h_global-Index: A Novel Author-Level Measure of the Diffusion of Scientific Ideas Among High-, Low-, and Middle-Income Countries

Objective: To describe an intuitive and useful method for measuring the global impact of a medical scholar's research ideas by examining cross-border citations (CBCs) of peer-reviewed neurosurgical publications.

Methods: Publication and citation data for a random sample of the top 50 most academically productive neurosurgeons were obtained from Scopus Application Programming Interface. We characterized an author-level global impact index analogous to the widely used h-index, the h_global-index, defined as the number of published peer-reviewed manuscripts with at least the same number of CBCs. To uncover socioeconomic insights, we explored the h_global-index for high-, middle-, and low-income countries.

Results: The median (interquartile range) number of publications and CBCs were 144 (62-255) and 2704 (959-5325), respectively. The median (interquartile range) h-index and h_global-index were 42 (23-61) and 32 (17-38), respectively. Compared with neurosurgeons in the random sample, the 3 global neurosurgeons had the highest h_global-indices in low-income countries at 17, 13, and 9, despite below-average h-index scores of 33, 38, and 19, respectively.

Conclusion: This intuitive update to the h-index uses CBCs to measure the global impact of scientific research. The h_global-index may provide insight into global diffusion of medical ideas, which can be used for social science research, author self-assessment, and academic promotion.