Value of single-level circumferential fusion: a 10-year prospective outcomes and cost-effectiveness analysis comparing posterior facet versus pedicle screw fixation.

Abstract

To compare the clinical and economic outcomes of facet versus pedicle screw instrumentation for single-level circumferential lumbar spinal fusion. Outcomes included self-assessment of back and leg pain, pain drawing, ODI, pain medication usage, and procedure success. The CEA was based on the 10-year data collected, and the base-case was from a US payer perspective. Costs included the index surgery, additional surgeries, outpatient/ED visits, and medications. To determine quality-adjusted life years (QALYs), ODI scores were used to predict SF-6D utilities. Sensitivity analyses were performed from a modified payer perspective including device costs and from a societal perspective including productivity loss. Discounted and undiscounted incremental costs and QALYs were calculated. Bootstrapping was performed to estimate the distribution of incremental costs and effects. Clinical improvement was significant from pre-op to 10-year follow-up for both groups (p < 0.01 for all outcomes scales). Outcomes were significantly better for back pain and ODI for the facet versus pedicle group at all follow-up periods > 1year (p < 0.05). In the CEA base-case, facets had more QALYs (0.68) and lower costs (- $8650) per person compared with pedicle screws. Therefore, facets were dominant (i.e., provided costsavings and greater QALYs) compared with pedicle screws. Facets had a 97% probability of being below a willingness-to-pay threshold of $20,000 per QALY gained and were estimated to be dominant over pedicle screws in 84% of the simulations. One-level circumferential spinal fusion using facet screws was clinically superior and provided cost savings compared with pedicle screw instrumentation in the USA.