Cost-Effectiveness of Treatment Strategies for Spinal Metastases

We analyzed the cost-effectiveness of standard palliative external beam radiation (EBRT, 8 Gy in 1 fraction), stereotactic body radiation therapy (SBRT, 24 Gy in 2 fractions), and radiofrequency ablation for painful spinal metastases. Single-fraction SBRT (delivering 24 Gy) was also assessed.

A Markov state transition model was constructed. Key model parameters were derived from prospective clinical trial data. Strategies were compared using the incremental cost-effectiveness ratio (ICER), with effectiveness in quality-adjusted life-years (QALYs) and a willingness-to-pay threshold of $100,000 per QALY gained. Costs included both hospital and professional costs using 2020 Medicare reimbursement.

The base case demonstrated that 2-fraction SBRT was not cost-effective compared with single-fraction EBRT, with an ICER of $194,145 per QALY gained. Radiofrequency ablation was a more costly and less effective strategy in this model. Probabilistic sensitivity analysis demonstrated that EBRT was favored in 66% of model iterations. If median survival were improved after SBRT, 2-fraction SBRT became cost-effective, with ICERs of $80,394, $57,062, and $47,038 for 3-, 6-, and 9-month improvements in survival, respectively. Because 2-fraction SBRT data reported that 18% of patients had an indeterminant pain response at 3 months and 2-fraction SBRT is infrequently used in clinical practice, single-fraction SBRT data were also assessed. Single-fraction SBRT delivering 24 Gy was cost-effective compared with single-fraction EBRT, with an ICER of $92,833 per QALY gained.

For appropriately chosen patients, single-fraction SBRT was more cost-effective than conventional EBRT or radiofrequency ablation. Conventional EBRT remains a cost-effective treatment for patients with poor expected survival.