Cost-Effectiveness of Instrumented Versus Uninstrumented Posterolateral Fusion for Single-level Degenerative Spondylolisthesis

Study Design. Randomized controlled trial. Objective. The aim of this study was to investigate whether instrumented posterolateral fusion is cost-effective compared with uninstrumented posterolateral fusion in elderly patients who undergo fusion surgery for one-level degenerative spondylolisthesis with spinal stenosis. Summary of Background Data. For patients with persistent symptoms due to degenerative spondylolisthesis, surgical intervention may be recommended, typically decompression and fusion. Evidence on cost-effectiveness of choice of fusion method, related complications, and outcome is sparse. Methods. This cost-effectiveness analysis is based on a single-center, open-label, randomized controlled trial, where patients with symptomatic degenerative spondylolisthesis were randomly assigned 1:1 to either instrumented or un-instrumented posterolateral fusion. Quality-Adjusted Life Years were obtained from EQ-5D. Use of health services was obtained from patient charts and accumulated until 2 years after index surgery. Results. Of the 108 patients included in the study, 107 patients received the allocated intervention. There were no differences in preoperative demographics. Although the base price for the index instrumented surgery was significantly higher than the index uninstrumented surgery, average cost of surgery was only €146 higher in the instrumented group based on two-year cost data. The instrumented fusion group had a significantly lower reoperation rate [1/54 (1.9%)] than the uninstrumented fusion group 7/53 (13.2%), significantly less visits to the outpatient clinic, less magnetic resonance imaging performed and fewer days of hospitalization. The base case incremental cost-effectiveness ratio was estimated at €1536 per QALY gained over a two-year time horizon. Instrumented fusion was favored over uninstrumented fusion in sensitivity analyses including all reoperations or using hospital reimbursement rate. Conclusion. Instrumented fusion is cost-effective compared uninstrumented fusion, with an incremental cost-effectiveness ration well below the standard range of cost-effectivenes, the difference in cost was driven by lower reoperation rates and less health care resource utilization over a two-year time horizon.