Postgraduate publishing output in pediatric neurosurgery: correlation with fellowship site and individual scholars

Sonia Ajmera College of Medicine, and

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Ryan P. Lee Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland;

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Andrew Schultz College of Medicine, and

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David S. Hersh Department of Neurosurgery, The University of Tennessee Health Science Center, Memphis, Tennessee;

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Jacob Lepard Department of Neurosurgery, University of Alabama School of Medicine, Birmingham, Alabama;

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Raymond Xu College of Medicine, and

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Hassan Saad Arkansas Neuroscience Institute, CHI St. Vincent Infirmary, Little Rock, Arkansas;

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Olutomi Akinduro College of Medicine, and

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Melissa Justo College of Medicine, and

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Brittany D. Fraser College of Medicine, and

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Mustafa Motiwala College of Medicine, and

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Pooja Dave Rhodes College, Memphis, Tennessee;

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Brian Jimenez College of Medicine, and

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David A. Wallace College of Medicine, and

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Olufemi Osikoya College of Medicine, and

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Sebastian Norrdahl College of Medicine, and

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Jennings H. Dooley College of Medicine, and

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Nickalus R. Khan Department of Neurosurgery, The University of Tennessee Health Science Center, Memphis, Tennessee;

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Brandy N. Vaughn Le Bonheur Children’s Hospital, Memphis, Tennessee;

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Cormac O. Maher Department of Neurosurgery, University of Michigan, Ann Arbor, Michigan; and

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Paul Klimo Jr. Department of Neurosurgery, The University of Tennessee Health Science Center, Memphis, Tennessee;
Le Bonheur Children’s Hospital, Memphis, Tennessee;
Semmes Murphey, Memphis, Tennessee

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OBJECTIVE

The objective of this study was to analyze the publication output of postgraduate pediatric neurosurgery fellows for a 10-year period as well as identify 25 individual highly productive pediatric neurosurgeons. The correlation between academic productivity and the site of fellowship training was studied.

METHODS

Programs certified by the Accreditation Council for Pediatric Neurosurgery Fellowships that had 5 or more graduating fellows from 2006 to 2015 were included for analysis. Fellows were queried using Scopus for publications during those 10 years with citation data through 2017. Pearson correlation coefficients were calculated, comparing program rankings of faculty against fellows using the revised Hirsch index (r-index; primary) and Hirsch index (h-index; secondary). A list of 25 highly accomplished individual academicians and their fellowship training locations was compiled.

RESULTS

Sixteen programs qualified with 152 fellows from 2006 to 2015; 136 of these surgeons published a total of 2009 articles with 23,735 citations. Most publications were pediatric-specific (66.7%) clinical articles (93.1%), with middle authorship (55%). Co-investigators were more likely from residency than fellowship. There was a clustering of the top 7 programs each having total publications of around 120 or greater, publications per fellow greater than 12, more than 1200 citations, and adjusted ir10 (revised 10-year institutional h-index) and ih10 (10-year institutional h-index) values of approximately 2 or higher. Correlating faculty and fellowship program rankings yielded correlation coefficients ranging from 0.53 to 0.80. Fifteen individuals (60%) in the top 25 (by r5 index) list completed their fellowship at 1 of these 7 institutions.

CONCLUSIONS

Approximately 90% of fellowship-trained pediatric neurosurgeons have 1 or more publications, but the spectrum of output is broad. There is a strong correlation between where surgeons complete their fellowships and postgraduate publications.

ABBREVIATIONS

ACPNF = Accreditation Council for Pediatric Neurosurgery Fellowship; h-index = Hirsch index; ih5 = 5-year institutional h-index; ih10 = 10-year institutional h-index; ih10c = ih10 index corrected for the number of fellows who graduated from the program within the 10-year period; ir5 = revised 5-year institutional h-index; ir10 = revised 10-year institutional h-index; ir10c = ir10 index corrected for the number of fellows who graduated from the program within the 10-year period; r-index = revised h-index.

OBJECTIVE

The objective of this study was to analyze the publication output of postgraduate pediatric neurosurgery fellows for a 10-year period as well as identify 25 individual highly productive pediatric neurosurgeons. The correlation between academic productivity and the site of fellowship training was studied.

METHODS

Programs certified by the Accreditation Council for Pediatric Neurosurgery Fellowships that had 5 or more graduating fellows from 2006 to 2015 were included for analysis. Fellows were queried using Scopus for publications during those 10 years with citation data through 2017. Pearson correlation coefficients were calculated, comparing program rankings of faculty against fellows using the revised Hirsch index (r-index; primary) and Hirsch index (h-index; secondary). A list of 25 highly accomplished individual academicians and their fellowship training locations was compiled.

RESULTS

Sixteen programs qualified with 152 fellows from 2006 to 2015; 136 of these surgeons published a total of 2009 articles with 23,735 citations. Most publications were pediatric-specific (66.7%) clinical articles (93.1%), with middle authorship (55%). Co-investigators were more likely from residency than fellowship. There was a clustering of the top 7 programs each having total publications of around 120 or greater, publications per fellow greater than 12, more than 1200 citations, and adjusted ir10 (revised 10-year institutional h-index) and ih10 (10-year institutional h-index) values of approximately 2 or higher. Correlating faculty and fellowship program rankings yielded correlation coefficients ranging from 0.53 to 0.80. Fifteen individuals (60%) in the top 25 (by r5 index) list completed their fellowship at 1 of these 7 institutions.

CONCLUSIONS

Approximately 90% of fellowship-trained pediatric neurosurgeons have 1 or more publications, but the spectrum of output is broad. There is a strong correlation between where surgeons complete their fellowships and postgraduate publications.

In Brief

The authors analyzed publication output of postgraduate pediatric neurosurgery fellows for a 10-year period correlated with site of training, and determined the current top 25 individual academicians in pediatric neurosurgery. To the authors’ knowledge, no studies have evaluated the association of where one completes his or her fellowship and subsequent academic output.

