Are There Racial or Socioeconomic Disparities in Ambulatory Outcome or Survival After Oncologic Spine Surgery for Metastatic Cancer? Results From a Medically Underserved Center
Authors: De la Garza Ramos Rafael , Javed Kainaat , Ryvlin Jessica , Gelfand Yaroslav , Murthy Saikiran , Yassari Reza 
Published: October 2022

Abstract

Background
Disparities among patients with cancer are well documented. Recent studies suggest these disparities also affect patients undergoing metastatic spinal tumor surgery. However, it is unclear whether social factors are associated with ambulatory outcomes or overall survival.

Questions/purposes
In patients undergoing metastatic spinal tumor surgery, (1) Are race, Social Vulnerability Index (SVI) score, or insurance status associated with a lower likelihood of postoperative ambulation? (2) Are race, SVI score, or insurance status associated with shorter overall survival?

Methods
Between April 2012 and June 2021, we surgically treated 148 patients for metastatic cord compression or spinal mechanical instability because of cancer. Inclusion criteria were patients with complete demographic, social, oncologic, and follow-up data and patients who were followed until death or for at least 3 months postoperatively. Based on these criteria, 12% (18 of 148) were excluded because they had incomplete data and another 7% (11 of 148) were excluded because they were lost before the minimum study follow-up interval, leaving 80% (119) for analysis. Collected social data included self-reported race (White, Black, Hispanic or Latino, or other), SVI score, and primary insurance (Medicare, Medicaid, or private). The median age of the group was 62 years (interquartile range [IQR] 53 to 70 years), and 58% of patients were men (69 of 119). The race distribution was 45% Black (54 of 119), 32% Hispanic or Latino (38 of 119), 16% White (19 of 119), and 7% other (eight of 119). The median SVI score was 89.8 (IQR 73.8 to 98.5), and 74% of patients (88) were categorized as having high vulnerability. The insurance distribution was as follows: Medicare: 43%, Medicaid: 36%, and private insurance: 21%. The primary outcome variable was complete inability to ambulate postoperatively and the secondary outcome was median overall survival. Exploratory data analysis, univariate and multivariate logistic regression, and univariate and multivariate Cox regression analyses were performed.

Results
After controlling for race, SVI score, insurance status, primary cancer, and modified Bauer score, the only factor independently associated with postoperative nonambulation was preoperative nonambulatory status (odds ratio 59.3 [95% confidence interval (CI) 13.2 to 266.1]; p < 0.001). After controlling for variables such as performance status, BMI, primary cancer, modified Bauer score, and insurance status, factors independently associated with survival included Eastern Cooperative Oncology Group performance status (hazard ratio [HR] 1.4 [95% CI 1.1 to 2.0]; p = 0.03), prostate cancer (HR 0.4 [95% CI 0.1 to 0.9]; p = 0.03), and hematologic cancer (HR 0.3 [95% CI 0.1 to 0.8]; p = 0.02). Race, SVI score, and insurance status were not associated with overall survival.

Conclusion.
In this study, we found no difference in ambulatory outcome for patients based on their race, SVI score, or insurance status. Likewise, no differences in postoperative survival were found. These findings suggest that despite differences in presentation or short-term outcome reported in other investigations, the social factors we explored were not associated with the likelihood of a patient being nonambulatory postoperatively or shorter survival after spinal tumor surgery. Research studies that analyze race as a covariate of interest should take care to explore metrics of socioeconomic deprivation (such as the SVI score) to avoid drawing misleading conclusions.

Level of Evidence
Level III, therapeutic study.