title: The Impact of Obesity on the Outcome of Decompression Surgery in Degenerative Lumbar Spinal Canal Stenosis: Analysis of the Lumbar Spinal Outcome Study (LSOS): A Swiss Prospective Multicenter Cohort Study.
abstract: METHODS
  Prospective, multicenter cohort study including 8 medical centers of the Cantons Zurich, Lucerne, and Thurgau, Switzerland.
  
  
  OBJECTIVE
  The aim of the study was to assess whether obese patients benefit after decompression surgery for degenerative lumbar spinal stenosis (DLSS).
  
  
  BACKGROUND
  Lumbar decompression surgery has been shown to improve quality of life in patients with DLSS. In the existing literature, the efficacy of lumbar decompression in the obese population remains controversial.
  
  
  METHODS
  Baseline patient characteristics and outcomes were analyzed at 6 and 12 months follow-up with the Spinal Stenosis Measure (SSM), the Numeric Rating Scale (NRS), Feeling Thermometer (FT), the EQ-5D-EL, and the Roland and Morris Disability Questionnaire (RMDQ). Body mass index (BMI) was classified into 3 categories according to the WHO. Minimal clinically important differences (MCIDs) in SSM for different BMI categories were considered as main outcome.
  
  
  RESULTS
  Of the 656 patients in the Lumbar Spinal Outcome Study database as of end of October 2014, 166 patients met the inclusion criteria. Fifty (30.1%) had a BMI less than 25 (underweight and normal weight group), 72 (43.4%) had a BMI between 25 and less than 30 (preobesity group), and 44 (26.5%) patients had a BMI at least 30 (obese group). We found for the main outcome that in obese patients 36% reached MCID at 6 months, and 48% at 12 months. The estimated odds ratios for MCID in the obese group were 0.78 (0.34-1.82) at 6 months and 0.99 (0.44-2.23) at 12 months in a logistic regression model adjusting for levels of laminectomy. In the additional outcomes, SSM, NRS, FT, and RMDQ showed statistically significant mean improvements in the 6 and 12 months follow-up.
  
  
  CONCLUSIONS
  Obese patients can expect clinical improvement after lumbar decompression for DLSS, but the percentage of patients with a meaningful improvement is lower than in the group of patients with underweight, normal weight, and preobese weight at 6 and 12 months.
authors.affiliation: *Horten Centre for Patient Oriented Research and Knowledge Transfer, University of Zurich, Switzerland †Spine Division, Balgrist University Hospital, University of Zürich, Switzerland ‡Department of Orthopedics and Neurosurgery, Spine Center, Schulthess Clinic, Zurich, Switzerland.
authors.forename: Jakob M
authors.initials: JM
authors.lastname: Burgstaller
authors.forename: Ulrike
authors.initials: U
authors.lastname: Held
authors.forename: Florian
authors.initials: F
authors.lastname: Brunner
authors.forename: François
authors.initials: F
authors.lastname: Porchet
authors.forename: Mazda
authors.initials: M
authors.lastname: Farshad
authors.forename: Johann
authors.initials: J
authors.lastname: Steurer
authors.forename: Nils H
authors.initials: NH
authors.lastname: Ulrich
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019299:Decompression, Surgical / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D009765:Obesity / Q000453:epidemiology*; D013130:Spinal Stenosis / Q000601:surgery*; D016896:Treatment Outcome