There has been growing interest in the application of bibliometric analyses to neurosurgery. Topics that have been explored include correlating measures of publishing output with academic rank, evaluating individual neurosurgeons and departments, and compiling the most highly cited articles in neurosurgery and various subfields.2,3,5,7–9,12,15,17,18,21,22,25,28,29,32,35,41,43 Additional studies have explored the correlation of bibliometrics with NIH funding,40 sex,13,39 and social media exposure.4,6,42 More advanced indices have been introduced that focus on discrete time periods in order to emphasize recent achievements (e.g., 5-year institutional Hirsch index [ih5]) and authorship rank in order to give greater recognition to differences in project investment (e.g., the revised h-index [r-index]).20,21,27,28,30,33,38 More recent publications have evaluated resident productivity.16,20,36

Within pediatric neurosurgery, publication productivity has been explored for individuals and departments using the h-index and its variants.15,24 We recently compared the publication productivity of faculty among the 28 pediatric neurosurgery fellowship programs using the ih5.28 In that study, we also introduced the ir5, which is analogous to the ih5, but takes authorship value into account by weighing first or last authorship 3 times more than middle authorship.

Bibliometrics has also been used as a means to determine what factors are associated with an individual choosing a career and excelling as an academician.1,9–11,31 In the present study, we sought to determine the cumulative research output of pediatric neurosurgeons sorted by where they completed their fellowship and compare that research output to the recent faculty-based institutional ranking. We also compiled a list of highly productive individual pediatric neurosurgeons to determine where these prolific contributors performed their fellowship training.

Methods

Study Design and Criteria

A list of accredited pediatric neurosurgery fellowship programs and their graduating fellows was obtained from the Accreditation Council for Pediatric Neurosurgery Fellowships (ACPNF; www.acpnf.org). Only programs with a minimum of 5 graduating fellows during our time period of interest (2006–2015) were included for analysis.

Each fellow was queried using Scopus (Elsevier), the largest abstract and citation database of peer-reviewed literature. Publications were collected from the year of fellowship completion, with the earliest possible year being 2006, until the year 2015. Only neurosurgical publications were included with careful screening to ensure each article was correctly affiliated with the appropriate fellow. Citation data for each fellow were collected through 2017 to allow additional time for citation accumulation, especially for fellows who graduated toward the later years in our study time period.

Data Variables

For each article, the following additional variables were collected: authorship value, specificity to pediatrics, study type, article subject, and program affiliation of other authors involved in the study. Authorship value indicated whether the fellow was first, middle, or last author. Articles were classified as being pediatric-specific or not, the latter focusing on either adult care only or a combination of adult and pediatric care. Study type used previously published definitions to differentiate between basic science or translational articles and clinical articles. Basic science articles center on the “acquisition of knowledge without obligation to apply it to practical ends,” while clinical articles are patient-oriented, including: “(a) mechanism of disease, (b) therapeutic interventions, (c) clinical trials, or (d) development of new technologies.”34 Translational research articles meld the two, endorsing the application of basic science research to clinical settings. Articles were further divided by subject: tumor, vascular, spine, trauma, functional/epilepsy, hydrocephalus, craniosynostosis, Chiari, peripheral nerve, and other, which included topics such as general surgical approaches, infection prevention, and imaging studies. Articles could fall into multiple categories.

To explore a fellow’s collaboration with other faculty, coauthors for each article were assessed to determine whether or not they were affiliated with either the same fellowship institution or the institution at which the fellow completed his or her residency. For those fellows who completed their fellowship at the same institution as their residency, coauthor credit was given to both the residency and fellowship, if applicable. A list of residency programs for the fellows was also obtained from the ACPNF.

Metrics and Rankings

An institutional Hirsch index (h-index) was calculated for each fellowship institution. The ih10 (institutional h-index for the 10-year period) is calculated as h number of publications collected from all fellows who graduated between 2006 and 2015, that had h citations collected over a 12-year period (2006–2017). The ih10 index was also corrected (ih10c) for the number of fellows who graduated from the program within our 10-year time period, yielding the average contribution toward the ih10 per graduated fellow.

To better assess the impact that a fellow had on research productivity, we continue to implement the new r-index. This metric weighs first or last authorship 3 times more than middle authorship, better reflecting the differing degrees of contribution of authors involved in research studies:

in which a represents the subset of articles h in which an author from the institution or program was first or last author.28 Similar to the ih10, an uncorrected ir10 and corrected ir10c was calculated for each institution. Rankings of graduated fellows were developed using the ih10 and ir10 and compared with previously published pediatric neurosurgery program faculty rankings based on the ih5 and ir5.28 The faculty rankings are based on the 5-year time period of 2011–2015.

Individual Scholars

Using the list of individual neurosurgeons compiled for our recent publication, all of whom are at ACPNF-approved programs, we updated their bibliometrics with Google Scholar and ranked them according to their 5-year (2012–2016) publications using the r-index (primary) and h-index (secondary). For the top 25 individuals on this list, we determined where they completed their pediatric fellowships, either through the AANS membership directory or on the faculty’s profile at his or her current practicing hospital or academic department. The number of years in practice was divided into 3 groups as follows: fellowship completion to < 10 years, 10 to < 20 years, and > 20 years.

Statistical Analysis

All statistical analyses were performed using Microsoft Excel. Mean and median numbers of citations per publication were calculated for each category or characteristic. The mean number of citations per publication was compared for each characteristic using the unpaired t-test. The central limit theorem allows for parametric testing with large sample sizes, such as ours.26 Program ranking by faculty was compared to program ranking by graduating fellows using linear regression (Pearson correlation coefficient). A p value ≤ 0.05 denoted significance in all statistical tests.

Results

Article Characteristics

Of the 16 qualifying programs with 152 fellows from 2006 to 2015, 7 programs had 16 fellows (11%) with no postgraduate publications. The remaining group of 136 fellows accounted for 2009 articles with 23,735 citations from 2006 to 2017 (Table 1). The mean number of citations per publication was 11.4 (range 0–585 citations).

TABLE 1.

