title: Association Between Obstructive Sleep Apnea and Osteoporosis: A Systematic Review and Meta-Analysis.
abstract: BACKGROUND
  Hypoxia reduces osteoblast growth resulting in bone thinning and osteoporosis. Although obstructive sleep apnea (OSA) with recurrent hypoxia might be a contributing factor for osteoporosis development, whether OSA is a risk or protective factor for osteoporosis has not been demonstrated.
  
  
  OBJECTIVE
  This systematic review and meta-analysis evaluated the association between OSA and osteoporosis using published observational studies.
  
  
  METHODS
  PubMed/MEDLINE and EMBASE databases.
  
  
  METHODS
  We completed a systematic review and meta-analysis of published observational studies that evaluated incidence or prevalence of osteoporosis or bone mineral density in obstructive sleep apnea compared with controls. Severity of OSA was characterized using the apnea-hypopnea index (AHI).
  
  
  METHODS
  Primary outcomes were incidence, prevalence, or odds ratio of having osteoporosis, defined as bone mineral density T-score < -2.5 SD.
  
  
  RESULTS
  Of 353 articles, 344 articles were excluded, 9 underwent full-length review and data were extracted from 7 studies consisting of 113,558 patients. Finally, 3 extracted studies were included in the meta-analysis of osteoporosis. Among cohort studies, the pooled odds ratio of osteoporosis in patients with OSA was 1.92 (95% confidence interval [CI]: 1.24 - 2.97) compared with controls. Among cross-sectional studies, odds of osteoporosis was higher in controls compared with patients with OSA (OR = 0.60, 95% CI: 0.42 - 0.87). In subgroup analysis by gender and study design, in both sexes, only cohort studies had higher odds of osteoporosis compared with controls.
  
  
  CONCLUSIONS
  There was significant association between OSA and osteoporosis in studies with cohort design. Further prospective studies with large numbers of patients adjusted for the effects of age, sex, or BMI are required to comprehensively determine whether OSA is a risk factor for osteoporosis.
authors.affiliation: Department of Internal Medicine, College of Physicians and Surgeons, Bassett Medical Center and Columbia University, New York, USA; Department of Preventive and Social Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Sikarin
authors.initials: S
authors.lastname: Upala
authors.affiliation: Department of Internal Medicine, College of Physicians and Surgeons, Bassett Medical Center and Columbia University, New York, USA; Department of Preventive and Social Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Anawin
authors.initials: A
authors.lastname: Sanguankeo
authors.affiliation: Department of Medicine, St. Elizabeth's Medical Center, Boston, Massachusetts, USA.
authors.forename: Soontharee
authors.initials: S
authors.lastname: Congrete
keywords: Meta-Analysis; Obstructive Sleep Apnea; Osteoporosis; Risk; Systematic Review