title: Impact of cost valuation on cost-effectiveness in adult spine deformity surgery.
abstract: Over the past decade, the number of adult spinal deformity (ASD) surgeries has more than doubled in the United States. The complex surgeries needed to manage ASD are associated with significant resource utilization and high cost, making them a primary target for increased scrutiny. Accordingly, it is important to not only demonstrate value in ASD surgery as clinical effectiveness but also to translate outcome assessment to cost-effectiveness.
  
  
  
  To compare the difference between Medicare allowable rates and the actual, direct hospital costs for ASD surgeries.
  
  
  
  Longitudinal cohort.
  
  
  
  Consecutive patients enrolled in an ASD database from a single institution.
  
  
  
  Short Form (SF)-6D.
  
  
  
  Consecutive patients enrolled in an ASD database from a single institution from 2008 to 2013 were identified. Direct hospital costs were collected from hospital administrative records for the entire inpatient episode of surgical care. Medicare allowable rates were calculated for the same inpatient stays using the year-appropriate Center for Medicare-Medicaid Services Inpatient Pricer Payment System Tool. The SF-6D, a utility index derived from the SF-36v1, was used to determine quality-adjusted life years (QALY). Costs and QALYs were discounted at 3.5% annually.
  
  
  
  Of 580 surgical ASD patients eligible for 2-year follow up, 346 (60%) had complete baseline and 2-year data, and 60 were Medicare beneficiaries comprising the cohort for the present study. Mean SF-6D gained is 0.10 during year 1 after surgery and 0.02 at year 2, resulting in a cumulative SF-6D gain of 0.12 over 2 years. Mean Medicare allowable rate over the 2 years is $82,050 (range $42,383 to $220,749) and mean direct cost is $99,114 (range $28,447 to $217,717). Mean cost per QALY over 2 years is $683,750 using Medicare allowable rates and $825,950 using direct costs. This difference of $17,181 between the 2 cost calculation represents a 17% difference, which was statistically significant (p<.001).
  
  
  
  There is a significant difference in direct hospital costs versus Medicare allowable rates in ASD surgery and in turn, there is a similar difference in the cost per QALY calculation. Utilizing Medicare allowable rates not only underestimates (17%) the cost of ASD surgery, but it also creates inaccurate and unrealistic expectations for researchers and policymakers.
authors: Norton Leatherman Spine Center, 210 East Gray St, Suite 900, Louisville, KY 40202, USA.
authors: Jeffrey L
authors: JL
authors: Gum
authors: Baylor Scoliosis Center, 4708 Alliance Blvd, Suite 800, Plano, TX 75093, USA.
authors: Richard
authors: R
authors: Hostin
authors: Baylor Scott & White Health, Center for Clinical Effectiveness, 8080 N. Central Expressway, Ste. 500, Dallas, TX 75206, USA.
authors: Chessie
authors: C
authors: Robinson
authors: Department of Orthopedic Surgery, Institutes of Health, Washington University School of Medicine, 5th Fl, 660 S. Euclid Ave, Saint Louis, MO 63110, USA.
authors: Michael P
authors: MP
authors: Kelly
authors: Norton Leatherman Spine Center, 210 East Gray St, Suite 900, Louisville, KY 40202, USA. Electronic address: leah.carreon@nortonhealthcare.org.
authors: Leah Yacat
authors: LY
authors: Carreon
authors: Department of Orthopaedic Surgery, University of Minnesota, 2512 South 7th St, Suite R200, Minneapolis, MN 55454, USA.
authors: David W
authors: DW
authors: Polly
authors: Rocky Mountain Hospital for Children, Presbyterian/St. Luke's Medical Center, 2055 High St, Suite 130, Denver, CO 80205, USA.
authors: R Shay
authors: RS
authors: Bess
authors: Marc A Asher MD Comprehensive Spine Center, 3901 Rainbow Blvd MS 3017, Kansas City, KS 66160, USA.
authors: Douglas C
authors: DC
authors: Burton
authors: Department of Neurosurgery, University of Virginia, PO Box 800212, Charlottesville, VA 22908, USA.
authors: Christopher I
authors: CI
authors: Shaffrey
authors: Department of Neurosurgery, University of Virginia, PO Box 800212, Charlottesville, VA 22908, USA.
authors: Justin S
authors: JS
authors: Smith
authors: Department of Orthopaedic Surgery, New York Spine Institute, 761 Merrick Ave, Westbury, NY 11590, USA.
authors: Virginie
authors: V
authors: LaFage
authors: Department of Orthopaedic Surgery, New York Spine Institute, 761 Merrick Ave, Westbury, NY 11590, USA.
authors: Frank J
authors: FJ
authors: Schwab
authors: Department of Neurosurgery, University of California-San Francisco, 400 Parnassus Ave, San Francisco, CA 94143, USA.
authors: Christopher P
authors: CP
authors: Ames
authors: Norton Leatherman Spine Center, 210 East Gray St, Suite 900, Louisville, KY 40202, USA.
authors: Steven D
authors: SD
authors: Glassman
mesh_terms: D000368:Aged; D003362:Cost-Benefit Analysis; D005260:Female; D005102:Health Expenditures; D017721:Hospital Costs; D006801:Humans; D008297:Male; D006278:Medicare; D008875:Middle Aged; D013121:Spinal Curvatures / Q000191:economics* / Q000601:surgery; D013123:Spinal Fusion / Q000191:economics*; D014481:United States
keywords: Adult spine deformity surgery; Cost per QALY calculations; Cost-effectiveness; Hospital costs; Medicare allowable rates; Quality-adjusted life years