Recruitment of women in neurosurgery: a 7-year quantitative analysis

James FeghaliDepartment of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland; and

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Albert AntarDepartment of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland; and

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Elizabeth E. WicksDepartment of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland; and

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Shahab Aldin SattariDepartment of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland; and

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Sean LiPratt School of Engineering, Duke University, Durham, North Carolina

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Timothy F. WithamDepartment of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland; and

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Henry BremDepartment of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland; and

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Judy HuangDepartment of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland; and

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OBJECTIVE

The authors aimed to characterize which US medical schools have the most female neurosurgery residents and to identify potential associations between medical school characteristics and successful recruitment of women pursuing a neurosurgery career.

METHODS

The authors evaluated a total of 1572 residents in US neurosurgery programs accredited by the Accreditation Council for Graduate Medical Education as of February 2021, representing match cohorts from 2014 to 2020. The authors extracted US medical school characteristics and ranked schools based on the percentages of women graduates entering neurosurgery. They additionally studied yearly trends of the percentage of women constituting incoming neurosurgery resident cohorts as well as associations between female recruitment percentage and medical school characteristics using univariable and stepwise multivariable linear regression (including significant univariable factors).

RESULTS

The cohort consisted of 1255 male and 317 (20%) female residents. Yearly trends indicated a significant drop in incoming female residents in 2016, followed by significant increases in 2017 and 2019. On multivariable analysis, the following factors were associated with a higher average percentage of female graduates entering neurosurgery: total affiliated neurosurgery clinical faculty (β = 0.006, 95% CI 0.001–0.011, p = 0.01), allopathic versus osteopathic schools (β = 0.231, 95% CI 0.053–0.409, p = 0.01), and top 10 U.S. News & World Report ranking (β = 0.380, 95% CI 0.129–0.589, p < 0.01). When the number of female clinical faculty was added to the model, the variable was not statistically significant. Multivariable bibliometric analyses indicated a higher mean preresidency H-index for men, with an even greater gender difference identified in the 2021 H-index.

CONCLUSIONS

This study characterizes which medical schools are most successful at recruiting female students who constituted the total neurosurgery resident workforce of the 2020–2021 academic year. The overall number of clinical neurosurgery faculty rather than faculty gender was independently associated with female recruitment. Gender differences in research productivity persisted with control for confounders and increased between preresidency and 2021 time points. Such understanding of factors that influence the recruitment of women can help improve female representation in neurosurgery residency training moving forward.

ABBREVIATIONS

AΩA = Alpha Omega Alpha medical honor society; AAMC = American Association of Medical Colleges; AANS = American Association of Neurological Surgeons; ACGME = Accreditation Council for Graduate Medical Education; IMG = international medical graduate; PGY = postgraduate year; US News = U.S. News & World Report.

OBJECTIVE

The authors aimed to characterize which US medical schools have the most female neurosurgery residents and to identify potential associations between medical school characteristics and successful recruitment of women pursuing a neurosurgery career.

METHODS

The authors evaluated a total of 1572 residents in US neurosurgery programs accredited by the Accreditation Council for Graduate Medical Education as of February 2021, representing match cohorts from 2014 to 2020. The authors extracted US medical school characteristics and ranked schools based on the percentages of women graduates entering neurosurgery. They additionally studied yearly trends of the percentage of women constituting incoming neurosurgery resident cohorts as well as associations between female recruitment percentage and medical school characteristics using univariable and stepwise multivariable linear regression (including significant univariable factors).

RESULTS

The cohort consisted of 1255 male and 317 (20%) female residents. Yearly trends indicated a significant drop in incoming female residents in 2016, followed by significant increases in 2017 and 2019. On multivariable analysis, the following factors were associated with a higher average percentage of female graduates entering neurosurgery: total affiliated neurosurgery clinical faculty (β = 0.006, 95% CI 0.001–0.011, p = 0.01), allopathic versus osteopathic schools (β = 0.231, 95% CI 0.053–0.409, p = 0.01), and top 10 U.S. News & World Report ranking (β = 0.380, 95% CI 0.129–0.589, p < 0.01). When the number of female clinical faculty was added to the model, the variable was not statistically significant. Multivariable bibliometric analyses indicated a higher mean preresidency H-index for men, with an even greater gender difference identified in the 2021 H-index.

CONCLUSIONS

This study characterizes which medical schools are most successful at recruiting female students who constituted the total neurosurgery resident workforce of the 2020–2021 academic year. The overall number of clinical neurosurgery faculty rather than faculty gender was independently associated with female recruitment. Gender differences in research productivity persisted with control for confounders and increased between preresidency and 2021 time points. Such understanding of factors that influence the recruitment of women can help improve female representation in neurosurgery residency training moving forward.

In Brief

The authors used univariable and stepwise multivariable linear regression to study yearly trends for women entering neurosurgery residency programs from 2014 to 2020 and associations between recruitment percentages for women and medical school characteristics, with the aim of providing insights into reducing gender disparities. Important findings were that a top 10 U.S. News & World Report ranking was the most important independent factor predicting percentages of female medical school graduates entering a neurosurgery residency program. During the study period, the Cleveland Clinic had the most graduating women neurosurgery residents.

From 2008 onward, at least half of medical students across the US have been women.1 Despite nationwide efforts to increase the recruitment of women into surgical fields, gender imbalances persist across a wide spectrum of surgical residencies. In the 2007–2008 academic year, the five specialty residencies with the greatest degree of female underrepresentation were all surgical: otolaryngology, plastic surgery, urology, orthopedic surgery, and neurosurgery, which was the specialty with the least amount of women (11.15%).2 Neurosurgery remained the specialty with the second least amount of female representation (17.82%) in 2017–2018, and trend analyses projected that gender parity in neurosurgery, measured against female representation in the overall US trainee population, will not be achieved until the year 2056.2 By the end of 2018, only 53.2% of Accreditation Council for Graduate Medical Education (ACGME)–accredited neurosurgery residency programs had both female faculty and female residents.3 Beyond recruitment, the retention of women in surgery represents an additional challenge, with female residents being more likely than male residents to leave their surgical training programs, commonly citing an uncontrollable lifestyle and a desire to transfer to another specialty, such as anesthesiology.4 In parallel, higher attrition rates were reported among female than male neurosurgery residents in a nationwide study.5 Likewise, medical student interest in neurosurgery also varies throughout medical school and by gender. For instance, 2.2% of the 2016 entering medical school class was initially interested in neurosurgery.6 By graduation, only 1.1% of the 2020 medical school class intended to pursue neurosurgery—an attrition rate of 50%.7 Research also indicates that female medical students are less likely than male students to have an interest in surgery or a surgical subspeciality at the start of medical school (OR 0.42, 95% CI 0.40–0.44). By the end of medical school, female medical students are still less likely than male students to have an interest in surgery or a surgical subspeciality (OR 0.64, 95% CI 0.561–0.727), but by less of a margin.8 Strategies to address such imbalances and other challenges have been devised and include a focus on mentorship/sponsorship programs and conference scholarships, the establishment of "Women in Surgery" organizations, and awareness efforts regarding burnout.9 In the absence of multivariable quantitative analyses targeting the early recruitment stage from medical school to residency, the development of an effective plan to bridge gender gaps may prove difficult. In the present study, we explored which US medical schools have been most successful in recruiting female medical students to the traditionally male-dominated specialty of neurosurgery. In our analysis, we also sought to determine medical school characteristics associated with successful recruitment of women. Finally, we aimed to characterize potential bibliometric disparities, given the widespread emphasis placed on research in the field and its importance in career advancement.

Methods

Approval for this project was obtained from the Johns Hopkins Medicine Institutional Review Board.

Resident Cohort

We accessed the American Association of Neurological Surgeons (AANS) neurosurgical residency training program directory to obtain a list of ACGME-accredited residency training programs in neurosurgery while excluding Canadian programs. We generated a list of neurosurgery residents (postgraduate years [PGYs] 1 through 7) from publicly available web pages of the included US programs, which were accessed during February 2021. The resident cohort represented successfully matched medical school applicants over the 2014–2020 match cycles.

Resident Characteristics

For every resident, we recorded demographic information including gender, residency program name, PGY, medical school name with year of graduation, international medical graduate (IMG) status, degrees obtained, and Alpha Omega Alpha medical honor society (AΩA) membership (https://www.alphaomegaalpha.org). Website information was supplemented with publicly available data from Google Scholar, LinkedIn, Doximity, and DocInfo.

We compiled bibliometric data for each resident through the author search tool in Web of Science (Clarivate Analytics). We collected the total number of published papers, abstracts, and citations and the H-index during February 2021 and at the preresidency level (by the end of medical school), by filtering according to medical school graduation date. If publications had different names belonging to the same author, Web of Science allowed the merging of multiple author profiles.

Medical School Characteristics

Once we produced a list of feeder medical schools for neurosurgery (2014–2020), we collected characteristics for every feeder school located in the US while excluding international medical schools owing to incomplete data for a large number of schools and because the top feeder schools are US based. We extracted the total number of accredited allopathic and osteopathic medical schools from the American Association of Medical Colleges (AAMC) website (https://www.aamc.org/data-reports/faculty-institutions/report/us-medical-school-revenues) and the American Association of Colleges of Osteopathic Medicine website (https://www.aacom.org/become-a-doctor/u-s-colleges-of-osteopathic-medicine). We obtained medical school class size from the AAMC (https://apps.aamc.org/msar-ui/#/landing) and from the respective school web pages. Geographical data constituted the state in which every medical school was located and the regions (West, Midwest, South, and Northeast) as categorized by the US Census Bureau (https://www.census.gov/geographies/reference-maps/2010/geo/2010-census-regions-and-divisions-of-the-united-states.html). Comparisons with the AANS neurosurgery residency training programs list and supplementary online queries were used to ascertain which medical schools had a neurosurgery residency training program. From department web pages we extracted the total number of clinical neurosurgery faculty as well as the number of female clinical neurosurgery faculty affiliated with each medical school. We additionally determined the presence of a neurosurgery interest group using the AANS directory of medical student chapters (https://www.aans.org/Trainees/Medical-Students/Chapter-Directory) and the medical school websites. We obtained the total reported NIH funding for each medical school in 2020 from the U.S. News & World Report (US News) website (https://www.usnews.com/best-graduate-schools/top-medical-schools/most-research-money-rankings) and from the Blue Ridge Institute for Medical Research website (http://www.brimr.org/NIH_Awards/2020/default.htm). We recorded information regarding the reputations of affiliated neurosurgery departments by determining whether the affiliated hospital was ever ranked in the top 10 best US News rankings for neurology and neurosurgery from 2014 until 2020. Using the Doximity Residency Navigator tool, we also recorded top 10 reputation rankings for affiliated neurosurgery programs in 2021; moreover, we extracted the top 30–ranked programs in research output according to Doximity, which measures the collective H-index of program alumni.

