Gender Differences in Research Project Grants and R01 Grants at the National Institutes of Health

Objectives The National Institutes of Health (NIH), which is the world's largest funding source for research, offers various types of competitive grants depending on the duration, research type, and budget. The Research Project Grant (RPG) is the oldest mechanism for grant allocation that is used by the NIH. In this study, we explored the gender trends of NIH RPGs and R01 grants over the last two decades. Methods By utilizing the NIH Research Portfolio Online Reporting Tool (RePORT), data for gender were extracted, and the percentage of women as RPGs Investigators, R01-equivalent grant including R01 type 1 and type 2 grant awardees, from 1998 to 2019 were tabulated. The absolute change was calculated. Results From 1998 to 2019, the percentage of female RPG awardees has increased. However, the success rates for female RPG applicants have decreased during the same period. The funding and success rates for new R01 awards have been similar for both men and women, but women have been less successful at the renewal of R01-equivalent awards. Conclusion Gender disparity exists in awardees of higher RPGs, including the R01 award. This highlights the need for further actions to ensure gender parity in grant allocations at the NIH.


Introduction
Women have narrowed the gender gap with men among biomedical science degree holders, but they are lagging behind in academic ranks and leadership positions [1][2][3]. Women were 49% of all PhD degree awardees in biological sciences in 2005, and it increased to 52% in 2010 [4]. However, female assistant professors with a biology PhD constituted only 44% of the faculty in 2015 [5]. Similar discrepancies between PhD holders and faculty representation also persist in academic medicine [2,6,7], professional medical societies [8][9][10], and editorial boards of medical journals [11,12]. The National Institutes of Health (NIH), which is the world's leading source of public funding for biomedical research, receives disproportionally a lower number of newer grant applications from women [13]. Furthermore, less than one-third of NIH research grantees are comprised of women, even though their success rates are similar for obtaining first grants compared to men [14].
The NIH achieves its goal of expanding biomedical research by supporting research in different domains through the administration of various grant types [15]. These grants are pivotal for scientists to carry out research activities, run their laboratories, and apply for promotions and tenure [16]. The NIH also plays a pivotal role in the contribution to the nation's economy by creating jobs and increasing the demand for local services as well as serve as a foundation for the United States (U.S.) biomedical industry. It is estimated that approximately every US dollar of NIH funding generates ≈$2.21 in local economic growth [17].
Various funding opportunities are available through the NIH. The Research Project Grant (RPG) is the original and oldest mechanism of grant used by the NIH. The NIH grants are specified by an activity code representing the type of research being funded [13]. The R01 award is the "gold standard" of research awards and provides funding and support for health-related research and development based on the mission of the NIH [17]. The NIH has two types of applications for R01 grants including R01 New (Type 1) and R01 Renewal (Type 2) [18].
It is critical to explore the trends of gender disparity in NIH funding to address academic and scholarly diversity. In our study, we explored the trends of the NIH R01 grant and characterized the potential explanations for any existing gender differences. We also analyzed NIH funding trajectories over time, comparing gender differences for the early stage of women's careers and whether they continue to stay funded at the same rates as men. We explored the differences in funding trajectories for men and women from 1998 to 2019, using NIH grant records for investigators who received a major NIH RPG for the last two decades.

Materials And Methods
Our methodology has been validated in recent publications [19]. This retrospective study did not require Institutional Ethics Board approval as the data were exported from publicly available data at the NIH Research Portfolio Online Reporting Tools (RePORT) -NIH Data Book. We utilized the NIH grant and funding reports for the consecutive fiscal years 1998 to 2019.

Variables
The percentage of women receiving RPGs, and the differences in the annual applications, awards, and success rates for the RPGs by gender were extracted and tabulated. Similarly, the percentage of women receiving the R01-equivalent awards and the success rates by type of application (Type 1/New or Type 2/Renewal) were compared over the study period to examine the temporal trends. The average funding of R01-equivalent grants in current and constant dollars was also compared between genders.

Data analysis
We analyzed the categorical data by gender and its temporal trend by year and across RPGs and R01 awards. The award success rate was compared for RPGs and R01-equivalent grants, and absolute change (%) was calculated from the years 1998 to 2019. Tables were created to highlight and compare the gender percentages for each category and year.

Results
The contribution and involvement of women in research development from the year 1998 to 2019 were tabulated ( Table 1). There has been a substantial increase in the overall percentage of women receiving RPGs at the NIH over the last 21 years and it is continually increasing. There was an absolute increase of 11% from 1998 to 2019 (Table 1).   In the comparison of the competing applications and award success rate, there was a smaller decrease in the observed success rates for female RPG applicants at -9% compared to -12% in their male counterparts ( Table  2).   Women had a significant increase from 5,203 to 9,263 between 1998 and 2019 as the recipients of R01 grants ( Table 3). The percentage of total R01 grants received by women increased by 9% in the same period.

