Non-operative management of spinal metastases: A prognostic model for failure

To describe patient-specific characteristics associated with non-operative failure leading to surgery.

We conducted a retrospective review of patients treated for spinal metastases from 2005 to 2017. We deemed patients as failures if they were treated non-operatively and then received a surgical intervention within one year of starting a non-operative regimen. We used multivariable Poisson regression to identify factors associated with non-operative failure. We conducted internal validation using bootstrapping with 1000 replications.

We identified 1205 patients with spinal metastases, of whom 834 were initially treated non-operatively and constituted the analytic sample. Of these 77 (9%) went on to have surgery within 1-year of presentation and were deemed non-operative treatment failures. We identified vertebral body collapse and/or pathologic fracture (adjusted Risk Ratio [RR] 1.75; 95% Confidence Interval [CI] 1.11, 2.76) and neurologic signs or symptoms at presentation (RR 1.90; 95% CI 1.19, 3.03) as factors independently associated with an increased risk of non-operative failure. Platelet-lymphocyte ratio >155, a marker for inflammatory state, was also associated with an increased risk of failure (RR 2.32; 95% CI 1.15, 4.69). Failure rates among those with 0, 1, 2 or all three of these risk factors were 5%, 7%, 12% and 20%, respectively (p = 0.004).

We found that 9% of patients with spinal metastases initially treated non-operatively received surgery within 1-year of commencing care. The likelihood of surgery increased with the number of risk factors. These results can be used in counseling and shared decision making at the time of initial presentation.