title: Modeled cost-effectiveness of transforaminal lumbar interbody fusion compared with posterolateral fusion for spondylolisthesis using N(2)QOD data.
abstract: OBJECTIVE Transforaminal lumbar interbody fusion (TLIF) has become the most commonly used fusion technique for lumbar degenerative disorders. This suggests an expectation of better clinical outcomes with this technique, but this has not been validated consistently. How surgical variables and choice of health utility measures drive the cost-effectiveness of TLIF relative to posterolateral fusion (PSF) has not been established. The authors used health utility values derived from Short Form-6D (SF-6D) and EQ-5D and different cost-effectiveness thresholds to evaluate the relative cost-effectiveness of TLIF compared with PSF. METHODS From the National Neurosurgery Quality and Outcomes Database (N(2)QOD), 101 patients with spondylolisthesis who underwent PSF were propensity matched to patients who underwent TLIF. Health-related quality of life measures and perioperative parameters were compared. Because health utility values derived from the SF-6D and EQ-5D questionnaires have been shown to vary in patients with low-back pain, quality-adjusted life years (QALYs) were derived from both measures. On the basis of these matched cases, a sensitivity analysis for the relative cost per QALY of TLIF versus PSF was performed in a series of cost-assumption models. RESULTS Operative time, blood loss, hospital stay, and 30-day and 90-day readmission rates were similar for the TLIF and PSF groups. Both TLIF and PSF significantly improved back and leg pain, Oswestry Disability Index (ODI) scores, and EQ-5D and SF-6D scores at 3 and 12 months postoperatively. At 12 months postoperatively, patients who had undergone TLIF had greater improvements in mean ODI scores (30.4 vs 21.1, p = 0.001) and mean SF-6D scores (0.16 vs 0.11, p = 0.001) but similar improvements in mean EQ-5D scores (0.25 vs 0.22, p = 0.415) as patients treated with PSF. At a cost per QALY threshold of $100,000 and using SF-6D-based QALYs, the authors found that TLIF would be cost-prohibitive compared with PSF at a surgical cost of $4830 above that of PSF. However, with EQ-5D-based QALYs, TLIF would become cost-prohibitive at an increased surgical cost of $2960 relative to that of PSF. With the 2014 US per capita gross domestic product of $53,042 as a more stringent cost-effectiveness threshold, TLIF would become cost-prohibitive at surgical costs $2562 above that of PSF with SF-6D-based QALYs or at a surgical cost exceeding that of PSF by $1570 with EQ-5D-derived QALYs. CONCLUSIONS As with all cost-effectiveness studies, cost per QALY depended on the measure of health utility selected, durability of the intervention, readmission rates, and the accuracy of the cost assumptions.
authors.affiliation: Norton Leatherman Spine Center, Louisville, Kentucky;
authors.forename: Leah Y
authors.initials: LY
authors.lastname: Carreon
authors.affiliation: Norton Leatherman Spine Center, Louisville, Kentucky;
authors.forename: Steven D
authors.initials: SD
authors.lastname: Glassman
authors.affiliation: Alan and Jacqueline Stuart Spine Center, Department of Neurosurgery, Lahey Hospital and Medical Center, Burlington, Massachusetts;
authors.forename: Zoher
authors.initials: Z
authors.lastname: Ghogawala
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco, California; and.
authors.forename: Praveen V
authors.initials: PV
authors.lastname: Mummaneni
authors.affiliation: Carolina Neurosurgery & Spine Associates, Charlotte, North Carolina.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: McGirt
authors.affiliation: Carolina Neurosurgery & Spine Associates, Charlotte, North Carolina.
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Asher
mesh_terms: D000368:Aged; D001416:Back Pain / Q000453:epidemiology / Q000209:etiology / Q000601:surgery; D016063:Blood Loss, Surgical; D003362:Cost-Benefit Analysis / Q000379:methods; D004185:Disability Evaluation; D005260:Female; D017048:Health Care Costs; D006801:Humans; D007902:Length of Stay; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D018803:Models, Economic; D010359:Patient Readmission; D012042:Registries; D013123:Spinal Fusion / Q000191:economics* / Q000379:methods*; D013168:Spondylolisthesis / Q000150:complications / Q000453:epidemiology / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome
keywords: EQ-5D; N2QOD = National Neurosurgery Quality and Outcomes Database; ODI = Oswestry Disability Index; PSF = posterolateral fusion; QALY = quality-adjusted life year; SF-6D; TLIF = transforaminal lumbar interbody fusion; cost-effectiveness; posterolateral fusion; spinal disorders; transforaminal lumbar interbody fusion