Days at home after treatment of spinal metastases: measurement and validation of a novel patient centered outcome

Purpose Clinically meaningful population health outcomes for patients with spinal metastases are lacking. This study quantifies and validates days at home (DAH) after treatment of spinal metastases, and investigates factors associated with this patient-centered outcome. Methods A population-based cohort study was conducted with the 2007-2019 Ontario Cancer Registry. Patients aged over 18 years undergoing surgery and/or radiation for a spinal metastasis were included. DAH was assessed at 3 months, 6 months (DAH-180), 1 year (DAH-365), and 2 years (DAH-730) after first treatment. Associations between DAH and primary cancer type, age, and frailty were assessed using multivariable quantile regression to estimate adjusted medians differences (aMD) in DAH. Predictive validity was determined with Spearman correlations between DAH-180 and longer-term DAH measures. Results We identified 36,233 treated patients. Median DAH for patients after 3 months, 6 months, 1 year, and 2 years from treatment were 79 days, 114 days, 120 days, and 121 days, respectively. Lower home time was associated with older age (aMD: -16 days per decade increase in age), and frailty (aMD: -36). Primary cancers associated with the least DAH included gastrointestinal cancer (aMD: -162 days), lung cancer (aMD: -165 days), and melanoma (aMD: -167 days). DAH-180 demonstrated predictive validity with longer term DAH-365 (p < 0.001), and DAH-730 (p < 0.001). Conclusion These data help validate DAH as a reliable metric for patients treated for spinal metastases. Patients with older age, frailty, high health resource utilization, and primary melanoma, gastrointestinal or lung cancer were found to have the fewest DAH after treatment.