title: Airflow limitation as a risk factor for low bone mineral density and hip fracture.
abstract: OBJECTIVE
  To investigate whether airflow limitation is associated with bone mineral density (BMD) and risk of hip fractures.
  
  
  METHODS
  A community sample of 5,100 subjects 47-48 and 71-73 years old and living in Bergen was invited. Participants filled in questionnaires and performed a post-bronchodilator spirometry measuring forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC). All attendants were invited to have a BMD measurement of the hip. During 10 years of follow-up, information on death was collected from the Norwegian Cause of Death Registry, and incident hip fractures were registered from regional hospital records of discharge diagnoses and surgical procedure codes.
  
  
  RESULTS
  The attendance rate was 69% (n=3,506). The prevalence of chronic obstructive pulmonary disease (COPD) (FEV1/FVC<0.7) was 9%. In multiple logistic regression, the lowest quartile of BMD versus the three upper was significantly predicted by FEV1/FVC<0.7 and FEV1% predicted (odds ratio [OR]: 1.58, 95% confidence interval [CI]: 1.11 to 2.25, and OR per increase of 10%: 0.92, 95% CI: 0.86 to 0.99, respectively). Hip fracture occurred in 126 (4%) participants. In a Cox regression analysis, FEV1% predicted was associated with a lowered risk of hip fracture (hazard ratio per increase of 10%: 0.89, 95% CI: 0.79 to 0.997).
  
  
  CONCLUSIONS
  Airflow limitation is positively associated with low BMD and risk of hip fracture in middle-aged and elderly.
authors.affiliation: Department of Clinical Science, University of Bergen, Bergen, Norway; trine@herland.nu.
authors.forename: Trine
authors.initials: T
authors.lastname: Herland
authors.affiliation: Department of Rheumatology, Haukeland University Hospital, Bergen, Norway.|Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Apalset
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.|Centre for Clinical Research, Haukeland University Hospital, Bergen, Norway.
authors.forename: Geir Egil
authors.initials: GE
authors.lastname: Eide
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.
authors.forename: Grethe S
authors.initials: GS
authors.lastname: Tell
authors.affiliation: Department of Clinical Science, University of Bergen, Bergen, Norway.|Department of Thoracic Medicine, Haukeland University Hospital, Bergen, Norway.
authors.forename: Sverre
authors.initials: S
authors.lastname: Lehmann
keywords: airflow limitation; bone mineral density; hip fracture; lung function; population study