1429. Specialization Within Neurosurgery: Trends in Neurosurgical Fellowship Training Between 1997 and 2016 in North America

Authors: Ankush Chandra; Michael Brandel, BA; Manish Aghi, MD, PhD (San Francisco, CA)

Introduction: Neurosurgical training programs serve to create both general practitioners and subspecialists. To define trends in producing both, we investigated trends in neurosurgical fellowship enrollment in North America. Methods: Retrospective review of North American neurosurgery residents enrolled in training between 1997-2016, assessed using AANS membership data. Results: We followed 3,619 North American neurosurgical residency graduates over 20 years, of which 40.7% (n=1,472) completed a fellowship and 4.8% (n=175) completed at least two different fellowships. Of completed fellowships, 27.2% (n=456) were in spine, 14.6% (n=245) were endovascular, 14.0% (n=235) were pediatric, 9.6% (n=161) were functional, 8.7% (n=146) were skull base, 8.7% (n=146) were open cerebrovascular, 7.2% (n=122) were neuro-oncology, 6.2% (n=104) other, 1.6% (n=26) neurotrauma, 1.4% (n=24) peripheral nerve, and 0.7% (n=11) combined endovascular/open cerebrovascular fellowships. The overall proportion of residents pursuing fellowships significantly increased from 1997-2006 to 2007-2016 (29.1 vs. 49.6%, p<0.001). On linear regression, the proportion of spine, cerebrovascular, and trauma fellowships decreased by 0.5% (R-square=0.001, p=0.037), 0.3% (R-square=0.001, p=0.029), and 0.3% (R-square=0.004, p<0.001) per year, respectively, while the proportion of skull base, peripheral nerve, and combined endovascular/cerebrovascular fellowships increased by 0.5% (R-square=0.003, p=0.002), 0.2% (R-square=0.004, p=0.016) and 0.2% (R-square=0.008, p=0.001) per year, respectively. Interestingly, residents from top 40 NIH-funded institutions were more likely to complete fellowships in 2007-2016 (OR=1.5, p=0.004), whereas residents in high population cities were less likely to complete fellowships in 2007-2016 (OR=0.7, p=0.030). Conclusion: Over two decades, the percentage of neurosurgical residents pursuing fellowships has significantly increased with skull base, peripheral nerve and combined endovascular/cerebrovascular fellowships gaining popularity while spine, cerebrovascular and trauma fellowships have decreased in popularity, despite remaining the most common fellowships overall. In the last decade, residents from a top 40 NIH program or from programs in smaller cities were more likely to pursue neurosurgical fellowships, likely due to academic interest and clinical volume, respectively.