Article characteristics (n = 2009)

Citations per Publication
CharacteristicNo. of Publications (%)No. of Citations (%)Mean/Medianp Value*
Pediatrics-specific<0.001
 Yes1341 (66.7)14,268 (60.1)10.6/6
 No668 (33.3)9467 (39.9)14.2/6
Authorship<0.001
 First or last903 (45.0)9030 (38.0)10.0/7
 Middle1106 (55.0)14,705 (62.0)13.3/6
Article type<0.001
 Clinical1871 (93.1)20,649 (87.0)11.0/6
 Basic/translational138 (6.9)3086 (13.0)22.4/10
Subject
 Functional/epilepsy170 (8.5)3050 (12.9)17.9/9Reference
 Tumor442 (22.0)6426 (27.1)14.5/60.261
 Vascular224 (11.2)2312 (9.7)10.3/6<0.001
 Spine462 (23.0)4443 (18.7)9.6/6<0.001
 Trauma153 (7.6)1890 (8.0)12.4/60.087
 Hydrocephalus280 (13.9)3166 (13.3)11.3/60.002
 Craniosynostosis64 (3.2)524 (2.2)8.2/40.008
 Chiari85 (4.2)942 (4.0)11.1/70.038
 Peripheral nerve33 (1.6)246 (1.0)7.5/50.038
 Other594 (29.6)6793 (28.6)11.4/60.001
Collaboration w/ fellowship faculty0.655
 Yes552 (27.5)6733 (28.4)12.2/8
 No1457 (72.5)17,002 (71.6)11.7/6
Collaboration w/ residency faculty<0.001
 Yes886 (44.1)13,354 (56.3)15.1/7
 No1123 (55.9)10,381 (43.7)9.3/5
Total2009 (100.0)23,735 (100.0)11.4

Statistical significance based on p < 0.05.

Articles could be categorized into more than one subject.

The majority of publications were pediatric-specific (66.7%) with the authorship position of the graduated fellow being slightly more often the middle author (55%) than first or senior (45%). Pediatric-specific articles had fewer average citations than nonpediatric (10.6 vs 14.2 citations, p < 0.001), but middle-author publications had greater average citations than first- or last-author publications (13.3 vs 10.0 citations, p < 0.001).

Clinical research articles predominated over basic science or translational research articles (93.1% vs 6.9%), but the latter acquired greater average citations (22.4 vs 11, p < 0.001). The subject category “other” was the most common (29.6%) and had the greatest number of citations (6793), while “functional/epilepsy” had the highest average number of citations (17.9).

Co-investigators were more commonly from the residency institution at which the fellow trained (44.1%) than from their fellowship institution (27.5%). There were 20 graduated fellows whose fellowship and residency institutions were the same. For these individuals, co-investigator credit was given to both residency and fellowship per applicable publication. Articles that contained coauthors affiliated with the fellow’s residency program had more citations per publication than those that did not (15.1 vs 9.3 citations, p < 0.001).

Program Metrics

Sixteen programs had 5 or more fellows during the time period of our analysis; 7 of these programs had 10 or more fellows (Table 2). The number of publications ranged from 21 to 376 while the number of publications per fellow ranged from 2.33 to 37.6. Citations per publication likewise had a broad range from 3.58 to 15.58.

TABLE 2.

Fellowship programs and rankings

PubsCitationsIndex
ir10cir10ih10cih10
Program*No. of FellowsTotalPer FellowTotalPer PubNo.RankNo.RankNo.RankNo.Rank
Boston Children’s Hospital1022322.30347415.582.64126.412.702271
Children’s Healthcare of Atlanta6254.172168.641.00136.0151.5011915
Children’s Hospital of Alabama813717.1313369.752.50220.042.503205
Children’s Hospital of Cincinnati9212.3330314.430.55164.4161.0015816
Children’s Hospital Los Angeles11524.724678.980.80148.8131.18141312
Children’s Hospital of Philadelphia9849.3393611.141.201110.8121.6791510
Children’s Hospital Pittsburgh910011.117647.641.42812.8101.56101411
Children’s Medical Center of Dallas14856.078269.720.63158.8130.93161312
Hospital for Sick Children1037637.60447711.912.20522.022.504253
Le Bonheur/St. Jude Children’s Hospital1015415.40181511.791.321013.291.808187
Lurie Children’s Hospital131037.92104110.111.201115.681.3812187
Nicklaus Children’s Hospital812115.134333.581.40911.2111.25131014
Primary Children’s Medical Center911913.22199916.801.96717.662.226205
Seattle Children’s Hospital913715.22263419.232.40321.633.001271
St. Louis Children’s Hospital1012812.80178013.911.96619.652.207224
Texas Children’s Hospital714420.5712348.572.34416.472.435179
Total152200913.2223,73511.81

Pub = publication.

Listed in alphabetical order.

Our primary ranking metric was the ir10c. All 16 programs were ranked, with ir10c values ranging from 0.55 to 2.64, with a median of 1.41. The median ih10c was 1.73 with a range of 0.93 to 3.00. As shown in Table 2, there was a clustering of the top 7 programs each with total publications of approximately 120 or greater, publications per fellow greater than 12, more than 1200 citations, and ir10c and ih10c values of about 2 or higher. The top 7 programs by both ir10c and ih10c were the following (in alphabetical order): 1) Boston Children’s Hospital; 2) Children’s Hospital of Alabama; 3) Hospital for Sick Children; 4) Primary Children’s Medical Center; 5) Seattle Children’s Hospital; 6) St. Louis Children’s Hospital; and 7) Texas Children’s Hospital.

Correlation Between Fellow and Faculty Program Rankings

When considering the 16 programs included in our current study and applying faculty program rankings from our previous study, the Pearson correlation coefficients were 0.53/0.55 when using the corrected r- and h-indices, respectively, and 0.80/0.73 when using the uncorrected r- and h-indices (Fig. 1).

FIG. 1.
FIG. 1.

Institutional faculty rankings compared with fellowship program rankings. Institutional rankings were based on r- and h-indices, accounting for a 5-year time period from 2011 to 2015, while fellowship program rankings were based on indices accounting for a 10-year time period from 2006 to 2015. A: Rankings based on uncorrected r-index, with a Pearson correlation coefficient of 0.80. B: Rankings based on r-index corrected for number of faculty or fellows at each institution, with a Pearson correlation coefficient of 0.53. C: Rankings based on uncorrected h-index, with a Pearson correlation coefficient of 0.73. D: Rankings based on h-index corrected for number of faculty or fellows, with a Pearson correlation coefficient of 0.55.

Individual Scholars

Tables 3 and 4 show the top 25 individual academic pediatric neurosurgeons ranked by the r-index (primary) and h-index (secondary), respectively. All were either in the middle (n = 15 [60%] and 14 [56%]; 10 to < 20 years) or late stage (> 20 years) of their career (n = 9 [36%] and 11 [44%]), except for one individual. Seven (Table 3) and 10 (Table 4) individuals either did not do a pediatric fellowship or completed one at a program that was not included in our study. The most common programs at which these individuals trained were the following: Hospital for Sick Children (n = 4/5), Boston Children’s Hospital (n = 4/2), St. Louis Children’s Hospital (n = 4/3), and Children’s Hospital of Alabama (n = 2/1). Fifteen (60%, Table 3) and 12 (48%, Table 4) neurosurgeons completed their fellowship at 1 of the 7 previously identified institutions.

TABLE 3.

Top 25 individual pediatric neurosurgeons by r5-index for publications from 2012 to 2016

Name*r5- IndexRankh5- IndexRankFellowship TrainingCurrent PracticeYrs in Practice
P. David Adelson14.0161718Boston Children’s HospitalPhoenix Children’s Hospital>20
Kurtis Auguste12.0221525Hospital for Sick ChildrenUCSF Benioff Children’s Hospital10–20
Frederick Boop14.8151914OtherLe Bonheur/St. Jude Children’s Hospital>20
Samuel Browd11.6241426Seattle Children’s HospitalSeattle Children’s Hospital10–20
Joshua Chern13.2181234Children’s Hospital of AlabamaChildren’s Healthcare of Atlanta<10
Peter Dirks16.011256OtherHospital for Sick Children>20
James Drake11.2251914OtherHospital for Sick Children>20
Richard Ellenbogen12.419227NoneSeattle Children’s Hospital>20
Nalin Gupta20.05292Hospital for Sick ChildrenUCSF Benioff Children’s Hospital>20
Andrew Jea18.871718Hospital for Sick ChildrenRiley Children’s Hospital10–20
Paul Klimo Jr.22.832110Boston Children’s HospitalLe Bonheur/St. Jude Children’s Hospital10–20
Abhaya Kulkarni19.66283OtherHospital for Sick Children10–20
David Limbrick15.2132012St. Louis Children’s HospitalSt. Louis Children’s Hospital10–20
Jeffrey Leonard13.617227St. Louis Children’s HospitalNationwide Children’s Hospital10–20
Jeffrey Ojemann16.8102110St. Louis Children’s HospitalSeattle Children’s Hospital10–20
Ian Pollack24.42283Children’s Hospital of PittsburghChildren’s Hospital of Pittsburgh>20
Shenandoah Robinson15.2131426St. Louis Children’s HospitalJohns Hopkins Hospital10–20
Curtis Rozzelle12.419227OtherChildren’s of Alabama10–20
James Rutka20.44275OtherHospital for Sick Children>20
Nathan Selden16.0111622Lurie Children’s HospitalOHSU Doernbecher Children’s Hospital10–20
Edward Smith12.4191332Boston Children’s HospitalBoston Children’s Hospital10–20
Matthew Smyth18.081816Children’s Hospital of AlabamaSt. Louis Children’s Hospital10–20
Michael Taylor35.61531Le Bonheur/St. Jude Children’s HospitalHospital for Sick Children10–20
Ben Warf17.291332Boston Children’s HospitalBoston Children’s Hospital>20
William Whitehead12.0221816Hospital for Sick ChildrenTexas Children’s Hospital10–20

Individual neurosurgeons are only from ACPNF-approved fellowship programs. Names listed in alphabetical order.

Years in practice since fellowship completion.

TABLE 4.

Top 25 individual pediatric neurosurgeons by h5-index for publications from 2012 to 2016

Name*h5- IndexRankr5- IndexRankFellowship TrainingCurrent PracticeYrs in Practice
P. David Adelson171814.016Boston Children’s HospitalPhoenix Children’s Hospital>20
Kurtis Auguste152512.022Hospital for Sick ChildrenUCSF Benioff Children’s Hospital10–20
Frederick Boop191414.815OtherLe Bonheur/St. Jude Children’s Hospital>20
Peter Dirks25616.011OtherHospital for Sick Children>20
James Drake191411.225OtherHospital for Sick Children>20
Richard Ellenbogen22712.419NoneSeattle Children’s Hospital>20
Gerald Grant1718828Seattle Children’s HospitalStanford Children’s Health10–20
Nalin Gupta29220.05Hospital for Sick ChildrenUCSF Benioff Children’s Hospital>20
Michael Handler1718828OtherChildren’s Hospital Colorado>20
George Jallo16227.632OtherJohns Hopkins All Children’s Hospital>20
Andrew Jea171818.87Hospital for Sick ChildrenRiley Children’s Hospital10–20
Paul Klimo Jr.211022.83Boston Children’s HospitalLe Bonheur/St. Jude Children’s Hospital10–20
Abhaya Kulkarni28319.66OtherHospital for Sick Children10–20
David Limbrick201215.213St. Louis Children’s HospitalSt. Louis Children’s Hospital10–20
Jeffrey Leonard22713.617St. Louis Children’s HospitalNationwide Children’s Hospital10–20
Joseph Madsen16226.435OtherBoston Children’s Hospital>20
Jeffrey Ojemann211016.810St. Louis Children’s HospitalSeattle Children’s Hospital10–20
Ian Pollack28324.44Children’s Hospital of PittsburghChildren’s Hospital of Pittsburgh>20
Jay Riva-Cambrin20129.226Hospital for Sick ChildrenAlberta Children’s Hospital10–20
Curtis Rozzelle22712.419OtherChildren’s of Alabama10–20
James Rutka27520.44OtherHospital for Sick Children>20
Nathan Selden162216.011Lurie Children’s HospitalOHSU Doernbecher Children’s Hospital10–20
Matthew Smyth1816188Children’s Hospital of AlabamaSt. Louis Children’s Hospital10–20
Michael Taylor53135.61Le Bonheur/St. Jude Children’s HospitalHospital for Sick Children10–20
William Whitehead181612.022Hospital for Sick ChildrenTexas Children’s Hospital10–20

Individual neurosurgeons are only from ACPNF-approved fellowship programs. Names listed in alphabetical order.

Years in practice since fellowship completion.

Discussion

Application of bibliometrics in neurosurgery continues to garner interest and evolve. Recently, there have been efforts to correlate publications at different time periods in an individual’s career with subsequent career direction or achievements. For example, Daniels et al. found that choosing an academic career was associated with having 2 or more publications during residency, an h-index ≥ 2 during residency, and having devoted research time before residency, but, surprisingly, not with pre-residency publications.11 On the other hand, McClelland did show that neurosurgery graduates with at least one pre-residency publication were 1.34 times more likely to choose an academic career than graduates without a pre-residency publication.31 Crowley et al. also demonstrated that the number of total publications and the number of first-author publications were associated with an academic career path.10 Jean and Felbaum reported that highly productive early-career neurosurgeons were more likely to have attended “elite” medical schools and residencies and work at prestigious universities, with the strongest correlation being the residency program.14

Subspecialty training (i.e., fellowship) has received less attention within the bibliometric literature. Sonig et al. gathered bibliometric data for 37 neuroendovascular programs across the US.37 They found that 10 of 37 departments had a cumulative h-index ≥ 54, with these “high-productivity” centers having more faculty members with a significantly higher mean faculty h-index. However, no studies to our knowledge have evaluated the association of where one does his or her fellowship and subsequent academic output.

Our Findings

While the number of pediatric neurosurgery fellowships has gradually grown over the years (currently at 31), only half had 5 or more graduating fellows in a 10-year period. Ten percent of the group did not publish after graduation but were still included in our analysis. Similar to our previous publication, the 136 graduated pediatric neurosurgery fellows with publications publish on pediatric topics approximately two-thirds of the time and have an almost equal distribution of middle authorship compared to first or senior authorship (55% vs 45%). Clinical research is far more common (> 90%), but basic science publications, not surprisingly, garner on average double the number of citations. However, we were somewhat surprised to find that graduated fellows more commonly collaborated with members of their residency program as opposed to their fellowship (44.1% vs 27.5%). While the number of years spent in residency is obviously greater than the 1-year fellowship, we assumed fellowship would have had more impact on subsequent research efforts.

The range of average publications per graduated fellow in each program was broad, ranging from 2.33 to 37.6. Seven programs shared similar attributes, including each with total publications of about 120 or greater, publications per fellow greater than 12, more than 1200 citations, and adjusted ir10 and ih10 values of approximately 2 or higher. The exact rank of each program was conditional on whether the r- or h-index was used. The major finding was the demonstration of a strong correlation between where one does his or her fellowship, as measured by faculty productivity obtained from our previous research, and postgraduate publication output. The correlation coefficients ranged from 0.53 to 0.80, with the uncorrected r- and h-indices having a stronger correlation than the corrected indices. This discrepancy likely reflects greater variation in the publication output among a group of graduated fellows compared to the faculty from that institution, with this difference magnified by the corrected indices.

We then updated individual publishing statistics for the years 2012–2016 and created lists of 25 highly published individuals (by r- and h-index)—“who’s who” list of academic pediatric neurosurgeons, all from ACPNF programs. When listed by our primary metric (r-index), 15 (60%) neurosurgeons performed their fellowship at 1 of the 7 programs described above, while 7 (28%) either did not participate in a recognized pediatric fellowship or did one at a facility that was not part of our study.

What drives an individual to publish after completion of their formal training? The reasons for this are likely multifactorial, but can be viewed simplistically in 2 ways: either you “have to,” or you “want to.” Nowadays, research and publications are an important element of matching into a residency, advancing through residency, and matching into a fellowship.11,23 Thereafter, publishing is strongly tied to promotion, funding, and gaining professional recognition both for the program and the individual. Hence, those individuals who seek these goals simply must publish. On the other hand, those who do not have these pressures publish out of a genuine interest or passion for advancing their chosen field.

Research is also a powerful tool through which one can mentor prospective neurosurgeons at any level of education (i.e., premedical or medical students, residents, fellows, and colleagues).19 It is our feeling that highly accomplished pediatric fellowship institutions attract and select like-minded candidates and further fuel already accomplished individuals. This indelible impact can then be transferred from the graduated fellow to future generations of aspiring academicians that he or she interacts with, resulting in a “pay-it-forward” model of success. An area of future research would be to investigate the association and possible impact between prefellowship and postfellowship research.

Strengths and Limitations

We have conducted a detailed analysis of publications of graduated pediatric neurosurgery fellows. This study was not specifically intended to provide insight on fellowship training or fellowship selection; however, each reader can apply the information herein to both of those topics. We excluded several institutions because they did not have at least 5 fellows over the 10-year period of our study. Although only neurosurgical research was counted, it is unlikely that any of the graduated fellows have substantial research outside of neurosurgery, and such research would really not be of interest for this type of analysis.

Scopus was used as the source of publishing information; other sources (Web of Science, Google Scholar) exist and there may be differences in output found from individual to individual, but we have previously demonstrated that these differences are typically small.22 While there is a surfeit of bibliometrics, we have chosen to focus on the r- and h-indices, which allows us to emphasize volume of work (i.e., number of publications), interest generated by the publication (i.e., citations), recent efforts (5- or 10-year time intervals), and degree of project involvement (i.e., authorship).

Our study is predominantly applicable to the US with only one training program—Hospital for Sick Children—located outside the US. Our list of 25 highly published individuals was based on our previous analysis of 28 fellowship programs, therefore pediatric neurosurgeons at nonfellowship programs were not included. We selected time periods (2006–2015 for fellow productivity, 2011–2015 for institutional faculty productivity, and 2012–2016 for individual faculty productivity) in an effort to provide the reader with current-era results. However, it is unclear how our results would have changed if we had gone further back in time. Lastly, there are important aspects of academia that cannot be quantitatively analyzed, such as teaching and programmatic development. However, publishing is, in a sense, the “validation” of one’s work among his or her peers and is a powerful and long-lasting medium through which the individual and program can gain academic recognition.

Conclusions

Fellowship-trained pediatric neurosurgeons are academically productive, with only 10% not publishing after completion of their training. However, the publishing output is decidedly variable. Highly productive fellowship programs produce pediatric neurosurgeons who, in general, continue being highly productive.

Acknowledgments

We wish to thank Andrew J. Gienapp (Neuroscience Institute, Le Bonheur Children’s Hospital, and Department of Neurosurgery, University of Tennessee Health Science Center, Memphis, Tennessee) for technical and copy editing; preparation of the manuscript, figures, and tables for publishing; and publication assistance. The Jackson Fogelman Pediatric Neurosurgery Research Fund supported this project.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Klimo, Ajmera, Lee. Acquisition of data: Ajmera, Schultz, Lepard, Xu, Saad, Akinduro, Justo, Fraser, Motiwala, Dave, Jimenez, Wallace, Osikoya, Norrdahl, Dooley, Vaughn. Analysis and interpretation of data: Klimo, Ajmera. Drafting the article: Klimo, Ajmera, Lee. Critically revising the article: Klimo, Ajmera, Lee, Hersh, Khan, Maher. Reviewed submitted version of manuscript: Klimo, Ajmera. Approved the final version of the manuscript on behalf of all authors: Klimo. Statistical analysis: Ajmera.

References

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    • Crossref
    • PubMed
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    Alfaifi A, AlMutairi O, Allhaidan M, Alsaleh S, Ajlan A: The top 50 most-cited articles on acoustic neuroma. World Neurosurg 111:e454e464, 2018

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    Almutairi O, Albakr A, Al-Habib A, Ajlan A: The top-100 most-cited articles on meningioma. World Neurosurg 107:10251032.e5, 2017

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    Alotaibi NM, Guha D, Fallah A, Aldakkan A, Nassiri F, Badhiwala JH, et al.: Social media metrics and bibliometric profiles of neurosurgical departments and journals: is there a relationship? World Neurosurg 90:574579.e7, 2016

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    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Alotaibi NM, Nassiri F, Badhiwala JH, Witiw CD, Ibrahim GM, Macdonald RL, et al.: The most cited works in aneurysmal subarachnoid hemorrhage: a bibliometric analysis of the 100 most cited articles. World Neurosurg 89:58 7592.e6, 2016

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    • Search Google Scholar
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    Bean JR: Altmetrics in scientific research: flash in the pan or transformative innovation? World Neurosurg 104:993995, 2017

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    Bohl MA, Ponce FA: Assessing the relevancy of highly cited works in neurosurgery. Part I: the 100 most relevant papers in neurosurgical journals. World Neurosurg 104:927938, 2017

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
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    Bohl MA, Turner JD, Little AS, Nakaji P, Ponce FA: Assessing the relevancy of “citation classics” in neurosurgery. Part II: foundational papers in neurosurgery. World Neurosurg 104:939966, 2017

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    • PubMed
    • Search Google Scholar
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    Campbell PG, Awe OO, Maltenfort MG, Moshfeghi DM, Leng T, Moshfeghi AA, et al.: Medical school and residency influence on choice of an academic career and academic productivity among neurosurgery faculty in the United States. Clinical article. J Neurosurg 115:380386, 2011

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    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 70:10241032, 2012

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    Daniels M, Garzon-Muvdi T, Maxwell R, Tamargo RJ, Huang J, Witham T, et al.: Preresidency publication number does not predict academic career placement in neurosurgery. World Neurosurg 101:350356, 2017

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    Hirsch JE: An index to quantify an individual’s scientific research output. Proc Natl Acad Sci U S A 102:1656916572, 2005

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    Jamjoom AA, Wiggins AN, Loan JJ, Emelifeoneu J, Fouyas IP, Brennan PM: Academic productivity of neurosurgeons working in the United Kingdom: insights from the H-index and its variants. World Neurosurg 86:287293, 2016

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
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    Jean WC, Felbaum DR: Impact of training and practice environment on academic productivity of early career academic neurosurgeons. World Neurosurg 121:e892e897, 2019

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    Kalra RR, Kestle JR: An assessment of academic productivity in pediatric neurosurgery. J Neurosurg Pediatr 12:262265, 2013

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    Kashkoush A, Prabhu AV, Tonetti D, Agarwal N: The Neurosurgery Match: a bibliometric analysis of 206 first-year residents. World Neurosurg 105:341347, 2017

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    Khan N, Thompson CJ, Choudhri AF, Boop FA, Klimo P Jr: Part I: The application of the h-index to groups of individuals and departments in academic neurosurgery. World Neurosurg 80:759765.e3, 2013

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    Khan NR, Lee SL, Brown M, Reding J, Angotti J, Lepard J, et al.: Highly cited works in skull base neurosurgery. World Neurosurg 83:403418, 2015

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    Khan NR, Rialon KL, Buretta KJ, Deslauriers JR, Harwood JL, Jardine DA: Residents as mentors: the development of resident mentorship milestones. J Grad Med Educ 9:551554, 2017

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20

    Khan NR, Saad H, Oravec CS, Norrdahl SP, Fraser B, Wallace D, et al.: An analysis of publication productivity during residency for 1506 neurosurgical residents and 117 residency departments in North America. Neurosurgery 84:857867, 2019

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Khan NR, Thompson CJ, Taylor DR, Gabrick KS, Choudhri AF, Boop FR, et al.: Part II: Should the h-index be modified? An analysis of the m-quotient, contemporary h-index, authorship value, and impact factor. World Neurosurg 80:766774, 2013

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Khan NR, Thompson CJ, Taylor DR, Venable GT, Wham RM, Michael LM II, et al.: An analysis of publication productivity for 1225 academic neurosurgeons and 99 departments in the United States. J Neurosurg 120:746755, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
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    Kistka HM, Nayeri A, Wang L, Dow J, Chandrasekhar R, Chambless LB: Publication misrepresentation among neurosurgery residency applicants: an increasing problem. J Neurosurg 124:193198, 2016

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24

    Klimo P Jr, Venable GT, Khan NR, Taylor DR, Shepherd BA, Thompson CJ, et al.: Bibliometric evaluation of pediatric neurosurgery in North America. J Neurosurg Pediatr 14:695703, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 25

    Knight J: Academic impact rankings of neurosurgical units in the U.K. and Ireland, as assessed with the h-index. Br J Neurosurg 29:637643, 2015

  • 26

    Kwak SG, Kim JH: Central limit theorem: the cornerstone of modern statistics. Korean J Anesthesiol 70:144156, 2017

  • 27

    Lee RP, Venable GT, Roberts ML, Parikh KA, Taylor DR, Khan NR, et al.: Five-year institutional bibliometric profiles for 119 North American neurosurgical residency programs: an update. World Neurosurg 95:565575, 2016

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 28

    Lee RP, Xu R, Dave P, Ajmera S, Lillard JC, Wallace D, et al.: Taking the next step in publication productivity analysis in pediatric neurosurgery. J Neurosurg Pediatr 21:655665, 2018

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 29

    Li L, Ma X, Pandey S, Deng X, Chen S, Cui D, et al.: The most-cited works in severe traumatic brain injury: a bibliometric analysis of the 100 most-cited articles. World Neurosurg 113:e82e87, 2018

