Health Outcome Disparities After Treatment of Spinal Metastases: A Population-Based Cohort Study of Patients with High and Low Neighborhood-Level Material Deprivation

Introduction: Patient social marginalization can be quantified using a variety of metrics, including the neighborhood material deprivation index, a measure of poverty and access to basic material needs based on home address. In this study we compare patients with high and low material deprivation to assess the impact of social marginalization on survival and days at home after treatment of a spinal metastasis.

Methods: A population-based retrospective cohort study was conducted of patients treated with spinal metastases between 2007 to 2019 in Ontario, Canada. Patients were grouped into material deprivation quintiles from 1 (least deprived) to 5 (most deprived) using provincial census and taxation data. Propensity scores were used to match patients in the least deprived group to patients in the most deprived groups with covariate balance with respect to age, sex, rurality, baseline comorbidities, and primary cancer type. Survival was compared using a cox-proportional hazard model. We used provincial health data to compare the median number of days spent at home after treatment.

Results: We identified 35,896 patients treated for spinal metastases. Mean age was 64.0 years (13.0 SD), and most common primary cancers were lung (N = 9876, 28%), breast (N=5611, 16%), prostate (N=5409, 15%), and gastrointestinal (N=3083, 8.6%). There were 7080 (20%) patients in the lowest material deprivation quintile, and 7397 (21%) patients in the highest material deprivation quintile. We matched 7,080 patients with high deprivation to 7,080 patients with low deprivation, that were balanced with respect to other covariates (absolute standardized difference < 0.1 for all variables). Patient with high deprivation had significant worse survival (hazard ratio 1.11, 95% CI 1.08 – 1.16), and lower time at home (median difference -46.8 days, 95% CI -57.9 - -35.7 days).

Conclusion : This study presents real world data that highlights poverty and access related disparities in outcomes after treatment for spinal metastases.