Low back and leg pain secondary to degeneration of the lumbar spine (spondylolisthesis) is occurring with increasing frequency, concurrent with the rising population of people age 65 and older living in the US. As a result, there has been a marked increase in the rate of spinal fusion operations and corresponding healthcare costs over the past two decades. Spinal fusion is an operation that creates a solid union between two or more vertebrae. This procedure may assist in strengthening and stabilizing the spine and may thereby help to alleviate severe and chronic back and leg pain. "Although it is clear that healthcare costs associated with spinal fusion procedures have increased, the cost effectiveness of transforaminal lumbar interbody fusion (TLIF) has not been elucidated conclusively in prior studies," stated co-presenting authors Matthew J. McGirt, MD, and Scott L. Parker, BS.

Researchers at Vanderbilt University Medical Center in Nashville, Tenn. set out to assess the cost-effectiveness of TLIF, a single lumbar fusion surgical technique commonly used to stabilize the vertebrae of the spine and disc between the vertebrae, with the goal of reducing pain from nerve irritation. The results of this study, Cost Effectiveness of Transforaminal Lumbar Inter-Body Fusion (TLIF) for Grade I Degenerative Spondylolisthesis, will be presented by Dr. McGirt and Mr. Parker, 11:45-11:59 am, Tuesday, April 12, during the 79th Annual Scientific Meeting of the American Association of Neurological Surgeons in Denver. Co-authors are Owoicho Adogwa, MPH, Alexandra Paul, MD, Brandon Davis, MD, PhD, Oran Aaronson, MD, Clint Devon, MD, and Joseph Cheng, MD.

Patient Inclusion Criteria

- MRI evidence of grade I degenerative lumbar spondylolisthesis
- Mechanical low-back pain and radicular symptoms
- Failed at least 6 months of conservative therapy
- Ages 18 to 70

Patient Exclusion Criteria

- History of a previous back operation
- Extra-spinal cause of back pain or sciatica
- Active medical or workman's compensation lawsuit
- Pre-existing spinal pathology of any kind
- Unwilling or unable to participate with follow-up procedures
- Notable associated abnormalities; such as inflammatory arthritis, or metabolic bone

Pain, disability, and overall health were assessed preoperatively and two years postoperatively utilizing outcome questionnaires completed either during clinic evaluation or via phone interview. Patient-assessed questionnaires included an 11 point (0-10) Visual Analogue Scale (VAS) for low back pain and leg pain; Oswestry Disability Index (ODI) disability questionnaire; and EuroQol-5D (EQ-5D) quality of life questionnaire. The EQ-5D questionnaire was used to calculate the quality adjusted life years (QALY) associated with TLIF. QALY is a measure of disease burden and includes both the quality of life and the quantity of life lived. When combined with cost data, it can be used to assess the value of a medical intervention.

Medical resource utilization was assessed over a two-year period postsurgery. Direct costs consisted of doctor visits, diagnostic tests, emergency room visits, medications, and physical therapy. The indirect costs were estimated by assessing the productivity losses due to spine-related problems such as missed workdays for those employed outside the home. The following outcome and cost effectiveness results were noted:

- All two-year patient-assessed outcomes assessed were significantly improved from preoperative levels. Two years postsurgery, the mean change in back pain and leg pain from baseline was 4.3 and 3.8 points, respectively.

- Patients reported significantly less disability and improved quality of life as assessed by the questionnaires. The cumulative health utility value gained over a two-year interval after TLIF was 0.86 QALY.

- Mean two-year direct medical cost of TLIF was $25,251.

- Mean surgical cost was $21,311 +/- 2086 and mean outpatient resource cost was $3940 +/- 2720.

Median reported annual income prior to surgery was $50,000. There was a median of 60 missed work days. This represents a mean two-year indirect societal cost of $11,584.

- The mean total two-year cost of TLIF was $36,835 +/- 11,800.

- At two years postsurgery, the total cost per QALY gained of TLIF was $42,854.

"The cost per QALY gained is under the well accepted $50,000 cost-effective threshold, suggesting that TLIF is a cost-effective treatment option for patients with back and leg pain associated with grade 1 degenerative spondylolisthesis," said Mr. Parker. "TLIF for patients primarily with back pain and minimal leg pain may be less cost-effective. Patient selection and surgical indication correlates closely with the procedure's efficacy and cost effectiveness and should be considered carefully," concluded Dr. McGirt.

Source:
American Association of Neurological Surgeons (AANS)