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 30

    Lozano CS, Tam J, Kulkarni AV, Lozano AM: The academic productivity and impact of the University of Toronto Neurosurgery Program as assessed by manuscripts published and their number of citations. J Neurosurg 123:561570, 2015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 31

    McClelland S III: Pre-residency peer-reviewed publications are associated with neurosurgery resident choice of academic compared to private practice careers. J Clin Neurosci 17:287289, 2010

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 32

    Ponce FA, Lozano AM: Academic impact and rankings of American and Canadian neurosurgical departments as assessed using the h index. J Neurosurg 113:447457, 2010

  • 33

    Romanovsky AA: Revised h index for biomedical research. Cell Cycle 11:41184121, 2012

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    Rubio DM, Schoenbaum EE, Lee LS, Schteingart DE, Marantz PR, Anderson KE, et al.: Defining translational research: implications for training. Acad Med 85:470475, 2010

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
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    Saleem T: The Hirsch index—a play on numbers or a true appraisal of academic output? Int Arch Med 4:25, 2011

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    Sarkiss CA, Riley KJ, Hernandez CM, Oermann EK, Ladner TR, Bederson JB, et al.: Academic productivity of US neurosurgery residents as measured by H-index: program ranking with correlation to faculty productivity. Neurosurgery 80:975984, 2017

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 37

    Sonig A, Shallwani H, Levy BR, Shakir HJ, Siddiqui AH: Academic impact and rankings of neuroendovascular fellowship programs across the United States. J Neurosurg 127:11811189, 2017

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 38

    Taylor DR, Venable GT, Jones GM, Lepard JR, Roberts ML, Saleh N, et al.: Five-year institutional bibliometric profiles for 103 US neurosurgical residency programs. J Neurosurg 123:547560, 2015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 39

    Tomei KL, Nahass MM, Husain Q, Agarwal N, Patel SK, Svider PF, et al.: A gender-based comparison of academic rank and scholarly productivity in academic neurological surgery. J Clin Neurosci 21:11021105, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 40

    Venable GT, Khan NR, Taylor DR, Thompson CJ, Michael LM, Klimo P Jr: A correlation between National Institutes of Health funding and bibliometrics in neurosurgery. World Neurosurg 81:468472, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 41

    Venable GT, Shepherd BA, Roberts ML, Taylor DR, Khan NR, Klimo P Jr: An application of Bradford’s law: identification of the core journals of pediatric neurosurgery and a regional comparison of citation density. Childs Nerv Syst 30:17171727, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 42

    Wang J, Alotaibi NM, Ibrahim GM, Kulkarni AV, Lozano AM: The spectrum of altmetrics in neurosurgery: the top 100 “trending” articles in neurosurgical journals. World Neurosurg 103:883895.e1, 2017

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 43

    Wilkes FA, Akram H, Hyam JA, Kitchen ND, Hariz MI, Zrinzo L: Publication productivity of neurosurgeons in Great Britain and Ireland. J Neurosurg 122:948954, 2015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • Collapse
  • Expand
  • Institutional faculty rankings compared with fellowship program rankings. Institutional rankings were based on r- and h-indices, accounting for a 5-year time period from 2011 to 2015, while fellowship program rankings were based on indices accounting for a 10-year time period from 2006 to 2015. A: Rankings based on uncorrected r-index, with a Pearson correlation coefficient of 0.80. B: Rankings based on r-index corrected for number of faculty or fellows at each institution, with a Pearson correlation coefficient of 0.53. C: Rankings based on uncorrected h-index, with a Pearson correlation coefficient of 0.73. D: Rankings based on h-index corrected for number of faculty or fellows, with a Pearson correlation coefficient of 0.55.

  • 1

    Agarwal N, Clark S, Svider PF, Couldwell WT, Eloy JA, Liu JK: Impact of fellowship training on research productivity in academic neurological surgery. World Neurosurg 80:738744, 2013

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2

    Alfaifi A, AlMutairi O, Allhaidan M, Alsaleh S, Ajlan A: The top 50 most-cited articles on acoustic neuroma. World Neurosurg 111:e454e464, 2018

  • 3

    Almutairi O, Albakr A, Al-Habib A, Ajlan A: The top-100 most-cited articles on meningioma. World Neurosurg 107:10251032.e5, 2017

  • 4

    Alotaibi NM, Guha D, Fallah A, Aldakkan A, Nassiri F, Badhiwala JH, et al.: Social media metrics and bibliometric profiles of neurosurgical departments and journals: is there a relationship? World Neurosurg 90:574579.e7, 2016

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

    Alotaibi NM, Nassiri F, Badhiwala JH, Witiw CD, Ibrahim GM, Macdonald RL, et al.: The most cited works in aneurysmal subarachnoid hemorrhage: a bibliometric analysis of the 100 most cited articles. World Neurosurg 89:58 7592.e6, 2016

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

    Bean JR: Altmetrics in scientific research: flash in the pan or transformative innovation? World Neurosurg 104:993995, 2017

  • 7

    Bohl MA, Ponce FA: Assessing the relevancy of highly cited works in neurosurgery. Part I: the 100 most relevant papers in neurosurgical journals. World Neurosurg 104:927938, 2017

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Bohl MA, Turner JD, Little AS, Nakaji P, Ponce FA: Assessing the relevancy of “citation classics” in neurosurgery. Part II: foundational papers in neurosurgery. World Neurosurg 104:939966, 2017

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

    Campbell PG, Awe OO, Maltenfort MG, Moshfeghi DM, Leng T, Moshfeghi AA, et al.: Medical school and residency influence on choice of an academic career and academic productivity among neurosurgery faculty in the United States. Clinical article. J Neurosurg 115:380386, 2011

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10

    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 70:10241032, 2012

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Daniels M, Garzon-Muvdi T, Maxwell R, Tamargo RJ, Huang J, Witham T, et al.: Preresidency publication number does not predict academic career placement in neurosurgery. World Neurosurg 101:350356, 2017

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Hirsch JE: An index to quantify an individual’s scientific research output. Proc Natl Acad Sci U S A 102:1656916572, 2005

  • 13

    Jamjoom AA, Wiggins AN, Loan JJ, Emelifeoneu J, Fouyas IP, Brennan PM: Academic productivity of neurosurgeons working in the United Kingdom: insights from the H-index and its variants. World Neurosurg 86:287293, 2016

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

    Jean WC, Felbaum DR: Impact of training and practice environment on academic productivity of early career academic neurosurgeons. World Neurosurg 121:e892e897, 2019

