Cost-effectiveness of ABM/P-15 versus Allograft in Degenerative Spondylolisthesis Surgery: 10-year Follow-up on a Randomized Controlled Trial.

Abstract

Randomized controlled trial. The aim of this study was to investigate whether ABM/P-15 was cost-effective compared to allograft as a bone graft extender for un-instrumented posterolateral fusion for degenerative spondylolisthesis with spinal stenosis in elderly patients. In an increasingly elderly population with higher expectations of good health and quality of life, the need for durable surgery with minor risks of implant-related reoperations is growing. Specifically for lumbar fusion surgery, the need for a reliable bone graft material with acceptable fusion rates and low graft-related morbidity and risk of reoperation is important. This cost-effectiveness analysis was based on a single-center, blinded, randomized controlled trial, where patients with symptomatic degenerative spondylolisthesis were randomly assigned 1:1 to either ABM/P-15 or Allograft as bone graft material in un-instrumented posterolateral fusion. Quality-Adjusted Life Years (QALY) were obtained from EQ-5D-3L. Use of health services were obtained from patient charts, costed and accumulated up to ten years after index surgery. The study included 101 patients with no inter-group differences in preoperative characteristics. Based on a bootstrapped analysis, the estimated the mean QALY gain for the ABM/P-15 group was 0.42 points (95% CI [-0.17; 1.08], P=0.185) greater compared to the Allograft group. Compared to the Allograft group, patients in the ABM/P-15 group had 20% less costs due to a significantly lower reoperation rate (18% vs 43%, P=0.024), fewer visits to the outpatient clinic, Magnetic Resonance Images and fewer days of hospitalization. The choice of bone graft material significantly affected cost-effectiveness of posterolateral lumbar fusion in elderly patients with degenerative spondylolisthesis at 10-year follow-up. ABM/P-15 showed dominance over Allograft with improved outcomes, lower healthcare costs and lower re-operation rate.