title: Body Mass Index and Risk for Clinical Lumbar Spinal Stenosis: A Cohort Study.
abstract: METHODS
  A prospective cohort study that used a Swedish nationwide occupational surveillance program for construction workers (period of registration from 1971 to 1992). In all, 364,467 participants (mean age at baseline 34 yr) were included in the study.
  
  
  OBJECTIVE
  To determine whether overweight and obesity are associated with a higher risk of lumbar spinal stenosis (LSS).
  
  
  BACKGROUND
  During recent decades, LSS has become the most common indication for spine surgery, a change that coincides with a higher prevalence of obesity.
  
  
  METHODS
  A diagnosis of LSS was collected through individual linkage to the Swedish National Patient Register through December 31, 2011. Poisson regression models were employed to estimate multivariable-adjusted incidence rate ratios (IRRs) for LSS.
  
  
  RESULTS
  At baseline, 65% had normal weight (BMI [body mass index]: 18.5-24.99 kg/m), 29% were overweight (BMI: 25-29.99 kg/m), 5% were obese (BMI ≥30 kg/m), and 2% were underweight (BMI <18.5 kg/m). During 11,190,944 person-years of follow-up, with a mean of 31 years, 2381 participants were diagnosed with LSS. Compared with normal weight individuals, obese workers had an IRR of 2.18 (95% confidence interval, 1.87-2.53) for LSS and overweight workers had an IRR of 1.68 (95% confidence interval, 1.54-1.83). Workers who were underweight halved their risk of LSS (IRR: 0.52, 95% confidence interval, 0.30-0.90).
  
  
  CONCLUSIONS
  Obese and overweight persons are at a higher risk of developing LSS. Furthermore, our results indicate that obesity might be a novel explanation for the increased number of patients with clinical LSS.
  
  
  METHODS
  3.
authors.affiliation: *Department of Surgical Sciences, Section of Orthopedics, Uppsala University, Uppsala, Sweden Department of †Surgical and Perioperative Science and ‡Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
authors.forename: Björn
authors.initials: B
authors.lastname: Knutsson
authors.forename: Bengt
authors.initials: B
authors.lastname: Sandén
authors.forename: Göran
authors.initials: G
authors.lastname: Sjödén
authors.forename: Bengt
authors.initials: B
authors.lastname: Järvholm
authors.forename: Karl
authors.initials: K
authors.lastname: Michaëlsson
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D006801:Humans; D015994:Incidence; D008159:Lumbar Vertebrae; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017711:Nonlinear Dynamics; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology*; D016272:Occupational Health; D011446:Prospective Studies; D065840:Protective Factors; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D013130:Spinal Stenosis / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D013548:Sweden / Q000453:epidemiology; D013851:Thinness / Q000175:diagnosis / Q000453:epidemiology*; D013997:Time Factors; D055815:Young Adult