title: Factors Predicting Cost-effectiveness of Adult Spinal Deformity Surgery at 2 Years.
abstract: OBJECTIVE
  To identify preoperative factors that lead to cost-effectiveness at 2 years' follow-up in the setting of surgical treatment for adult spinal deformity.
  
  
  METHODS
  Retrospective analysis of a prospective, consecutive, multicenter database including 514 patients who underwent surgery for adult spinal deformity. The change in quality-adjusted life-years (QALY) was calculated from the 2-year change in Oswestry Disability Index (ODI). Medicare coding was used to determine the direct costs based on diagnosis-related group and Relative Value Unit reimbursement. Analysis was performed to determine which factors were associated with a cost/QALY less than $100,000, making the procedure cost-effective.
  
  
  RESULTS
  The average QALY change for all patients in this study was 0.15 and the average cost/QALY was $243,761.97. A total of 56 patients (10.4%) had a cost/QALY of less than $100,000 at 2-year follow-up. Those patients were mostly female (89%), with a mean age of 60 years and the following diagnoses: 18 (32.1%) adult idiopathic scoliosis, 12 (35.7%) adult de novo scoliosis, 87 (14.3%) sagittal imbalance, and 10 (17.9%) other scoliosis. The Health-Related Quality of Life ODI and Scoliosis Research Society (SRS) instruments were all associated with cost-effectiveness except SRS-Mental. Factors associated with cost-effectiveness were age greater than 55 years, adult de novo scoliosis, prior surgery, higher preoperative sagittal vertical axis, lower maximum Cobb angles, 8 or fewer fusion levels, lower blood loss, worse global alignment classification, and global sagittal malalignment. Combined anterior-posterior surgeries were negatively associated with cost-effectiveness. Preoperative ODI scores between 60 and 70 and SRS Pain and Activity subscores more than 4 minimally clinically important difference points below the normative values had the highest percentage of cost-effective patients.
  
  
  CONCLUSIONS
  The QALY change is 0.15 and the cost/QALY of adult deformity surgery is $243,761.97 at 2 years. Patients with higher preoperative morbidity are more likely to be cost-effective with a cost/QALY less than $100,000.
authors.affiliation: Department of Orthopaedic Surgery, Columbia University Medical Center, 622 West 168th Street, PH 11-1130, New York, NY, 10032, USA; Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, 301 East 17th Street, New York, NY 10003, USA. Electronic address: charla.fischer@gmail.com.
authors.forename: Charla R
authors.initials: CR
authors.lastname: Fischer
authors.affiliation: Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, 301 East 17th Street, New York, NY 10003, USA.
authors.forename: Jamie
authors.initials: J
authors.lastname: Terran
authors.affiliation: Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, 301 East 17th Street, New York, NY 10003, USA.
authors.forename: Baron
authors.initials: B
authors.lastname: Lonner
authors.affiliation: Department of Neurosurgery, Yale University, P.O. Box 208082, New Haven, CT 06520-8082, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: McHugh
authors.affiliation: Department of Neurosurgery, Vancouver Island Health Authority, 1952 Bay Street, Victoria, British Columbia, Canada.
authors.forename: Dan
authors.initials: D
authors.lastname: Warren
authors.affiliation: Department of Orthopaedics, Norton Leatherman Spine Center, 210 E Gray St, Louisville, KY.
authors.forename: Steven
authors.initials: S
authors.lastname: Glassman
authors.affiliation: Department of Orthopaedics, Washington University in St. Louis, 660 S. Euclid Ave, Campus Box 8233, St. Louis, MO 63110, USA.
authors.forename: Keith
authors.initials: K
authors.lastname: Bridwell
authors.affiliation: Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, 301 East 17th Street, New York, NY 10003, USA.
authors.forename: Frank
authors.initials: F
authors.lastname: Schwab
authors.affiliation: Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, 301 East 17th Street, New York, NY 10003, USA.
authors.forename: Virginie
authors.initials: V
authors.lastname: Lafage
keywords: Adult spinal deformity; Cost-effectiveness; QALY; Spinal fusion