title: Associated bone mineral density and obstructive sleep apnea in chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Osteoporosis is an important issue for patients with chronic obstructive pulmonary disease (COPD). Worse systemic inflammation and reduced exercise capacity have been reported in COPD patients with obstructive sleep apnea (OSA), implying that OSA may be an independent factor for osteoporosis in COPD patients.
  
  
  METHODS
  A total of 66 patients with bone mineral density (BMD) and polysomnography results from a previous COPD cohort (January 2008 to January 2013) were retrospectively enrolled. Clinical characteristics such as medication, pulmonary function, BMD, and results of polysomnography were analyzed.
  
  
  RESULTS
  The BMD in those with OSA was significantly lower than in those without OSA (-1.99±1.63 versus -1.27±1.14, P=0.045). In univariate analysis, body mass index, forced expiratory volume in 1 second, percentage of predicted value, incremental shuttle walk test, apnea-hypopnea index, and oxygen desaturation index (ODI) were significantly associated with BMD. After multivariate linear regression analysis, the ODI was still an independent factor for BMD. In addition, smaller total lung capacity is significantly associated with higher ODI and lower BMD, which implies that lower BMD might cause severer OSA via decreased total lung capacity.
  
  
  CONCLUSIONS
  OSA may be an independent factor for BMD in patients with COPD, which implies a possible vicious cycle takes place in these patients.
authors: Department of Thoracic Medicine, School of Medicine, Chang Gung Memorial Hospital and Chang Gung University, Taipei, Taiwan.
authors: Tsai-Yu
authors: TY
authors: Wang
authors: Department of Thoracic Medicine, School of Medicine, Chang Gung Memorial Hospital and Chang Gung University, Taipei, Taiwan ; Healthcare Center, Chang Gung Memorial Hospital, Taipei, Taiwan.
authors: Yu-Lun
authors: YL
authors: Lo
authors: Department of Thoracic Medicine, School of Medicine, Chang Gung Memorial Hospital and Chang Gung University, Taipei, Taiwan.
authors: Pai-Chien
authors: PC
authors: Chou
authors: Department of Thoracic Medicine, School of Medicine, Chang Gung Memorial Hospital and Chang Gung University, Taipei, Taiwan.
authors: Fu-Tsai
authors: FT
authors: Chung
authors: Department of Thoracic Medicine, School of Medicine, Chang Gung Memorial Hospital and Chang Gung University, Taipei, Taiwan.
authors: Shu-Min
authors: SM
authors: Lin
authors: Department of Thoracic Medicine, School of Medicine, Chang Gung Memorial Hospital and Chang Gung University, Taipei, Taiwan.
authors: Ting-Yu
authors: TY
authors: Lin
authors: Department of Thoracic Medicine, School of Medicine, Chang Gung Memorial Hospital and Chang Gung University, Taipei, Taiwan.
authors: Horng-Chyuan
authors: HC
authors: Lin
authors: Department of Thoracic Medicine, School of Medicine, Chang Gung Memorial Hospital and Chang Gung University, Taipei, Taiwan.
authors: Chun-Hua
authors: CH
authors: Wang
authors: Department of Thoracic Medicine, School of Medicine, Chang Gung Memorial Hospital and Chang Gung University, Taipei, Taiwan.
authors: Chih-Teng
authors: CT
authors: Yu
authors: Department of Thoracic Medicine, School of Medicine, Chang Gung Memorial Hospital and Chang Gung University, Taipei, Taiwan.
authors: Han-Pin
authors: HP
authors: Kuo
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D015519:Bone Density; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D016014:Linear Models; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010024:Osteoporosis / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D017286:Polysomnography; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology
keywords: chronic obstructive pulmonary disease; osteoporosis; total lung capacity