title: Performing a cost analysis in spine outcomes research:  comparing ventral and dorsal approaches for cervical spondylotic myelopathy.
abstract: BACKGROUND
  Medical cost analysis is increasingly important, but the methodology is complex and varied.
  
  
  OBJECTIVE
  To illustrate how different cost analysis methodologies influence conclusions generated from data from a prospective nonrandomized trial for treatment of cervical spondylotic myelopathy.
  
  
  METHODS
  Patients 40 to 85 years of age with degenerative cervical spondylotic myelopathy were enrolled from 7 sites over 2 years (2007-2009). Patients were treated with ventral or dorsal fusion surgery, and outcomes were measured to 1 year postoperatively. A hospital-based cost analysis was performed using Medicare cost-to-charge ratios (CCRs) multiplied by hospital charges from the index hospitalization (CCR method). A society-based cost analysis was performed by estimating costs from the index hospitalization using Medicare coding reimbursement (the Medicare reimbursement method). A separate outpatient cost analysis was performed on a subset of 20 patients.
  
  
  RESULTS
  Of the 85 patients analyzed, 72 had 1-year follow-up. The CCR method showed a difference in upfront direct costs between the dorsal and ventral approaches ($27,942 ± 14,220 vs $21,563 ± 8721; P = .02). Overall upfront direct costs with the Medicare reimbursement method were not different. With the CCR method, the ventral approach dominates an incremental cost-effectiveness ratio analysis. With the Medicare reimbursement method, the incremental cost-effectiveness ratio for ventral surgery is $34,533, the cost of 1 additional quality-adjusted life-year gained by using ventral instead of dorsal surgery. In the subanalysis, outpatient costs were less after ventral surgery than dorsal surgery ($1997 ± 1211 vs $4734 ± $2874; P = .006).
  
  
  CONCLUSIONS
  The choice of cost methodology may substantially influence the final results of an economic study.
authors.affiliation: Department of Neurosurgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Whitmore
authors.forename: J Sanford
authors.initials: JS
authors.lastname: Schwartz
authors.forename: Sydney
authors.initials: S
authors.lastname: Simmons
authors.forename: Sherman C
authors.initials: SC
authors.lastname: Stein
authors.forename: Zoher
authors.initials: Z
authors.lastname: Ghogawala
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae; D003365:Costs and Cost Analysis / Q000379:methods*; D006801:Humans; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D019057:Quality-Adjusted Life Years; D013123:Spinal Fusion / Q000191:economics* / Q000379:methods*; D055009:Spondylosis / Q000191:economics* / Q000601:surgery; D016896:Treatment Outcome