for a chance to receive a $50 Amazon gift certi cate. Data collection ended in December 2014. E-mail addresses were kept separate from survey responses to maintain the anonymity of responses.
MD/PhD students were identi ed through how they paid for medical school as being sponsored by an MD/PhD program. MD candidates interested in research-intensive careers (MD-RI) were identi ed by their career intentions of wanting a research to clinical duty ratio of 50% or greater, which re ects the NIH guidelines for surgeon scientists.

Statistical analysis
Survey results were analyzed to determine signi cant gender differences in demographic characteristics (training stage, race/ethnicity, marital status, parental status, nancial support, and parental career background), career sector choice, career content choice, specialty choice, foreseeable career obstacles, and perceptions about medical research careers. Chi-squared tests were used to measure the signi cance of associations between categorical variables. Where data did not meet minimum expected cell counts, Fisher's exact test was performed. All tests were performed using SPSS. All tests of signi cance were 2sided and p < 0.01 was considered signi cant. Acute care specialties included pulmonary critical care, anesthesiology, and emergency medicine.

Demographics
There were 4433 respondents (27% response rate). Demographic characteristics (gender, training stage, race/ethnicity, marital status, parental status, nancial support, and parental career background) of respondents are summarized in Table 1.     c Top choice specialty of interest for participants separated by gender. The following specialties were included in the category "Medicine" for better visualization: allergy and immunology, dermatology, family medicine, internal medicine, internal medicine subspecialties, medical genetics, pathology, pediatrics, physical medicine and rehabilitation, preventive medicine, and psychiatry. The following specialties were included in the category "Surgery" for better visualization: surgical subspecialties, obstetrics and gynecology, ophthalmology, otolaryngology, and urology. The following specialties were included in the category "Radiology" for better visualization: nuclear medicine and radiation oncology. The category "Other/NA" was excluded for better visualization.

Perceived important factors in job recruitment
During recruitment of applicants for jobs and/or positions in science and medicine, female and male respondents similarly perceived talent and accomplishments to be "a great deal of importance" (669, 30.7% versus 519, 31.1%) and "a lot of importance" (1070, 49.1% versus 789, 47.2%) (p = 0.30).

Discussion
There continues to be signi cant gender disparities in many factors surrounding medical student interest in research. These results, collected from medical students across several large academic centers, are consistent with prior ndings in the literature related to gender disparities, and they expand on these ndings by detailing several contributing factors for these differences from a medical student's perspective.
Notably, more males were found through our study to pay for medical school through MD/PhD or DO/PhD program funding, scholarships, grants, and national service, thus leading to a signi cantly reduced nancial/loan burden. The study also found that more females identify loan repayment as a top foreseeable obstacle to pursuing medical research compared to males, consistent with current literature which states that female matriculation rates consistently remain below 50% among all MSTP programs (18). Our data further supports this as male respondents were more likely to be enrolled in MD/PhD programs (25.6% vs 16.9%) compared to female respondents.
Furthermore, fewer females identi ed under-compensation as a top foreseeable obstacle to pursuing a career in research. However, females in the medical profession continue to experience the wage gap which persists through all sectors of society (19). There may be many reasons for this discordance, one of which may be societal pressure on women to ful ll the heteronormative gender role as the primary caregiver for the family and children, though the contribution of this factor is still debated (15). Our study further supports this possibility in the nding that a greater percentage of females chose "balancing family and work responsibilities" as the number one factor for both their specialty choice and foreseeable obstacle in pursuing research. A related factor that may contribute is that women are much less likely to promote themselves or negotiate on their behalf in the workplace (20).
Along with work/life balance, female respondents reported signi cant expected non-work-related factors that would impede their ability to pursue a career in research, all of which were reported at higher rates compared to their male colleagues. These factors include raising children, caring for elderly parents, being a caretaker for others, and nancially supporting others. These responsibilities have been magni ed more than ever by the COVID-19 pandemic, leading to more women having to take time off from clinical duties due to increasing demands outside of work (21). Additionally, a larger portion of male respondents reported having children (7.8% vs 4.3%) while completing their studies. This could potentially be explained by the fact that male students had spouses who shouldered the childcare responsibilities while female students did not.
Finally, a notable nding in our study was that while more females saw research intensive careers in surgical and acute care specialties as feasible, fewer females indicated an intent to pursue basic and translational research. This discrepancy is consistent with the continued minority of women entering surgical and acute care specialties, despite recent parity in absolute numbers of students entering the resident workforce (22). Even with apparent knowledge of the opportunity to conduct research in these specialty areas, there are still factors that dissuade entry into these procedural career options. Of course, this decision is multifactorial, but a lesser desirability in pursuing a research career may play a role.
Although this is a large cross-sectional cohort analysis, with a total of 4,433 respondents from a nationally representative cohort of medical schools, there are a few limitations to this study. First, this was only a snapshot in time of what trainees are interested in and intending to pursue as a career, and thus a follow-up study to determine their ultimate career choice will be important. Second, given the nature of self-reported surveys, there was the inherent limitation in being unable to assess more deeply the motivations behind the answers of the respondents.
There are a multitude of factors that contribute to the continued disparities in interest in pursuing a career in medical research among medical students. These factors are still largely unknown, but by the merits of this study, may include nancial burden from student loans, under-compensation, work/life balance, and expected familial/caretaker obligations among other factors. Without concerted efforts to bridge this gap between men and women, these disparities will persist. With the current focus on inclusion and diversi cation in academic medicine, these efforts must target minority populations to ensure these changes come to fruition in the coming years (23,24).

APSA -American Physician Scientists Association
Declarations Ethics approval and consent to participate: The study was reviewed and exempted by the Institutional Review Board.
Consent for publication: Not applicable.