title: The impact of obesity on short- and long-term outcomes after lumbar fusion.
abstract: METHODS
  Retrospective cohort study.
  
  
  OBJECTIVE
  To compare short- and long-term outcomes in obese versus nonobese patients undergoing instrumented posterolateral fusion of the lumbar spine.
  
  
  BACKGROUND
  Obesity is an important public health issue due to the negative effects on quality of life. Some studies have shown an association between obesity and higher rates of complications and unfavorable outcomes after spine surgery.
  
  
  METHODS
  We retrospectively reviewed medical records for all adult patients undergoing 1- to 3-level posterolateral fusion for degenerative spine disease between 1992 and 2012 at a single institution. Patients were divided into obese (body mass index > 30 kg/m) and nonobese cohorts to compare complications, reoperation rates, and symptom resolution at the last follow-up. A regression model was used to estimate relative risk ratios.
  
  
  RESULTS
  During the study period, 732 patients underwent lumbar fusion, with 662 (90.44%) nonobese patients and 70 (9.56%) obese patients in the cohort. Obese patients had significantly higher blood loss intraoperatively (P = 0.002) and a longer average length of stay (P = 0.022). Moreover, obesity was independently associated with a significantly increased risk of developing a postoperative complication (risk ratio 2.14; 95% confidence interval, 1.10-4.16) and surgical site infection (risk ratio 3.11; 95% confidence interval, 1.48-6.52). At the last follow-up, a higher proportion of obese patients had radiculopathy (P = 0.018), motor deficits (P = 0.006), sensory deficits (P = 0.008), and bowel or bladder dysfunction (P = 0.006) than nonobese patients.
  
  
  CONCLUSIONS
  In this study, obese patients undergoing lumbar fusion had higher blood loss, longer lengths of stay, higher complication rates, and worse functional outcomes at the last follow-up than nonobese patients. These findings suggest that both surgeons and patients should acknowledge the significantly increased morbidity profile of obese patients after lumbar fusion.
authors.affiliation: *The Spinal Column Biomechanics and Surgical Outcomes Laboratory †Department of Neurosurgery, and ‡Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Rafael
authors.initials: R
authors.lastname: De la Garza-Ramos
authors.forename: Mohamad
authors.initials: M
authors.lastname: Bydon
authors.forename: Nicholas B
authors.initials: NB
authors.lastname: Abt
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Sciubba
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Wolinsky
authors.forename: Ali
authors.initials: A
authors.lastname: Bydon
authors.forename: Ziya L
authors.initials: ZL
authors.lastname: Gokaslan
authors.forename: Bruce
authors.initials: B
authors.lastname: Rabin
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Witham
mesh_terms: D000328:Adult; D000368:Aged; D016063:Blood Loss, Surgical; D015992:Body Mass Index; D003672:Defecation; D005260:Female; D006801:Humans; D007902:Length of Stay; D008159:Lumbar Vertebrae / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D011843:Radiculopathy / Q000209:etiology; D012086:Reoperation; D012189:Retrospective Studies; D012678:Sensation Disorders / Q000209:etiology; D013123:Spinal Fusion / Q000009:adverse effects* / Q000379:methods; D013130:Spinal Stenosis / Q000150:complications / Q000601:surgery; D013530:Surgical Wound Infection / Q000209:etiology*; D013997:Time Factors; D016896:Treatment Outcome; D014555:Urination Disorders / Q000209:etiology