Statistical Analysis

We summarized resident cohort characteristics using descriptive statistics (number and percentage for categorical variables and mean and standard deviation for continuous variables) while comparing men and women (chi-square and Fisher exact tests used as appropriate). To obtain an estimate of the number of graduating female medical students from each feeder school over the 7-year period, we multiplied the class size by 7 and subsequently divided by 2. This was based on AAMC data extracted from the Medical School Admission Requirements website (https://mec.aamc.org/msar-ui/#/landing), whereby having a subscription account allows the user to query the gender breakdown of every medical school, indicating a 1:1 male-to-female ratio in the vast majority of schools. Subsequently, we ranked the medical schools according to the percentage of female graduates pursuing and matching into neurosurgery over the 7-year period. We evaluated the yearly trend in the percentage of women constituting every incoming neurosurgery resident cohort using a chi-square test with post hoc comparisons between individual years (Bonferroni adjustment). We then created a heat map of the percentage of female graduates entering neurosurgery across the US organized by state. This heat map was created by entering our data into Google Geocharts under the following freely accessible link: https://www.danielpinero.com/how-to-create-heat-map-united-states?lang=en.

Using Pearson’s correlation coefficient (PCC) and the independent-samples t-test as appropriate, we evaluated associations between the percentage of female graduates entering neurosurgery and medical school characteristics. We used univariable and stepwise multivariable linear regression of univariable significant factors to identify medical school characteristics that were independently associated with the percentage of female graduates matching into neurosurgery. The absence of multicollinearity between variables in the multivariable model was verified by checking whether the variance inflation factor for all possible variable pairs was less than 3, especially for the total numbers of all neurosurgery clinical faculty and the number of female clinical faculty. To identify the relative importance of every variable, standardized β values were derived. We also performed univariable and multivariable gender comparisons of preresidency and 2021 bibliometric data using the independent-samples t-test and linear regression. We performed statistical analyses using SPSS software (version 25.0; IBM Corp.) with statistical significance set at p < 0.05.

Results

Resident Characteristics

The complete resident cohort in US ACGME-accredited neurosurgery programs reflecting matched applicants over the 2014–2020 match periods consisted of 1572 residents. Resident demographic characteristics compared by gender are summarized in Supplemental Digital Appendix 1. There were 317 (20%) women and 113 (7%) IMGs. Degrees held were generally similar between both genders, and there was a trend toward a higher proportion of AΩA members among men (29% vs 24%, p = 0.08).

Top Feeder Schools for Women

The 165 US medical schools that contributed at least 1 neurosurgery resident over the 7-year period contributed an average of 1.8 ± 2.1 (median 1, IQR 0–3) female residents per school. These 165 schools included 140 allopathic schools (99% of all allopathic schools [n = 141]) and 25 osteopathic schools (68% of all osteopathic schools [n = 37]). Of these, a total of 112 (68%) schools contributed at least 1 female neurosurgery resident. The mean percentage of female medical graduates going into neurosurgery from 2014 to 2020 among the 165 schools was 0.37% ± 0.44% (median 0.24%, IQR 0–0.54%) per school. The top US feeder schools for female neurosurgery residents are summarized in Table 1. The top 12 schools (7%) in recruitment had more than 1% of their female graduates going into neurosurgery. The percentages of women constituting the yearly incoming neurosurgery resident cohort dropped significantly from 16.5% in 2015 to 13.8% in 2016, after which a significant increase occurred in 2017 and 2019 (Fig. 1). Characteristics of feeder schools are summarized in Supplemental Digital Appendix 2.

TABLE 1.

Top feeder American medical schools ranked by percentage of women graduates going into neurosurgery during the 2014–2020 match period

