The global neurosurgical workforce: a mixed-methods assessment of density and growth.

OBJECTIVE: In 2000, the global density of neurosurgeons was estimated at 1 per 230,000 population, which remains the most recent estimate of the global neurosurgeon workforce density. In 2004, the World Health Organization (WHO) estimated that there were 33,193 neurosurgeons worldwide, including trainees. There have been no updates to this estimate in the past decade. Moreover, only WHO region-level granularity regarding neurosurgeon distribution exists; country-level estimates are limited. The neurosurgery workforce is a crucial component to meeting the growing burden of neurosurgical diseases, which not only represent high absolute incidences and prevalences, but also represent correspondingly high disability-adjusted life years affecting hundreds of millions of people worldwide. Combining the lack of knowledge about the availability of the neurosurgical workforce and the increasing demand for neurosurgical services underscores the need for a system of neurosurgical workforce density surveillance. METHODS: This study involved 3 key steps: 1) global survey/literature review to obtain the number of working neurosurgeons per WHO-recognized country, 2) regression to interpolate any missing data, and 3) calculation of workforce densities and comparison to available historical data by WHO region. RESULTS: Data for 198 countries were collected (158) or interpolated (40). The global total number of neurosurgeons was estimated at 49,940. Overall, neurosurgeon density ranged from 0 to 58.95 (standardized to per 1,000,000 population) with a median of 3.56 (IQR 0.29-8.26). Thirty-three countries were found to have no neurosurgeons (zero). The highest density, 58.95, was in Japan, where 7495 neurosurgeons are taking care of a population of 127,131,800. CONCLUSIONS: In 2015, the Lancet Commission on Global Surgery estimated that 143 million additional surgical procedures are needed in low- and middle-income countries each year, and a subsequent study revealed that approximately 15% of those surgical procedures are neurosurgical. Based on our results, we can conclude that there are approximately 49,940 neurosurgeons currently, worldwide. The availability of neurosurgeons appears to have increased in all geographic regions over the past decade, with Southeast Asia experiencing the greatest growth. Such remarkable expansion should be assessed to determine factors that could play a role in other regions where the acceleration of growth would be beneficial.