title: Impact of magnitude and percentage of global sagittal plane correction on health-related quality of life at 2-years follow-up.
abstract: BACKGROUND
  Sagittal plane malalignment has been established as the main radiographic driver of disability in adult spinal deformity (ASD).
  
  
  OBJECTIVE
  To evaluate the amount of sagittal correction needed for a patient to perceive improvement (minimal clinically important difference, MCID) in health-related quality of life (HRQOL) scores.
  
  
  METHODS
  This was a multicenter, retrospective analysis of prospectively consecutively enrolled ASD patients. Inclusion criterion was a sagittal vertical axis (SVA) >80 mm. Demographic, radiographic, and HRQOL preoperative and 2-year postsurgery data were collected. Surgical treatment was categorized based on SVA correction: <60 mm, 60 mm to 120 mm, and >120 mm. Changes in parameters were analyzed using paired t test, 1-way analysis of variance, and χ2 test.
  
  
  RESULTS
  Seventy-six patients (preoperative SVA = 140 mm) were analyzed; each subgroup revealed significant HRQOL improvements following surgery. Compared with the <60 mm correction group, the likelihood of reaching MCID was significantly improved for the >120 mm group (Oswestry Disability Index) but not for the 60 mm to 120 mm group. A significantly greater likelihood of reaching MCID thresholds was observed for corrections above 66% of preoperative SVA.
  
  
  CONCLUSIONS
  Best HRQOL outcomes for ASD patients with severe sagittal plane deformity were obtained with a correction >120 mm for SVA and at least 66% of correction. Although lesser amounts of SVA correction yielded clinical improvement, the rate of MCID threshold improvement was not significantly different for mild or modest corrections. These results underline the need for complete sagittal plane deformity correction if high rates of HRQOL benefit are sought for patients with marked sagittal plane deformity.
authors.affiliation: Spine Division, Hospital for Joint Diseases, New York University, New York, New York 10003, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Blondel
authors.forename: Frank
authors.initials: F
authors.lastname: Schwab
authors.forename: Benjamin
authors.initials: B
authors.lastname: Ungar
authors.forename: Justin
authors.initials: J
authors.lastname: Smith
authors.forename: Keith
authors.initials: K
authors.lastname: Bridwell
authors.forename: Steven
authors.initials: S
authors.lastname: Glassman
authors.forename: Christopher
authors.initials: C
authors.lastname: Shaffrey
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Farcy
authors.forename: Virginie
authors.initials: V
authors.lastname: Lafage
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011788:Quality of Life; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D020127:Recovery of Function; D015203:Reproducibility of Results; D012600:Scoliosis / Q000175:diagnosis* / Q000453:epidemiology / Q000601:surgery*; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology