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Impact of Magnitude and Percentage of Global Sagittal Plane Correction on Health-Related Quality of Life at 2-Years Follow-Up

Blondel, Benjamin MD*,‡; Schwab, Frank MD*; Ungar, Benjamin BA*; Smith, Justin MD, PhD§; Bridwell, Keith MD; Glassman, Steven MD; Shaffrey, Christopher MD§; Farcy, Jean-Pierre MD#; Lafage, Virginie PhD*

Neurosurgery:
doi: 10.1227/NEU.0b013e31825d20c0
Research-Human-Clinical Studies
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.

CONCLUSION: 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.

ABBREVIATIONS: ASD, adult spinal deformity

HRQOL, health-related quality of life

LL, lumbar lordosis

MCID, minimal clinically important difference

ODI, Oswestry Disability Index

PCS, Physical Component Score

PT, pelvic tilt

SCB, substantial clinical benefit

SRS, Scoliosis Research Society

SVA, sagittal vertical axis

TK, thoracic kyphosis

Author Information

*Spine Division, Hospital for Joint Diseases, New York University, New York, New York

Université Aix-Marseille, Marseille, France

§Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia

Spine department, Washington University School of Medicine, Saint Louis, Missouri

Spine Institute for Special Surgery, University of Louisville, Kentucky

#Maimonides Medical Center, Brooklyn, New York

Correspondence: Virginie Lafage, PhD, Spine Division, Hospital for Joint Diseases, New York University, New York, NY 10003. E-mail: virginie.lafage@gmail.com

Received September 13, 2011

Accepted April 4, 2012

Copyright © by the Congress of Neurological Surgeons