The association of regional intensity of neurosurgical care with spinal fusion surgery in the USA.
OBJECTIVE
There is wide regional variability in the volume of procedures performed for similar surgical patients throughout the USA. The purpose of this study was to investigate the association of spinal fusion operations with several socioeconomic factors.


METHODS
We performed a retrospective cohort study involving patients who underwent any neurosurgical procedure from 2005 to 2010 and were registered in National Inpatient Sample (NIS). A sub-cohort of patients undergoing spinal operations was also created. Regression techniques were used to investigate the association of the average intensity of neurosurgical care (defined as the average number of neurosurgical procedures per capita) with the average rate of fusions.


RESULTS
In the study period, there were 707,951 patients undergoing spinal procedures, who were registered in NIS. There were significant disparities in the fusion rate among different states (ANOVA, P < 0.0001), which ranged from 0.41 in Maine, where non-fusion surgeries were very predominant, to 0.62 in Virginia, where fusion was the main treatment modality used. In a multivariate analysis, the intensity of neurosurgical care was associated with an increased fusion rate. A similar effect was observed for coverage by private insurance, higher income, urban hospitals, large hospital size, African American patients, and patients with less comorbidities. Hospital location in the northeast was associated with a lower rate in comparison to the midwest, and south. Coverage by Medicaid was associated with lower fusion rate.


CONCLUSIONS
We observed significant disparities in the integration of fusion operations in spine surgery practices in the USA. Increased intensity of neurosurgical care was associated with a higher fusion rate.
Section of Neurosurgery, Dartmouth-Hitchcock Medical Center, One Medical Center Dr., Lebanon, NH, 03756, USA, kbekelis@gmail.com.
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D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D054625:Healthcare Disparities / Q000706:statistics & numerical data*; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012959:Socioeconomic Factors; D013123:Spinal Fusion / Q000706:statistics & numerical data*; D014481:United States