Discussion
We studied gender disparity in NIH grant awards and funding from 1998 to 2019. There was an overall increase in the percentage of female awardees for all categories of RPGs from 22% to 33% between the years 1998 and 2019, with an absolute increase of 11%. The number of female RPG applicants increased from 5,763 to 17,857 from 1998 to 2019. However, the success rates for female RPG applicants decreased from 30% to 21%, with an absolute decrease of 9% for the same period. Women have made progress as recipients of various RPGs; however, the percentage of female awardees is not comparable to their representation in the population. The percentage of R01-equivalent grants awarded to women increased by approximately 22% to 31% between 1998 and 2019, with an absolute increase of 9% [18]. The increase in average funding in current and constant dollars for the R01-equivalent grant awarded to women also increased slightly more than their male counterparts. A study revealed that women with an MD degree were awarded larger NIH R01 grants in obstetrics and gynecology than males with an MD degree between 2008 and 2017 [20].
Our study showed a substantial decline between 1998 and 2007 for women receiving R01 award(s). The percentage of women submitting R01-new and R01-equivalent grants did not change through 2001-2003, whereas the percentage of women submitting R01 grant renewal decreased [21]. For the years 2003 to 2007, there was a significant decline in the percentage of women investigators receiving R01 grants (new and renewal) [18,21]. Analysis of the R01 program data showed that funding and success rates for new R01 awards over the past decade have been almost identical between both the genders, but women were less successful at the renewal of R01-equivalent awards [22]. Higher application and success rates have been observed for men having previous experience as NIH grantees than women at similar career points [1]. Although women secured higher numbers of R01 awards than men, men had a greater number of R01 awards than women at all times in their careers [22].
The previous studies exploring the effects of gender on NIH funding suggested contrasting results. A retrospective cohort study (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007) showed that women were less likely than men to receive an R01 grant [23]. Another study analyzing the NIH data regarding contending research and training grants suggested that women were equally or more productive than men in the R01 program, both as first-time applicants and as experienced applicants submitting new applications [18]. However, experienced male researchers were more successful than female researchers for R01 Type 2 (renewal) grant submissions [22]. After controlling for all covariates, male PhDs were significantly more likely than female PhDs to have received at least one R01 award [24]. These findings were also consistent with another study exploring the NIH grant funding in radiology. This study observed a significant gender disparity in mean NIH grants awarded to radiology investigators for 2016-2019 inclusive ($619,807.00 for male PhD investigators compared to $158,486.00 for female PhD investigators) [25].
Analysis of a report (2010-2014) regarding NIH peer reviewers' critique on R01 grant applications showed that gender bias existed in the peer-review process of R01 grants, particularly for R01 type 2 grants (R01renewal grants) [26][27]. Although the percentage of women who received the R01 awards has been on the rise for the last 20 years, the probable attrition in the promotion of women to senior positions can discourage women from entering and staying in academia [28]. Research has been a driving force in the advancement of medicine, and more than half of the world's funding comes from the U.S. [1]. In 2014, the R01 grant accounted for 49% of all NIH extramural funding [2]. The R01 grant is also seen as a turning point in the early career of an academician that can be utilized to promote further granting opportunities [29].
Our study revealed existing gender differences in grant awards, which, in turn, warrants further exploration and intervention. Several factors including a career change and differing grant application strategies may be involved in a high female dropoff rate at first renewal in NIH funding. Further work needs to be conducted to address the explanation why women in academic positions might not be applying or reapplying for RPGs at the same rates as men and how this pattern could be changed [1]. Furthermore, an investigation into why women receive less favorable reviews than men for renewal applications is underway [30]. Over the decade studied, a gender disparity exists in the number of total grants and award dollars that are received by primary investigators for NIH R01 grants. However, a trend has been observed for the increased funding for those women who receive an NIH R01 grant. To combat these gender disparities, further research needs to be conducted to determine the cause and implement remedial actions [29].
There are limitations to our study. In the context of gender disparity, some researchers may self-identify in a non-binary fashion. Furthermore, the data on NIH database are only comprised of information related to those who receive funding. There are no data available on the total number of applications, including male and female applicants. Therefore, the true determination of the relative success rate of male and female researchers and differences in award amounts is not possible. Also, each application for NIH funding includes various personal information such as the name, degree, position, and academic title of the researcher, among others. It is, therefore, plausible that funding decisions are made with the knowledge of an applicant's gender, although the extent to which this knowledge may affect funding decisions, whether explicitly or through implicit bias, is impossible to quantify objectively.

Conclusions
Women have made progress as recipients of various RPGs. However, the percentage of female awardees is not comparable to the higher numbers of female doctoral candidates in the U.S. Despite an overall increase in the percentage of female researchers successfully receiving NIH grants and awards, the gender disparity exists. As apparent from the increasing enrollment of women in medical schools as well as doctoral candidates, and considering the lengthy training periods, it will be a few years before we can see meaningful changes in bridging gender disparity. Therefore, further studies to examine the longitudinal trends and lag times of women dissipating the gender differences are needed. At the same time, the continued support and retention of female researchers are pivotal to further improve the future representation of women in research, and specifically at the NIH.

Additional Information Disclosures
Human subjects: All authors have confirmed that this study did not involve human participants or tissue.
Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue.

Conflicts of interest:
In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.