Cost-Effectiveness of ABM/P-15 Versus Allograft in Degenerative Spondylolisthesis Surgery : Ten-Year Follow-Up on a Randomized Controlled Trial

Randomized controlled trial. The aim of this study was to investigate whether ABM/P-15 was cost-effective compared with allograft as a bone graft extender for uninstrumented 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 uninstrumented posterolateral fusion. Quality-adjusted life years (QALY) were obtained from EQ-5D-3L. Use of health services was obtained from patient charts, costed and accumulated up to 10 years after index surgery. The study included 101 patients with no inter-group differences in preoperative characteristics. On the basis of 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 with the Allograft group. Compared with 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 health care costs, and lower reoperation rate.