A study to determine the cost-effectiveness of single-level instrumented posterolateral lumbar fusion at 5 years after surgery found that the procedure falls within an acceptable range both for benefit versus cost and for durability.

The study, presented by Steven D. Glassman, MD, at the AAOS 2010 Annual Meeting, is one of the first to examine this issue at the 5-year postoperative interval. At that point, the direct cost per quality-adjusted life year (QALY) gained was approximately $33,000; when the total work productivity cost was factored in, the direct cost per QALY gained was $54,000 (Table 1). Cost analysis was based on actual reimbursements from third-party payors, including payments for the index procedure, treatment of complications, emergency department outpatient visits, and revision surgery. An analysis was also made based on Medicare reimbursement, yielding a direct cost per QALY gained of $30,000 ($51,000 with indirect costs included).

Cost per QALY gained is the most widely accepted measurement among healthcare economists and policy makers for comparing the value of competing healthcare interventions because it is generic and can be used across medical treatments. Although specific thresholds are controversial, the authors note that interventions with a cost per QALY gained of up to $100,000 are generally considered cost-effective.

For the study, 96 patients were enrolled at a single site that was part of a Food and Drug Administration trial evaluating recombinant human bone morphogenetic protein–2 (rhBMP-2) and a compression-resistant matrix product. Patients had symptomatic, single-level lumbar degenerative disease (L2-L3 to L5-S1) of at least 6 months’ duration, and nonsurgical care had failed to resolve pain. Data on clinical outcomes postoperatively were collected four times during the first year and annually thereafter.

To determine QALYs, the SF-6D instrument, a utility index derived from the Short Form 36 (SF-36) questionnaire, was used. Medical and surgical treatments within the 6-month postoperative window were attributed to the surgical procedure.

Complete data for the 5-year period were available for 80 patients, who had a mean age of 52 years. Health-related quality of life scores improved in all measures at all time points compared with the baseline. The biggest improvements occurred at 6 months for back and leg pain, at 12 months for the Oswestry Disability Index, and at 24 months for the Physical Component Summary of the SF-36. The mean SF-6D health utility value gained in each of the 5 years was 0.12, 0.14, 0.13, 0.15, and 0.15, for a total 0.69 QALY improvement over the full interval.

Mean actual reimbursement for the index procedure was $17,092 (± $7,705); Medicare mean reimbursement was $15,720 (± $2,962). There were 11 revision surgeries, with a mean actual reimbursement of $29,402 (± $9,362). Mean actual reimbursement for 5 years after surgery was $22,708 (± $12,788).

At the 5-year follow-up, 12 of the 57 patients who had not been working prior to surgery had returned to work, and 12 of the 23 patients who had been working prior to surgery also returned to work. The 48 patients not working after surgery were significantly older than those who returned to work (55.0 vs. 47.6 years; p = 0.003).

Dr. Glassman noted that limitations of the study include loss to follow-up of 17 percent of the initial cohort and the lack of a control group, with the resultant inability to report an incremental cost-effectiveness ratio. Even with these limitations, the authors wrote, the study represents one of the first available reports of cost-effectiveness for lumbar fusion based on directly measured parameters at 5 years postoperatively.

Co-authors of “The Cost Effectiveness of Lumbar Fusion at Five Years after Surgery” are David W. Polly Jr., MD; John R. Dimar II, MD; and Leah Y. Carreon, MD, MSc.

Dr. Glassman reports ties to Medtronic Sofamor Danek and DePuy.

Terry Stanton is senior science writer for AAOS Now. He can be reached at tstanton@aaos.org

Bottom line

• Direct costs for single level lumbar fusion range from $30,000 (Medicare reimbursement) to $33,000 (private payors) per quality-adjusted life year.
• Health-related quality of life scores improved in all measures at all time points compared with the baseline.