Part I: The application of the h-index to groups of individuals and departments in academic neurosurgery

Objective: The h-index was introduced as a means of quantifying the contribution a researcher makes to the scientific literature. We evaluated the h-index for academic neurosurgeons to assess the various methods of calculation and to determine whether the h-index can be used to differentiate groups of individuals by various classifications.

Methods: The h-index was calculated for all neurosurgeons from 10 institutions ranked highly by 2012 U.S. News & World Report plus the authors' institution via Scopus. The h-index also was calculated manually to evaluate its accuracy. The average h-index was calculated for groups on the basis of sex, academic rank, years in practice, institution, and subspecialty. Cumulative and mean h-indices were calculated for each department.

Results: The median h-index for the 188 neurosurgeons was 16 (mean, 19.71; range, 0-61). There was a positive association between the h-index, academic rank, and years posttraining. There was a significant difference between the "manually calculated" and automated h-indices, particularly for more senior physicians. The difference in h-index between men and women was not statistically significant. Among subspecialties, vascular surgeons had the greatest average h-index and general neurosurgeons had the lowest. There were significant shifts in departmental rankings when the cumulative or mean departmental indices were compared with the U.S. News & World Report rankings.

Conclusion: Application of the h-index as a bibliometric in neurosurgery can distinguish academic productivity on the basis of academic rank, years posttraining, and neurosurgical subspecialties. The application of the h-index to compare departments is problematic and, at this time, not reliable.