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Quality-of-life outcomes, cost utility of spinal stenosis surgery similar to THA, TKA
Patients who undergo surgery for one- or two-level focal lumbar spinal stenosis can expect to have a comparable long-term improvement in health-related quality of life to patients who underwent hip or knee arthroplasty for osteoarthritis, according to an investigator.
Raja Y. Rampersaud, MD, FRCSC, of Toronto Western Hospital in Canada, and colleagues conducted a two-part study to assess whether or not health-related quality of life at a minimum of five years after surgery for focal lumbar spinal stenosis was durable and sustainable compared with health-related quality of life after total hip arthroplasty (THA) and total knee arthroplasty (TKA). They also sought to determine the incremental cost utility of decompression and decompression with fusion vs. THA and TKA at a median of 5 years postsurgery.
“We all know that the burden of osteoarthritis individually and societally is quite tremendous,” Rampersaud said when he presented these results at a meeting. “Consistent outcomes have led to stable funding with regards to THA and TKA; however, due to inconsistent outcomes, as well as increasing demand, funding for implant-based spinal surgery in particular is certainly still under scrutiny.”
Raja Y.
Rampersaud
Part one – quality of life
The first part of the study, which was the Spine Journal Outstanding Paper in the Value category last year, was a single-center, retrospective longitudinal matched-cohort study. Data were collected prospectively on 99 consecutive patients with a diagnosis of spinal stenosis from 2000 to 2003. Of these patients, 71 underwent decompression alone and 28 underwent fusion. Thirty-eight patients had degenerative spondylolisthesis. Researchers matched these patients with age-, sex- and date-matched cohorts of 99 patients who underwent THA and 99 patients who underwent TKA.
Mean follow-up was almost 7 years for the spine surgery and TKA cohorts and 8 years for the THA cohort. Revision rates at follow-up were 20.2% for spine surgery, 3% for the THA cohort and 8.1% for the TKA cohort. “The revision rate for spine surgery was grossly higher than for THA and TKA, but 65% of the revision spine surgeries were actually for the adjacent segment,” Rampersaud said at the meeting.
A sagittal MRI demonstrating two-level
stenosis (L3-4 and L4-5) in a 65-year-old
female patient.
Image: Rampersaud RY
The mean change in SF-36 physical component summary (PCS) and mental component summary (MCS) scores was significant in all groups. “There was actually no difference in the mean end scores across the three groups,” Rampersaud said. “However, when we looked at degree of change for the PCS score, THAs were superior in change with 12 points of improvement vs. 8 points for spine and TKA, which were statistically and clinically not different whatsoever.”
Adjusted analyses still revealed the THA cohort had a strong trend for superiority, but the spine and TKA outcomes were nearly identical.
Cost utility focus of part two
In Part 2 of the study, the researchers performed a cost utility assessment of elective surgery relative to failed medical management from the perspective of the health care system only. Patients underwent surgery after a minimum 2 years of failed medical management; therefore, researchers used them as before and after control groups and assessed failed medical management by assuming it remained constant from baseline.
Researchers assessed cost utilities using the SF-6D at baseline, 2 years and 5 years. “Whether at the five-year mark or lifetime estimates, THAs certainly were dominant with regards to overall gain in quality-adjusted life years,” Rampersaud said. “When we looked at overall cost utility at the five-year mark, all interventions actually fell well below accepted thresholds for willingness to pay from a cost-per-quality-gained perspective.”
Over the lifetime, spinal decompression had the best cost utility, but when comparing decompression and fusion with THA and TKA, THA had more favorable cost utility.
“Sensitivity analyses adjusting the upper and lower limit of the utility outcome, the cost of intervention, revision rates, other drivers of cost, such as inpatient or outpatient rehabilitation, and our degree of discounting still showed that in the worst-case scenario, our costs per quality were still within the lowest ranges of the threshold,” Rampersaud said.
He and his colleagues concluded surgery for patients with lumbar spinal stenosis is associated with acceptable and similar cost utility to THA and TKA. “Certainly, this finding supports ongoing advocacy and improved and continued resource allocation for the treatment of spinal stenosis,” Rampersaud said. – by Tina DiMarcantonio
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Disclosure: Rampersaud is a consultant for Medtronic Spine and is a member of the scientific advisory board for Surgical Navigation Technologies.
Perspective
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Readers should spend a few extra minutes analyzing this important study and its relation to the methodology and application phases of Comparative Effectiveness Research (CER). CER has been adopted by the Federal Agency for Healthcare Research and Quality and many third-party payors to evaluate the effectiveness of and in some cases make decisions on reimbursement for various procedures. In the initial phase of CER, clinical outcomes are evaluated by outcomes instruments which reflect Health Related Quality of Life, e.g., SF-36/SF-6D, EuroQual 5D. Scores from these instruments are used to generate Utility Scores (reflecting general health status 0=death to 1=perfect health). The Utility Score (0-1) x years of sustained health improvement = improvement in Quality Adjusted Life Years (QALYs). Utility scores and QALYs are employed in advanced CER analyses such as Cost Utility and Cost Effectiveness. These CER calculations can be used not only to compare different spine procedures, but also show effectiveness vs. other surgeries (in this case joint arthroplasty) and also other interventions, such as renal dialysis.