RankMedical SchoolStudents Entering NS, %Women Grads Entering NS, No.Women Grads Entering NS, %
1Cleveland Clinic Lerner College of Medicine3.57132.679
2Case Western Reserve University School of Medicine3.106131.736
3Yale School of Medicine2.85761.714
4New York University School of Medicine3.22161.681
5Stanford University School of Medicine3.17551.587
6Harvard Medical School2.21191.531
7Louisiana State University School of Medicine2.38181.524
8Johns Hopkins University School of Medicine2.12561.417
9University of Illinois College of Medicine, Urbana0.59521.190
10Duke University School of Medicine2.45951.171
11Rutgers New Jersey Medical School2.64871.124
12Washington University in St. Louis School of Medicine1.78641.099
13Cooper Medical School of Rowan University0.81230.974
14University of Pittsburgh School of Medicine1.91850.959
15Geisel School of Medicine at Dartmouth1.27030.952
16Vanderbilt University School of Medicine3.79930.912
17Albany Medical College1.78640.893
18University of California, San Diego, School of Medicine1.71940.859
19University of Tennessee College of Medicine1.17650.840
20University of Wisconsin School of Medicine1.00350.835
21Emory University School of Medicine1.23340.822
22Texas Tech University Health Sciences Center El Paso Paul L. Foster School of Medicine1.42930.779
23Keck School of Medicine of the University of Southern California1.15250.768
24Virginia Commonwealth University School of Medicine1.30650.768
25Northeast Ohio Medical University0.66240.757
26Rush Medical College0.92240.737
27Medical College of Georgia at Augusta University0.89360.714
28Georgetown University School of Medicine1.61950.704
29University of Kentucky College of Medicine0.62750.697
30New York Medical College1.01150.674
31Brody School of Medicine at East Carolina University0.66420.664
32University of California, Los Angeles, David Geffen School of Medicine1.38840.653
33University of Florida College of Medicine1.48130.635
34University of Illinois College of Medicine, Chicago0.95240.635
35University of Texas Southwestern School of Medicine1.00350.627
36Baylor College of Medicine1.15240.614
37Wake Forest School of Medicine0.78830.591
38Zucker School of Medicine at Hofstra/Northwell0.57720.577
39Oregon Health & Science University0.76230.571
40Boston University School of Medicine0.75230.564
41University of California, Irvine, School of Medicine0.68720.549
42University of South Carolina School of Medicine Greenville0.52920.529
43University of Connecticut School of Medicine0.51920.519
44Robert Wood Johnson Medical School0.65730.493
45University of Arizona College of Medicine, Tucson0.97720.488
46The University of Toledo College of Medicine0.81230.487
47Wright State University School of Medicine0.36320.484
48Saint Louis University School of Medicine0.54630.468
49University of Alabama at Birmingham School of Medicine1.61330.461
50University of Missouri–Kansas City School of Medicine0.69120.461
51Oakland University William Beaumont School of Medicine0.57120.457
52Florida Atlantic University Charles E. Schmidt College of Medicine0.89310.446
53University of Illinois College of Medicine, Peoria0.87910.440
54University of Nebraska College of Medicine1.09120.436
55Columbia University College of Physicians and Surgeons2.95920.408
56Icahn School of Medicine at Mount Sinai0.91820.408
57University of Texas Health Science Center at San Antonio1.14630.404
58East Tennessee State University James H. Quillen College of Medicine0.39710.397
59City University of New York Medical School (Sophie Davis School of Biomedical Education)0.37610.376
60University of Pennsylvania Perelman School of Medicine1.47520.369
61University of Virginia School of Medicine1.10620.369
62University of Louisville School of Medicine0.89820.359
63Marshall University Joan C. Edwards School of Medicine0.89310.357
64Northwestern Feinberg School of Medicine0.71420.357
65Loyola University of Chicago Stritch School of Medicine0.95220.346
66Drexel University College of Medicine0.65930.330
67Texas A&M University Health Science Center College of Medicine0.49020.327
68University of California, San Francisco, School of Medicine1.04320.321
69Sidney Kimmel Medical College at Thomas Jefferson University1.00530.317
70University of Cincinnati College of Medicine1.02020.314
71Indiana University School of Medicine0.93940.313
72Albert Einstein College of Medicine0.70320.312
73George Washington University School of Medicine0.69920.311
74Quinnipiac University–Frank H. Netter School of Medicine0.45610.304
75Rosalind Franklin University/Chicago Medical School1.36120.302
76Michigan State University College of Osteopathic Medicine0.68030.292
77University of Miami Miller School of Medicine1.40120.280
78University of Rochester School of Medicine1.40110.280
79Ohio State University College of Medicine0.97620.279
80Central Michigan University College of Medicine0.27710.277
81Mayo Medical School1.22410.272
82Lewis Katz School of Medicine at Temple University0.98320.262
83Howard University College of Medicine0.23810.238
84University of Texas Medical School at Houston0.95220.238
85University of Minnesota Medical School0.59320.237
86Florida International University Herbert Wertheim College of Medicine0.69710.232
87University of Vermont College of Medicine0.92210.230
88University of Utah School of Medicine0.80010.229
89University of Missouri School of Medicine0.22310.223
90Touro University College of Osteopathic Medicine, New York0.31710.212
91University of Pikeville–Kentucky College of Osteopathic Medicine0.21210.212
92Warren Alpert Medical School of Brown University1.29010.198
93Campbell University School of Osteopathic Medicine0.09510.190
94Pennsylvania State University College of Medicine0.84610.188
95University of Colorado School of Medicine0.82910.184
96State University of New York Upstate Medical University0.89310.179
97University of Oklahoma College of Medicine0.95810.174
98Uniformed Services University0.67610.169
99Medical University of South Carolina College of Medicine0.66110.165
100Jacobs School of Medicine and Biomedical Sciences0.55610.159
101Edward Via College of Osteopathic Medicine0.23210.154
102University of South Florida Morsani College of Medicine0.90710.151
103Tulane University School of Medicine0.52610.150
104University of North Carolina at Chapel Hill School of Medicine0.59210.148
105Tufts University School of Medicine0.92910.143
106Midwestern University–Chicago College of Osteopathic Medicine0.27910.139
107University of Kansas School of Medicine0.33910.135
108University of Texas Medical School at Galveston0.49710.124
109Lake Erie College of Osteopathic Medicine0.28610.114
110New York Institute of Technology College of Osteopathic Medicine0.21210.106
111University of Washington School of Medicine0.26510.106
112Western University of Health Sciences College of Osteopathic Medicine0.13110.087

Grads = graduates; NS = neurosurgery.

FIG. 1.
FIG. 1.

Yearly trend in the percentage of women in incoming neurosurgery cohorts (n = 1572). Overall chi-square p < 0.01; horizontal lines separate years with significantly different female student enrollment. Figure is available in color online only.

The mean number of clinical neurosurgery faculty affiliated with each medical school was 13.0 ± 14.1 (median 9, IQR 0–19). There was a significant correlation between the number of faculty members and the percentage of female graduates going into neurosurgery (PCC = 0.385, p < 0.01). On linear regression, an absolute increase of 0.012 percentage points (95% CI 0.008%–0.016%, p < 0.01) in female graduates entering neurosurgery was identified per clinical faculty member increase (Supplemental Digital Appendix 3). A similar univariable association was detected with the number of female clinical neurosurgery faculty (Supplemental Digital Appendix 4). Some medical schools with no affiliated female neurosurgery faculty still had a relatively large percentage of female medical graduates entering neurosurgery. A geographic representation of female recruitment into neurosurgery by state is provided in the form of a heat map (Fig. 2). Although all US regions had recruitment hubs, medical schools in the Northeastern states had the highest recruitment rates (84% recruited at least 1 woman) compared to those in Western states, which had the lowest recruitment rates (50% recruited at least 1 woman).

