title: Major medical outcomes with spinal augmentation vs conservative therapy.
abstract: OBJECTIVE
  The symptomatic benefits of spinal augmentation (vertebroplasty or kyphoplasty) for the treatment of osteoporotic vertebral compression fractures are controversial. Recent population-based studies using medical billing claims have reported significant reductions in mortality with spinal augmentation compared with conservative therapy, but in nonrandomized settings such as these, there is the potential for selection bias to influence results.
  
  
  OBJECTIVE
  To compare major medical outcomes following treatment of osteoporotic vertebral fractures with spinal augmentation or conservative therapy. Additionally, we evaluate the role of selection bias using preprocedure outcomes and propensity score analysis.
  
  
  METHODS
  Retrospective cohort analysis of Medicare claims for the 2002-2006 period. We compared 30-day and 1-year outcomes in patients with newly diagnosed vertebral fractures treated with spinal augmentation (n = 10,541) or conservative therapy (control group, n = 115,851). Outcomes were compared using traditional multivariate analyses adjusted for patient demographics and comorbid conditions. We also used propensity score matching to select 9017 pairs from the initial groups to compare the same outcomes.
  
  
  METHODS
  Spinal augmentation (vertebroplasty or kyphoplasty) or conservative therapy.
  
  
  METHODS
  Mortality, major complications, and health care utilization.
  
  
  RESULTS
  Using traditional covariate adjustments, mortality was significantly lower in the augmented group than among controls (5.2% vs 6.7% at 1 year; hazard ratio, 0.83; 95% CI, 0.75-0.92). However, patients in the augmented group who had not yet undergone augmentation (preprocedure subgroup) had lower rates of medical complications 30 days post fracture than did controls (6.5% vs 9.5%; odds ratio, 0.66; 95% CI, 0.57-0.78), suggesting that the augmented group was less medically ill. After propensity score matching to better account for selection bias, 1-year mortality was not significantly different between the groups. Furthermore, 1-year major medical complications were also similar between the groups, and the augmented group had higher rates of health care utilization, including hospital and intensive care unit admissions and discharges to skilled nursing facilities.
  
  
  CONCLUSIONS
  After accounting for selection bias, spinal augmentation did not improve mortality or major medical outcomes and was associated with greater health care utilization than conservative therapy. Our results also highlight how analyses of claims-based data that do not adequately account for unrecognized confounding can arrive at misleading conclusions.
authors.affiliation: Department of Radiology, University of Washington, Seattle.
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: McCullough
authors.forename: Bryan A
authors.initials: BA
authors.lastname: Comstock
authors.forename: Richard A
authors.initials: RA
authors.lastname: Deyo
authors.forename: William
authors.initials: W
authors.lastname: Kreuter
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Jarvik
mesh_terms: D000369:Aged, 80 and over; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data; D053208:Kaplan-Meier Estimate; D058498:Kyphoplasty; D008297:Male; D015999:Multivariate Analysis; D058866:Osteoporotic Fractures / Q000150:complications / Q000401:mortality / Q000628:therapy*; D010343:Patient Admission / Q000706:statistics & numerical data; D057216:Propensity Score; D012189:Retrospective Studies; D012866:Skilled Nursing Facilities / Q000706:statistics & numerical data; D016103:Spinal Fractures / Q000150:complications / Q000401:mortality / Q000628:therapy*; D054854:Vertebroplasty