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

PURPOSE: To compare the clinical and economic outcomes of facet versus pedicle screw instrumentation for single-level circumferential lumbar spinal fusion. METHODS: 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. RESULTS: 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 > 1 year (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 cost savings 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. CONCLUSION: One-level circumferential spinal fusion using facet screws was clinically superior and provided cost savings compared with pedicle screw instrumentation in the USA.