Socioeconomic status and outcomes following spine stereotactic body radiation therapy

The Area Deprivation Index (ADI) ranks neighborhoods by adverse social exposome, considering factors related to income, education, employment, and housing quality. This study evaluates the association between socioeconomic status and outcomes following spine stereotactic body radiation therapy (SBRT).

A prospectively maintained database of consecutive patients treated with spine SBRT at a quaternary referral center from 2001 to 2024 was analyzed. Patient addresses were matched to the 2020 ADI to define most advantaged (ADI ≤ 50, 140 patients, 227 metastases) and least advantaged (ADI > 50, 357 patients, 553 metastases) cohorts.

The distribution of race and ethnicity differed between cohorts, with a greater proportion of Black or African American patients in the least advantaged cohort (2% vs. 6%, P = 0.008). Public insurance coverage was more common in the least advantaged cohort (42% vs. 54%, P = 0.020). There were no differences with respect to age (P = 0.904), sex (P = 0.495), Karnofsky Performance Status (P = 0.930), radioresistant histologies (P = 0.626), systemic disease burden (P = 0.127), prior or adjuvant chemotherapy (P = 0.146) or immunotherapy (P = 0.537), prior open surgical resection (P = 0.196) or conventional external beam radiation therapy (P = 0.268), Bilsky grade (P = 0.191), Spinal Instability Neoplastic Score (P = 0.076), gross tumor volume (P = 0.731), fractionation regimen (P = 0.437), or biologically effective dose (P = 0.499). There was no difference in 6-month, 1-year, 2-year, and 3-year local control (96%, 88%, 85%, and 79% vs. 91%, 83%, 76%, and 73%; P = 0.062) or overall survival (72%, 56%, 37%, and 28% vs. 70%, 55%, 36%, and 28%; P = 0.890). There was no difference in complete or partial pain response (44% vs. 41%, P = 0.196), radiation toxicity (12% vs. 12%, P = 0.876), or vertebral compression fractures (11% vs. 10%, P = 0.637) following treatment. Multivariable Cox proportional hazards analyses did not identify race or ethnicity, insurance coverage, or the ADI as predictors of local control or overall survival.

Race or ethnicity, insurance coverage, and neighborhood deprivation were not associated with any measured outcomes following spine SBRT. These findings suggest equitable SBRT delivery once patients access care at an academic referral center and reinforce the need to improve referral pathways and insurance authorization for socioeconomically disadvantaged patients.