FIG. 2.
FIG. 2.

A heat map by state for average percentages of female graduates entering neurosurgery. *Indicates states without medical schools. This map was created using Google GeoCharts. Figure is available in color online only

Univariable medical school characteristics significantly associated with percentage of women entering neurosurgery included clinical faculty size, number of female clinical faculty, presence of a neurosurgery interest group and a home neurosurgery residency program at the medical school, allopathic school type, US News ranking of affiliated neurology and neurosurgery departments, and Doximity reputation ranking (Table 2). A stepwise linear regression model revealed that the number of clinical neurosurgery faculty (β = 0.006, 95% CI 0.001–0.011, p = 0.01), allopathic school type (β = 0.231, 95% CI 0.053–0.409, p = 0.01), and top 10 US News ranking (β = 0.380, 95% CI 0.148–0.612, p < 0.01) were independently and positively associated with the percentage of women entering neurosurgery. Upon adding the number of female clinical neurosurgery faculty to this model, this variable was not significantly associated with the percentage of female graduates entering neurosurgery. None of the following variables exhibited collinearity: neurosurgery clinical faculty, number of female clinical neurosurgery faculty, allopathic versus osteopathic school type, and US News top 10 ranking (variance inflation factor < 3 in all pairs).

TABLE 2.

Univariable and stepwise multivariable linear regression analysis of the percentages of female graduates entering neurosurgery (n = 165 medical schools)

VariableUnivariableMultivariable
β (95% CI)p Valueβ (95% CI)p Value
No. of neurosurgery clinical faculty0.012 (0.008 to 0.016)<0.01*0.006 (0.001 to 0.011)0.013*
No. of female clinical neurosurgery faculty0.063 (0.034 to 0.091)<0.01*
Neurosurgery interest group0.309 (0.158 to 0.461)<0.01*
Home neurosurgery program0.317 (0.189 to 0.445)<0.01*
Allopathic vs osteopathic school0.360 (0.181 to 0.540)<0.01*0.231 (0.053 to 0.409)0.01*
US News top 10 (2014–2020)0.559 (0.340 to 0.777)<0.01*0.380 (0.129 to 0.589)<0.01*
Doximity top 10 (2021)0.428 (0.138 to 0.718)<0.01*
NIH funding in 2020, per $1 billion0.728 (0.454 to 1.002)<0.001*
Geographic region (West as reference)0.28
 Northeast0.195 (−0.030 to 0.420)0.09
 Midwest0.133 (−0.089 to 0.355)0.24
 South0.057 (−0.150 to 0.264)0.59

Statistically significant (p < 0.05).

Standardized β coefficients: clinical faculty size (0.206), allopathic school (0.190), US News ranking (0.250).

Bibliometric Characteristics

Bibliometric comparisons by gender are summarized in Table 3 for 1563 residents with available data. The average preresidency H-index was 0.5 points higher for men (3.4 ± 4.0 vs 2.9 ± 3.1, p = 0.03). This difference increased to 0.8 points when the 2021 H-index was assessed (4.7 ± 4.5 vs 3.9 ± 3.3, p < 0.01). On multivariable analysis, the gender difference persisted for preresidency H-index when we controlled for IMG status, PhD degree, MS degree, and graduating from a medical school affiliated with a top 30 Doximity research output program (preresidency H-index less in women by 0.5 [95% CI 0.02–0.9], p = 0.04). Concerning H-index values in 2021, women still had a significantly lower H-index with a wider difference compared to preresidency after we adjusted for IMG status, PhD degree, MS degree, graduating from a medical school affiliated with a top 30 Doximity research output program, going to a top 30 Doximity research output residency program, and PGY (H-index lower by 0.7 [95% CI 0.2–1.2] for women, p < 0.01).

TABLE 3.

Bibliometric characteristics (n = 1563) by gender (2014–2020 match cycles)

VariableMen (n = 1247)Women (n = 316)p Value
Preresidency
 Published papers & abstracts8.6 ± 13.77.5 ± 10.00.11
 Citations137.7 ± 336.297.9 ± 212.3<0.01*
 H-index3.4 ± 4.02.9 ± 3.10.03*
2021
 Published papers & abstracts18.2 ± 23.313.3 ± 15.0<0.01*
 Citations188.1 ± 460.6125.0 ± 238.4<0.01*
 H-index4.7 ± 4.53.9 ± 3.3<0.01*

Statistically significant (p < 0.05).

Gender differences persisted on multivariable linear regression with adjustment for IMG status, PhD and MS degrees for preresidency H-index, and graduating from medical schools affiliated with top 30 Doximity research output residency programs, and with adjustment for IMG status, PhD degree, MS degree, graduating from medical schools affiliated with top 30 Doximity research output residency programs, being in a top 30 Doximity research output residency program, and PGY for 2021 H-index.

Discussion

Our results clarify which medical schools are most successful in recruiting female medical students into a traditionally male-dominated surgical specialty. Standardizing our metrics to class size was necessary in order to capture medical school recruitment efforts; larger medical schools will naturally have more women entering the field regardless of recruitment efforts. Medical school characteristics that were independently associated with female recruitment included the number of affiliated clinical neurosurgery faculty, allopathic school type, and US News top 10 ranking. A gender gap in publications existed at the preresidency time period and increased by 2021, even with adjustment for confounding variables. While it appears that female medical student recruitment may be trending up over time, our analysis suggests that this process may be happening far too slowly. Alternatively, female recruitment may be oscillating around a mean, with 2017 and 2019 recruitment data acting as outliers. This situation is occurring despite concerted recruitment efforts already implemented. Given these findings, we suggest that more disruptive mechanisms may be necessary to increase female recruitment. One potential avenue to pursue includes recruitment and exposure efforts directed toward female medical students at matriculation, when interest in a surgical specialty is widest among students of both genders.8

Affiliated Departmental Faculty: Does Gender Matter?