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15

    Kalra RR, Kestle JR: An assessment of academic productivity in pediatric neurosurgery. J Neurosurg Pediatr 12:262265, 2013

  • 16

    Kashkoush A, Prabhu AV, Tonetti D, Agarwal N: The Neurosurgery Match: a bibliometric analysis of 206 first-year residents. World Neurosurg 105:341347, 2017

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

    Khan N, Thompson CJ, Choudhri AF, Boop FA, Klimo P Jr: Part I: The application of the h-index to groups of individuals and departments in academic neurosurgery. World Neurosurg 80:759765.e3, 2013

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18

    Khan NR, Lee SL, Brown M, Reding J, Angotti J, Lepard J, et al.: Highly cited works in skull base neurosurgery. World Neurosurg 83:403418, 2015

  • 19

    Khan NR, Rialon KL, Buretta KJ, Deslauriers JR, Harwood JL, Jardine DA: Residents as mentors: the development of resident mentorship milestones. J Grad Med Educ 9:551554, 2017

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20

    Khan NR, Saad H, Oravec CS, Norrdahl SP, Fraser B, Wallace D, et al.: An analysis of publication productivity during residency for 1506 neurosurgical residents and 117 residency departments in North America. Neurosurgery 84:857867, 2019

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Khan NR, Thompson CJ, Taylor DR, Gabrick KS, Choudhri AF, Boop FR, et al.: Part II: Should the h-index be modified? An analysis of the m-quotient, contemporary h-index, authorship value, and impact factor. World Neurosurg 80:766774, 2013

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Khan NR, Thompson CJ, Taylor DR, Venable GT, Wham RM, Michael LM II, et al.: An analysis of publication productivity for 1225 academic neurosurgeons and 99 departments in the United States. J Neurosurg 120:746755, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 23

    Kistka HM, Nayeri A, Wang L, Dow J, Chandrasekhar R, Chambless LB: Publication misrepresentation among neurosurgery residency applicants: an increasing problem. J Neurosurg 124:193198, 2016

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24

    Klimo P Jr, Venable GT, Khan NR, Taylor DR, Shepherd BA, Thompson CJ, et al.: Bibliometric evaluation of pediatric neurosurgery in North America. J Neurosurg Pediatr 14:695703, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 25

    Knight J: Academic impact rankings of neurosurgical units in the U.K. and Ireland, as assessed with the h-index. Br J Neurosurg 29:637643, 2015

  • 26

    Kwak SG, Kim JH: Central limit theorem: the cornerstone of modern statistics. Korean J Anesthesiol 70:144156, 2017

  • 27

    Lee RP, Venable GT, Roberts ML, Parikh KA, Taylor DR, Khan NR, et al.: Five-year institutional bibliometric profiles for 119 North American neurosurgical residency programs: an update. World Neurosurg 95:565575, 2016

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 28

    Lee RP, Xu R, Dave P, Ajmera S, Lillard JC, Wallace D, et al.: Taking the next step in publication productivity analysis in pediatric neurosurgery. J Neurosurg Pediatr 21:655665, 2018

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 29

    Li L, Ma X, Pandey S, Deng X, Chen S, Cui D, et al.: The most-cited works in severe traumatic brain injury: a bibliometric analysis of the 100 most-cited articles. World Neurosurg 113:e82e87, 2018

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 30

    Lozano CS, Tam J, Kulkarni AV, Lozano AM: The academic productivity and impact of the University of Toronto Neurosurgery Program as assessed by manuscripts published and their number of citations. J Neurosurg 123:561570, 2015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 31

    McClelland S III: Pre-residency peer-reviewed publications are associated with neurosurgery resident choice of academic compared to private practice careers. J Clin Neurosci 17:287289, 2010

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 32

    Ponce FA, Lozano AM: Academic impact and rankings of American and Canadian neurosurgical departments as assessed using the h index. J Neurosurg 113:447457, 2010

  • 33

    Romanovsky AA: Revised h index for biomedical research. Cell Cycle 11:41184121, 2012

  • 34

    Rubio DM, Schoenbaum EE, Lee LS, Schteingart DE, Marantz PR, Anderson KE, et al.: Defining translational research: implications for training. Acad Med 85:470475, 2010

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 35

    Saleem T: The Hirsch index—a play on numbers or a true appraisal of academic output? Int Arch Med 4:25, 2011

  • 36

    Sarkiss CA, Riley KJ, Hernandez CM, Oermann EK, Ladner TR, Bederson JB, et al.: Academic productivity of US neurosurgery residents as measured by H-index: program ranking with correlation to faculty productivity. Neurosurgery 80:975984, 2017

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 37

    Sonig A, Shallwani H, Levy BR, Shakir HJ, Siddiqui AH: Academic impact and rankings of neuroendovascular fellowship programs across the United States. J Neurosurg 127:11811189, 2017

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 38

    Taylor DR, Venable GT, Jones GM, Lepard JR, Roberts ML, Saleh N, et al.: Five-year institutional bibliometric profiles for 103 US neurosurgical residency programs. J Neurosurg 123:547560, 2015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 39

    Tomei KL, Nahass MM, Husain Q, Agarwal N, Patel SK, Svider PF, et al.: A gender-based comparison of academic rank and scholarly productivity in academic neurological surgery. J Clin Neurosci 21:11021105, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 40

    Venable GT, Khan NR, Taylor DR, Thompson CJ, Michael LM, Klimo P Jr: A correlation between National Institutes of Health funding and bibliometrics in neurosurgery. World Neurosurg 81:468472, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 41

    Venable GT, Shepherd BA, Roberts ML, Taylor DR, Khan NR, Klimo P Jr: An application of Bradford’s law: identification of the core journals of pediatric neurosurgery and a regional comparison of citation density. Childs Nerv Syst 30:17171727, 2014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 42

    Wang J, Alotaibi NM, Ibrahim GM, Kulkarni AV, Lozano AM: The spectrum of altmetrics in neurosurgery: the top 100 “trending” articles in neurosurgical journals. World Neurosurg 103:883895.e1, 2017

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 43

    Wilkes FA, Akram H, Hyam JA, Kitchen ND, Hariz MI, Zrinzo L: Publication productivity of neurosurgeons in Great Britain and Ireland. J Neurosurg 122:948954, 2015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation

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