Cost per quality-adjusted life year gained of laminectomy and extension of instrumented fusion for adjacent-segment disease: defining the value of surgical intervention

Abstract

Object: Over the past decade, there has been a dramatic increase in the number of spinal fusions performed in the US and a corresponding increase in the incidence of adjacent-segment disease (ASD). Surgical management of symptomatic ASD consists of decompression of neural elements and extension of fusion. It has been shown to have favorable long-term outcomes, but the cost-effectiveness remains unclear. In this study, the authors set out to assess the cost-effectiveness of revision surgery in the treatment of ASD over a 2-year period.

Methods: Fifty patients undergoing neural decompression and extension of fusion construct for ASD-associated back and leg pain were included in the study. Two-year total back-related medical resource utilization, missed work, and health state values (quality-adjusted life years [QALYs], calculated from the EQ-5D with US valuation) were assessed. Two-year resource use was multiplied by unit costs based on Medicare national allowable payment amounts (direct cost), and patient and caregiver workday losses were multiplied by the self-reported gross-of-tax wage rate (indirect cost). Mean total 2-year cost per QALY gained after revision surgery was assessed.

Results: The mean (± SD) interval between prior fusion and revision surgery for ASD was 3.07 ± 2.02 years. A mean cumulative 2-year gain of 0.76 QALYs was observed after revision surgery. The mean total 2-year cost of extension of fusion constructs was $47,846 ± $32,712 (surgery cost: $24,063 ± $300; outpatient resource utilization cost: $4175 ± $3368; indirect cost: $19,607 ± $32,187). Revision decompression and extension of fusion was associated with a mean 2-year cost per QALY gained of $62,955.

Conclusions: In the authors' practice, revision decompression and extension of fusion provided a significant gain in health state utility for patients with symptomatic ASD, with a 2-year cost per QALY gained of $62,995. When indicated, revision surgery for ASD is a valuable treatment option for patients experiencing back and leg pain secondary to ASD. The findings provide a value measure of surgery that can be compared with future cost-per-QALY-gained studies of medical management or alternative surgical approaches.