Although a higher number of affiliated clinical neurosurgery faculty was independently associated with increased female recruitment, the number of women faculty members was not. The univariable association between the number of women faculty and recruitment was likely the result of confounding: larger and more highly ranked affiliated neurosurgery departments were more likely to have an increased number of employed female faculty. One possible explanation for our findings, put forward by Benzil et al. in a 2008 White Paper Committee article, is that female faculty have yet to reach a “critical mass” of 15%, whereby under this threshold they act more as isolated individuals as opposed to a unified minority group.10 This effect may have an impact on the influence of women faculty on female medical students interested in neurosurgery. One possibility is that female medical students may view female neurosurgery faculty as isolated, an observation that may discourage them from pursuing the field. Moreover, with fewer female faculty to act as mentors, less diversity among the cohort of women neurosurgeons is expected, which may impact the ability of female medical students to connect with mentors. We hypothesize that a larger and more diverse female workforce would positively impact the recruitment of female medical students into the field. Another possibility is that female medical students seek high-quality mentorship, regardless of faculty gender. A greater number of available mentors may have increased the likelihood of finding and establishing mentor-mentee relationships that promoted interest in the field of neurosurgery. Finally, gender bias may lead to male faculty being relatively better able to successfully match mentees into neurosurgery, a situation that might offset the benefit of having more access to female neurosurgeons as possible mentors.

These findings mirror survey-based data published in 2020 by McNutt et al.11 Among 105 active female neurosurgery residents in 2019 (44% response rate among female residents), the residency program characteristics considered least important when choosing a residency program were gender diversity of faculty and residents, number of female residents, number of female faculty, and attitudes toward maternity leave. The most important attributes were caseload and variety, resident happiness and well-being, early surgical experience, and academic reputation.11 Similar results were reported in 2020 by Goss et al. in the field of orthopedic surgery based on a survey of 158/305 (52% response rate) female residents. Gender diversity of faculty and residents, number of female residents, and number of female faculty were reported to be among the least influential factors in deciding on a residency program.12 These findings, taken together, suggest that overall mentorship quality and opportunity in surgical fields ought to be emphasized in addition to gender diversity in order to maximize female medical student interest and successful recruitment.

Disparity in Research Productivity

Our findings demonstrate a greater H-index for male neurosurgery residents, with disparity starting during medical school and increasing with time throughout residency. In 2017, a bibliometric analysis of 1506 neurosurgical residents in North America conducted by Khan et al. indicated that men had higher overall and intraresidency H-indices than women, but no multivariable analysis was conducted.13 Preresidency bibliometric analyses have been conducted in neurosurgery, but no gender comparisons were performed.14,15 On univariable analysis, preresidency total publications were associated with a PhD degree and attending a medical school affiliated with a department that was highly ranked in research; no multivariable analysis was conducted.14 A positive univariable correlation between medical student first-author publications and the number of affiliated neurosurgery faculty was also previously described.15 Our analysis confirms that gender disparities arise at an early stage in medical training independently from differences in degree attainment, IMG status, or affiliated institution research ranking. It remains unclear, however, if preresidency publication metrics accurately predict performance and academic success during and after residency, and this topic deserves further study. Bibliometric profiles during residency are significantly associated with a future academic career path, attaining full professorship, and becoming a departmental chair or chief.16 Critically, it is not enough to simply recruit more female medical students into neurosurgery; it is also necessary to enable them to attain prominent, visible positions of leadership in order to positively influence the field from the top down. Hence, a deeper understanding is required of the contributing factors (e.g., comparatively lower interest in research among women vs fewer mentorship and funding opportunities available to women) behind the start and perpetuation of gender disparity in surgical academic productivity and its downstream effects.

Implications Moving Forward

For stakeholders interested in improving the recruitment of female medical students into neurosurgery and likely other surgical subspecialties, the data presented herein may serve as a guide. Medical schools in several states, such as New Mexico, Nevada, Idaho, North and South Dakota, Iowa, Arkansas, Mississippi, and Maine, have not had female medical students join the total neurosurgery resident workforce of the 2020–2021 academic year. Medical schools in the West, as a whole, have the most potential to increase female recruitment. As such, organizational efforts aimed at promoting recruitment of women may have the most to gain from focusing on such regions. It is, however, important to note that educational missions may vary among medical schools, with some schools aiming to recruit students into primary care as opposed to neurosurgery. Such motivations must be taken into account when engaging in recruitment efforts.

Additionally, larger departments have a higher chance of recruiting female medical students by offering more opportunities for strong partnerships with mentors to develop. Departments that emphasize mentorship qualities and skills in their clinical faculty hiring practices, in addition to gender diversification strategies, may maximize the chances of attracting more women medical students into the field. Similar quantitative analyses centered on recruitment patterns in other surgical subspecialties, such as plastic surgery, orthopedic surgery, and otolaryngology, remain warranted. In recognition of the crucial role that women have played in the progress of neurosurgery abroad, including regions such as Asia, Australasia, Latin America, and India,1719 comparable analyses and data curation efforts must be established internationally.

