ÌÇÐÄvlog

Federal funding is associated with the quality of science and researchers’ professional advancement.¹ Female junior faculty received less university start-up support than males in one study,² a factor associated with early-career attrition rates.³ We investigated another potential association: the size of National Institutes of Health (NIH) grant awards to first-time awardees.

Using the public NIH Principal Investigators (PI) database, we analyzed grant amounts to first-time female and male grant awardees from 2006 to 2017. A PI’s sex was determined algorithmically from first names. First-time PIs had no prior NIH awards as far back as 1985.

To examine factors related to funding, we first compared the median number of articles published per year, the median number of citations per article, and the number of areas of research expertise in published articles for first-time female and male PIs prior to their first NIH grant, using Microsoft Academic Graph (MAG). Areas of research expertise were estimated from the articles’ research topic as reported in MAG. Only articles with the PI as the last author were counted.⁴

To further control for confounding, we examined awardees of the top 10 most highly funded grants awarded to individual PIs only, which represents $14 billion in funding or 58% of all NIH funds awarded to 19 559 first-time PIs. Also, we investigated awardees at the same 14 Big Ten and 8 Ivy League universities ($1.8 billion in funding or 7.5% of NIH funds awarded to 8039 first-time PIs), as well as the top 50 NIH most highly funded institutions ($9 billion in funding or 38% of funding awarded to 20 335 first-time PIs). The 2-sided Mann-Whitney test of medians (threshold P < .05) and Python software (version 2.7.12) were used in the analyses.

From 2006 to 2017, 53 903 NIH grants were awarded to first-time PIs across all 225 NIH grant types and 2766 institutions (Table 1). Of first-time PIs, 43.6% were female, similar to the female enrollment level of 38% in US MD-PhD programs during the same period.⁵

Baseline performance measures were available for 73.4% of first-time PIs. No statistically significant differences by sex were found for baseline performance measures. The median number of articles published for men and women per year was 2.0 (P = .64), the median number of citations per article was 15 (P = .99), and the median number of research areas was 2.0 (P = .90).

For first-time PIs across all grant types and institutions, women received a median of $126 615 vs $165 721 for men (median difference, −$39 106 [95% CI, −$46 099 to −$35 675]; P &±ô³Ù; .001). For the 10 highest-funded grant types across all institutions, first-time female PIs received a median award amount of $305 823 vs $316 350 for male PIs (median difference, −$10 527 [95% CI, −$17 240 to −$3082]; P = .002), with the largest differences in N01 and U01 grants. However, women receiving R01 grants received $15 913 more than men (P &±ô³Ù; .001).

Female PIs at the Big Ten universities received a median of $66 365 vs $148 076 for male PIs (median difference, −$81 711 [95% CI, −$92 734 to −$67 450]; P < .001) (Table 2). Similarly, women at Ivy League universities received statistically significantly smaller grant amounts ($52 190 for women vs $71 703 for men; median difference, −$19 513 [95% CI, −$31 310 to −$6976]; P &±ô³Ù; .001). At the top 50 NIH-funded institutions, first-time female awardees received significantly smaller grant amounts ($93 916 for women vs $134 919 for men; median difference, −$41 003 [95% CI, −$47 052 to −$31 316]; P &±ô³Ù; .001).

This study found sex differences in the size of NIH funds awarded to comparable first-time female and male PIs, even at top research institutions. Funding disparities favoring men occurred among certain grant types, although for R01 grants, the most frequent award for first-time awardees, women received larger grants, as previously observed.⁶ Although the analyses controlled for key factors, limitations include possible unmeasured confounding and no data on grant applications that were turned down. Further study of the institutions where inequalities were lowest may provide insight into the reasons for sex imbalances in grant amounts awarded during formative career stages.

Accepted for Publication: December 21, 2018.

Corresponding Author: Teresa K. Woodruff, PhD, Women’s Health Research Institute and Feinberg School of Medicine, Northwestern University, 303 E Superior St, Ste 10-121, Chicago, IL 60611 (tkw@northwestern.edu).

Author Contributions: Dr Uzzi had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Oliveira, Woodruff, Uzzi.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: All authors.

Critical revision of the manuscript for important intellectual content: Oliveira, Woodruff, Uzzi.

Statistical analysis: All authors.

Obtained funding: Woodruff, Uzzi.

Administrative, technical, or material support: Oliveira, Woodruff, Uzzi.

Supervision: Uzzi.

Conflict of Interest Disclosures: None reported.

Funding/Support: This study is based on work supported by grant R01GM112938 from the National Institutes of Health, grant 1747631 from the National Science Foundation, and funding from the Northwestern Institution on Complex Systems and the Kellogg School of Management.

Role of the Funder/Sponsor: The funders played no role in the design or conduct of the study; collection, management, analysis, or interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication.