Surgical treatment of spinal stenosis with and without degenerative spondylolisthesis: cost-effectiveness after 2 years

Abstract

Background: The SPORT (Spine Patient Outcomes Research Trial) reported favorable surgery outcomes over 2 years among patients with stenosis with and without degenerative spondylolisthesis, but the economic value of these surgeries is uncertain.

Objective: To assess the short-term cost-effectiveness of spine surgery relative to nonoperative care for stenosis alone and for stenosis with spondylolisthesis.

Design: Prospective cohort study.

Data sources: Resource utilization, productivity, and EuroQol EQ-5D score measured at 6 weeks and at 3, 6, 12, and 24 months after treatment among SPORT participants.

Target population: Patients with image-confirmed spinal stenosis, with and without degenerative spondylolisthesis.

Time horizon: 2 years.

Perspective: Societal.

Intervention: Nonoperative care or surgery (primarily decompressive laminectomy for stenosis and decompressive laminectomy with fusion for stenosis associated with degenerative spondylolisthesis).

Outcome measures: Cost per quality-adjusted life-year (QALY) gained.

Results of base-case analysis: Among 634 patients with stenosis, 394 (62%) had surgery, most often decompressive laminectomy (320 of 394 [81%]). Stenosis surgeries improved health to a greater extent than nonoperative care (QALY gain, 0.17 [95% CI, 0.12 to 0.22]) at a cost of $77,600 (CI, $49,600 to $120,000) per QALY gained. Among 601 patients with degenerative spondylolisthesis, 368 (61%) had surgery, most including fusion (344 of 368 [93%]) and most with instrumentation (269 of 344 [78%]). Degenerative spondylolisthesis surgeries significantly improved health versus nonoperative care (QALY gain, 0.23 [CI, 0.19 to 0.27]), at a cost of $115,600 (CI, $90,800 to $144,900) per QALY gained. RESULT OF SENSITIVITY ANALYSIS: Surgery cost markedly affected the value of surgery.

Limitation: The study used self-reported utilization data, 2-year time horizon, and as-treated analysis to address treatment nonadherence among randomly assigned participants.

Conclusion: The economic value of spinal stenosis surgery at 2 years compares favorably with many health interventions. Degenerative spondylolisthesis surgery is not highly cost-effective over 2 years but could show value over a longer time horizon.

Figure 1. Adjusted mean EuroQol EQ-5D health state values and 95% CIs over time, by treatment received

Top. Spinal stenosis group. Bottom. Degenerative spondylolisthesis with spinal stenosis group.

Figure 2. Cost-effectiveness acceptability curves, by disease group and analytic assumption

The primary analysis used total costs based on Medicare payment amounts and the EuroQol EQ-5D to estimate QALYs. The SF-6D analyses estimated QALYs based on this form. Higher surgery costs were based on 70% of the amount billed to Medicare. DS = degenerative spondylolisthesis; QALY = quality-adjusted life-year; SF-6D = Short Form-6D; SpS = spinal stenosis.