Social determinants of health and outcome disparities in spine tumor surgery. Part 1: An analysis of 6.6 million nationwide admissions

OBJECTIVE Earlier research has demonstrated that social determinants of health (SDoH) impact neurosurgical access and outcomes, but these trends are less characterized for spine tumors relative to intracranial tumors. The authors aimed to elucidate the association between SDoH and outcomes for a nationwide cohort of spine tumor surgery admissions. METHODS The authors identified all admissions with a spine tumor diagnosis in the National Inpatient Sample (NIS) from 2002 to 2019. Four SDoH were analyzed: race and ethnicity, insurance, household income, and safety-net hospital (SNH) treatment. Hospitals in the top quartile of safety-net burden (in terms of percentage of patients receiving Medicaid or uninsured) were categorized as SNHs. Multivariable regression queried the association between 22 variables and 5 perioperative outcomes: mortality, discharge disposition, complications, length of stay (LOS), and hospitalization costs. Interaction term analysis with hospitalization year was used to assess longitudinal changes in outcome disparities. Finally, the authors constructed random forest machine learning models to assess the impact of SDoH variables on prognostic accuracy and to quantify the relative importance of predictors for disposition. RESULTS Of 6,593,392 total admissions with spine tumors, 219,380 (3.3%) underwent surgery. Non-White race (OR 0.80–0.91, p < 0.001) and nonprivate insurance (OR 0.76–0.83, p < 0.001) were associated with lower odds of receiving surgery. Among surgical admissions, presenting severity, including of myelopathy and plegia, was elevated among non-White, nonprivate insurance, and low-income admissions (all p < 0.001). Black race (OR 0.70, p < 0.001), Medicare (OR 0.70, p < 0.001), Medicaid (OR 0.90, p < 0.001), and lower income (OR 0.88–0.93, all p < 0.001) were associated with decreased odds of favorable discharge disposition. Increased LOS and costs were observed among non-White (+6%–10% in LOS and +5%–9% in costs, both p < 0.001) and Medicaid (+16% in LOS and +6% in costs, both p < 0.001) admissions. SNH treatment was also associated with higher mortality (OR 1.49, p < 0.001) and complication (OR 1.20, p < 0.001) rates. From 2002 to 2019, disposition improved annually for Medicaid patients (OR 1.03 per year, p = 0.022) but worsened for Black patients (OR 0.98 per year, p = 0.046). Random forest models identified household income as the most important predictor of discharge disposition. CONCLUSIONS For spine tumor admissions, SDoH predicted surgical intervention, presenting severity, and perioperative outcomes. Over 2 decades, disparities improved for Medicaid patients but worsened for Black patients. Finally, SDoH significantly improve prognostic accuracy for outcomes after spine tumor surgery. Further study toward ameliorating patient disparities for this population is warranted.