Overall, based on our findings, we suggest three recommendations that we believe may have an immediate impact on female recruitment and career advancement. First, efforts should be focused on introducing the field of neurosurgery to female medical students at matriculation, when the gender gap in surgical specialty interest is widest.8 In turn, these efforts may encourage female students who otherwise may not have been interested in neurosurgery to begin exploring the field, thus enabling them to get an early start in developing more competitive applications and dispelling negative notions they may have had about the field. Second, research fellowships and opportunities should be specifically targeted to female neurosurgery residents, as our data show that gender disparities in research productivity widen during residency. Finally, concerted efforts should be made to create female neurosurgery groups comprising faculty, residents, and medical students at each institution. Groups such as these may enable female medical students to view women neurosurgeons as a unified minority as opposed to dispersed individuals and may help minimize the 15% critical mass threshold described by Benzil et al.,10 which may be required for more robust recruitment of women neurosurgeons.

Study Limitations

Our findings must be interpreted with caution. Data regarding applicants who were interested in neurosurgery but who failed to match during the 7-year study period were missed. Addition of this information to percentage entry into the field would reflect not only interest in the field, but also the ability to match successfully. Arguably, however, successful recruitment of medical students into surgical fields is more important as an outcome measure than merely promoting interest in pursuing surgical training. In addition, our data captured female neurosurgery residents who trained during the 2020–2021 academic year; it did not, however, account for residents who may have matched in positions beyond PGY-1 or who may have matched but subsequently discontinued training, possibilities to which a small amount of attrition may be attributed. Another limitation is our assumption that all medical school male-to-female student ratios are exactly one to one. While this is generally true for the vast majority of medical schools, in some programs the ratios may vary by a small percentage. Our study was also limited in its inability to capture nonbinary individuals or to confirm the gender identity that each resident associates with; this shortcoming was primarily due to the heterogeneity of data for each resident profile on different program websites. Finally, our data only represent contemporary trends; it may be worthwhile to track even larger cohorts over a longer period of time.

Conclusions

This study characterizes which medical schools are most successful at recruiting female students into the current resident workforce of a traditionally gender-imbalanced specialty. The overall number of clinical faculty rather than faculty gender was independently associated with female recruitment. Gender differences in research productivity persisted with control for confounders and increased between preresidency and 2021 time points. Increased understanding of the manifestations of gender disparities can help improve female representation in neurosurgery residency training moving forward, a need that remains crucially unmet, while providing a data curation and analysis model that can be used to address disparities in other surgical subspecialties.

Disclosures

Dr. Witham reports direct stock ownership and medical advisory board membership in Augmedics. Dr. Huang reports direct stock ownership in Longeviti. Dr. Brem acts as a consultant for Acuity Bio Corp., Insightec, Accelerating Combination Therapies, Catalio Nexus Fund II, LikeMinds, Galen Robotics, and Nurami Medical.

Author Contributions

Conception and design: Huang, Feghali, Antar, Witham, Brem. Acquisition of data: Feghali, Antar, Wicks, Sattari, Li. Analysis and interpretation of data: Feghali, Antar. Drafting the article: Feghali, Antar. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Huang. Statistical analysis: Huang, Feghali. Study supervision: Huang, Witham, Brem.

Supplemental Information

Online-Only Content

Supplemental material is available with the online version of the article.

Previous Presentations

Portions of this work were included in an oral presentation at the Congress of Neurological Surgeons 2021 Annual Meeting, Austin, Texas, October 16–20, 2021.

References

  • 1

    Sexton KW, Hocking KM, Wise E, et al. Women in academic surgery: the pipeline is busted. J Surg Educ. 2012;69(1):8490.

  • 2

    Bennett CL, Baker O, Rangel EL, Marsh RH. The gender gap in surgical residencies. JAMA Surg. 2020;155(9):893894.

  • 3

    Donaldson K, Callahan KE, Gelinne A, et al. Gender diversity in United States neurosurgery training programs. J Neurosurg. 2021;135(3):943948.

  • 4

    Khoushhal Z, Hussain MA, Greco E, et al. Prevalence and causes of attrition among surgical residents: a systematic review and meta-analysis. JAMA Surg. 2017;152(3):265272.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Lynch G, Nieto K, Puthenveettil S, et al. Attrition rates in neurosurgery residency: analysis of 1361 consecutive residents matched from 1990 to 1999. J Neurosurg. 2015;122(2):240249.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Association of American Medical Colleges. 2016 Matriculating Student Questionnaire. Association of American Medical Colleges;2016.

  • 7

    Association of American Medical Colleges. 2020 Graduation Questionnaire. Association of American Medical Colleges;2020.

  • 8

    Burkhardt J, DesJardins S, Gruppen L. Diversity of the physician workforce: specialty choice decisions during medical school. PLoS One. 2021;16(11):e0259434.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Stephens EH, Heisler CA, Temkin SM, Miller P. The current status of women in surgery: how to affect the future. JAMA Surg. 2020;155(9):876885.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 10

    WINS White Paper Committee; Benzil DL, Abosch A, Germano I, et al. The future of neurosurgery: a white paper on the recruitment and retention of women in neurosurgery. J Neurosurg. 2008;109(3):378386.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11

    McNutt SE, Goss ML, Hallan DR, Bible JE. Factors in residency decision making for female neurosurgery applicants. World Neurosurg. 2020;140:e105e111.

