Lifetime incremental cost–utility ratios for minimally invasive surgery for degenerative lumbar spondylolisthesis relative to failed medical management compared with total hip and knee arthroplasty for osteoarthritis

BACKGROUND: The objective of this study was to compare the cost-effectiveness of minimally invasive surgery (MIS) for patients with degenerative lumbar spondylolisthesis (DLS) relative to failed medical management with the cost-effectiveness of hip and knee arthroplasty for matched cohorts of patients with osteoarthritis. METHODS: A cohort of patients with DLS undergoing MIS procedures with decompression alone or decompression and instrumented fusion between 2008 and 2014 was matched to cohorts of patients with hip osteoarthritis (OA) and knee OA undergoing total joint replacement. Incremental cost–utility ratios (ICURs) were calculated from the perspective of the Ontario Ministry of Health, using prospectively collected Short Form–6 Dimension utility data. Costs and quality-adjusted life years (QALYs) were discounted at 3% and sensitivity analyses were performed. RESULTS: Sixty-six patients met the inclusion criteria for the DLS cohort (n = 35 for decompression alone), with a minimum follow-up time of 1 year (mean 1.7 yr). The mean age of patients in the DLS cohort was 64.76 years, and 45 patients (68.2%) were female. For each cohort, utility scores improved from baseline to follow-up and the magnitude of the gain did not differ by group. Lifetime ICURs comparing surgical with nonsurgical care were Can$7946/QALY, Can$7104/QALY and Can$5098/QALY for the DLS, knee OA and hip OA cohorts, respectively. Subgroup analysis yielded an increased ICUR for the patients with DLS who underwent decompression and fusion (Can$9870/QALY) compared with that for the patients with DLS who underwent decompression alone (Can$5045/QALY). The rank order of the ICURs by group did not change with deterministic or probabilistic sensitivity analyses. CONCLUSION: Lifetime ICURs for MIS procedures for DLS are similar to those for total joint replacement. Future research should adopt a societal perspective and potentially capture further economic benefits of MIS procedures.