Global Trends in the Neurosurgical Literature: A 20-Year Bibliometric Analysis by Country Income Group.

Abstract

Despite growing global interest in neurosurgical equity, research output remains concentrated in high-income countries (HICs), with limited representation from lower-middle-income countries (LMICs). Although the global neurosurgery movement has highlighted these disparities, its impact on authorship and research equity is unclear. This study uses bibliometric analysis to evaluate 20-year trends in neurosurgical publications, focusing on authorship patterns across World Bank income groups. A bibliometric analysis of publications with topic of "neurosurgery" indexed in the Web of Science database from 2005 to 2024 was conducted. Author affiliations were categorized by World Bank income classifications: HIC, upper-middle-income countries, LMICs, and low-income countries (LICs). Lorenz curves and Gini coefficients were used to assess inequality in research output, and the Mann-Kendall trend test evaluated trends over time. A total of 27 391 neurosurgical publications from 170 countries were analyzed. HICs contributed 80.55% of overall authorship and 77.16% of corresponding authorship. By contrast, LICs contributed just 2.54% of overall authorship and 0.33% of corresponding authorship. Multicountry collaborations accounted for 26.13% of all publications, of which 95.37% included HIC authors, whereas only 9.14% included LIC authors. From 2005 to 2024, the share of corresponding authorship from HICs declined from 86.16% to 58.88%, whereas contributions from upper-middle-income countries, LMICs, and LICs rose significantly (P < .001). Overall, Gini coefficients improved from 0.74 in 2005 to 0.61 in 2023, indicating a modest but statistically significant reduction in research inequality over time (tau = -0.79, P < .001). Despite a 4-fold increase in publication volume and rising international collaboration, neurosurgical research remains heavily dominated by HICs. While authorship equity has modestly improved over the past 2 decades, disparities remain stark, especially for LICs. These findings highlight the need for targeted, sustainable efforts to promote equitable research partnerships, capacity building, and lower-middle-income country leadership in global neurosurgery.