  • 12

    Goss ML, McNutt SE, Hallan DR, Bible JE. Factors in orthopaedic residency decision-making for female applicants: a cross-sectional study. J Am Acad Orthop Surg. 2020;28(24):10551060.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13

    Khan NR, Saad H, Oravec CS, et al. An analysis of publication productivity during residency for 1506 neurosurgical residents and 117 residency departments in North America. Neurosurgery. 2019;84(4):857867.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14

    Wadhwa H, Shah SS, Shan J, et al. The neurosurgery applicant’s “arms race”: analysis of medical student publication in the Neurosurgery Residency Match. J Neurosurg. 2020;133(6):19131921.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 15

    Price G, Lakomkin N, Kamat S, Baron RB, Scherschinski L, Hadjipanayis C. Medical student publications in neurosurgery: at which U.S. academic institutions do medical students publish most? World Neurosurg. 2021;147:181189.e1.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16

    Crowley RW, Asthagiri AR, Starke RM, Zusman EE, Chiocca EA, Lonser RR. In-training factors predictive of choosing and sustaining a productive academic career path in neurological surgery. Neurosurgery. 2012;70(4):10241032.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17

    Palanisamy D, Battacharjee S. What it is to be a woman neurosurgeon in India: a survey. Asian J Neurosurg. 2019;14(3):808814.

  • 18

    Zanon N, Niquen-Jimenez M, Kim EE, et al. Progress in neurosurgery: contributions of women neurosurgeons in Latin America. J Clin Neurosci. 2021;86:347356.

  • 19

    Drummond KJ, Kim EE, Apuahe E, et al. Progress in neurosurgery: contributions of women neurosurgeons in Asia and Australasia. J Clin Neurosci. 2021;86:357365.

  • Collapse
  • Expand

Figure from Ramos et al. (pp 95–103).

  • View in gallery
    FIG. 1.

    Yearly trend in the percentage of women in incoming neurosurgery cohorts (n = 1572). Overall chi-square p < 0.01; horizontal lines separate years with significantly different female student enrollment. Figure is available in color online only.

  • View in gallery
    FIG. 2.

    A heat map by state for average percentages of female graduates entering neurosurgery. *Indicates states without medical schools. This map was created using Google GeoCharts. Figure is available in color online only

  • 1

    Sexton KW, Hocking KM, Wise E, et al. Women in academic surgery: the pipeline is busted. J Surg Educ. 2012;69(1):8490.

  • 2

    Bennett CL, Baker O, Rangel EL, Marsh RH. The gender gap in surgical residencies. JAMA Surg. 2020;155(9):893894.

  • 3

    Donaldson K, Callahan KE, Gelinne A, et al. Gender diversity in United States neurosurgery training programs. J Neurosurg. 2021;135(3):943948.

  • 4

    Khoushhal Z, Hussain MA, Greco E, et al. Prevalence and causes of attrition among surgical residents: a systematic review and meta-analysis. JAMA Surg. 2017;152(3):265272.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Lynch G, Nieto K, Puthenveettil S, et al. Attrition rates in neurosurgery residency: analysis of 1361 consecutive residents matched from 1990 to 1999. J Neurosurg. 2015;122(2):240249.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Association of American Medical Colleges. 2016 Matriculating Student Questionnaire. Association of American Medical Colleges;2016.

  • 7

    Association of American Medical Colleges. 2020 Graduation Questionnaire. Association of American Medical Colleges;2020.

  • 8

    Burkhardt J, DesJardins S, Gruppen L. Diversity of the physician workforce: specialty choice decisions during medical school. PLoS One. 2021;16(11):e0259434.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Stephens EH, Heisler CA, Temkin SM, Miller P. The current status of women in surgery: how to affect the future. JAMA Surg. 2020;155(9):876885.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 10

    WINS White Paper Committee; Benzil DL, Abosch A, Germano I, et al. The future of neurosurgery: a white paper on the recruitment and retention of women in neurosurgery. J Neurosurg. 2008;109(3):378386.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11

    McNutt SE, Goss ML, Hallan DR, Bible JE. Factors in residency decision making for female neurosurgery applicants. World Neurosurg. 2020;140:e105e111.

  • 12

    Goss ML, McNutt SE, Hallan DR, Bible JE. Factors in orthopaedic residency decision-making for female applicants: a cross-sectional study. J Am Acad Orthop Surg. 2020;28(24):10551060.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13

    Khan NR, Saad H, Oravec CS, et al. An analysis of publication productivity during residency for 1506 neurosurgical residents and 117 residency departments in North America. Neurosurgery. 2019;84(4):857867.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14

    Wadhwa H, Shah SS, Shan J, et al. The neurosurgery applicant’s “arms race”: analysis of medical student publication in the Neurosurgery Residency Match. J Neurosurg. 2020;133(6):19131921.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 15

    Price G, Lakomkin N, Kamat S, Baron RB, Scherschinski L, Hadjipanayis C. Medical student publications in neurosurgery: at which U.S. academic institutions do medical students publish most? World Neurosurg. 2021;147:181189.e1.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16

    Crowley RW, Asthagiri AR, Starke RM, Zusman EE, Chiocca EA, Lonser RR. In-training factors predictive of choosing and sustaining a productive academic career path in neurological surgery. Neurosurgery. 2012;70(4):10241032.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17

    Palanisamy D, Battacharjee S. What it is to be a woman neurosurgeon in India: a survey. Asian J Neurosurg. 2019;14(3):808814.

  • 18

    Zanon N, Niquen-Jimenez M, Kim EE, et al. Progress in neurosurgery: contributions of women neurosurgeons in Latin America. J Clin Neurosci. 2021;86:347356.

  • 19

    Drummond KJ, Kim EE, Apuahe E, et al. Progress in neurosurgery: contributions of women neurosurgeons in Asia and Australasia. J Clin Neurosci. 2021;86:357365.

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