An open question in orthopedic oncology is whether patients with spinal metastases should be treated surgically. Currently, nonoperative care is the norm, particularly for patients whose neurologic function is intact. However, several studies suggest surgery helps preserve ambulatory function, and the cost might be offset by improvements in pain and functional independence.
Andrew J. Schoenfeld, MD, orthopedic surgeon in the Department of Orthopaedic Surgery at Brigham and Women’s Hospital, Elena Losina, PhD, co-director of the Brigham’s Orthopaedic and Arthritis Center for Outcomes Research and a founding director of the Policy and Innovation eValuation in Orthopaedic Treatments Center, and colleagues conducted the first cost-effectiveness analysis of surgery for spinal metastases that accounts for ambulatory function at presentation.
In the Journal of Bone & Joint Surgery, they say cost-effectiveness from society’s point of view does depend on the degree of ambulatory status at presentation, as well as the effectiveness of treatment in maintaining or restoring functional independence.
Overview of the Model
The researchers used a Markov model, which can compute the relative cost of an intervention based on changes over time in hypothetical patients. In this study, the patients were assumed to have metastatic epidural canal compromise at T12 and L1 from a radiosensitive tumor. One cohort was independent at presentation and the other was nonambulatory due to acute (<48 hours) metastatic epidural compression.
In a Markov model, simulated transitions between health statuses occur at a fixed time interval. In this study, the transitions (from independent to dependent on a mobility device to nonambulatory to death) occurred every 30 days based on ambulatory state, treatment received (operative or nonoperative) and postoperative events. The status sometimes did not change, and sometimes it improved.
Variables were based on existing medical literature and costs were based on 2019 Medicare data.
The model outputs were quality-adjusted life years (QALY)—a measure of how an intervention or non-intervention affects survival and quality of life—and lifetime direct medical costs.
The researchers calculated the incremental cost-effectiveness ratio (ICER), the difference in costs divided by the difference in QALYs between the operative and nonoperative strategies. The ICER represents the value of resources spent against the maximal cost society is willing to spend for each additional QALY gained.
As in many other U.S. cost-effectiveness studies, the willingness-to-pay thresholds used were $100,000 and $150,000. If the ICER of treatment was below the threshold, the treatment was considered cost-effective.
Results for Independent Ambulators
From the health care sector perspective, surgery was not cost-effective for patients who had independent ambulatory status at presentation:
- QALYs—0.823 for patients who underwent surgery and 0.800 for those treated nonoperatively
- Costs—$73,777 and $53,299
- ICER for operative vs. nonoperative management—$899,700 per QALY
Results for Nonambulatory Patients
Surgical intervention provided good value for patients who were nonambulatory at presentation due to acute neurologic compromise:
- QALYs—0.813 for patients who underwent surgery and 0.089 for those treated nonoperatively
- Costs—$73,481 and $38,330
- ICER for operative vs. nonoperative management—$48,600 per QALY
Guidance for Physicians
In general, radiation and observation will usually be more appropriate than surgery for patients with spinal metastatic disease who are independent ambulators, and surgery can be considered for those with acute neurologic deficit.
However, these results are not intended as treatment guidelines. Even the cost-effectiveness of surgery and anticipated dramatic improvement in quality of life must be weighed against remaining life expectancy. No one-size-fits-all strategy can balance health care policy goals with individual patient priorities.