title: Sleep apnea and risk of deep vein thrombosis: a non-randomized, pair-matched cohort study.
abstract: BACKGROUND
  Patients with sleep apnea have been reported to be associated with increased prevalence of deep vein thrombosis (DVT) in some papers, which were criticized for either a small sample size or lack of a prospective control. Our study strived to explore the relationship of sleep apnea and the subsequent development of DVT using a nationwide, population-based database.
  
  
  METHODS
  From 2000 to 2007, we identified a study cohort consisting of newly diagnosed sleep apnea cases in the National Health Insurance Research Database. A control cohort without sleep apnea, matched for age, sex, comorbidities, major operation, and fractures, was selected for comparison. The 2 cohorts were followed-up, and we observed the occurrence of DVT by registry of DVT diagnosis.
  
  
  RESULTS
  Of the 10,185 sampled patients (5680 sleep apnea patients vs. 4505 control), 40 (0.39%) cases developed DVT during a mean follow-up period of 3.56 years, including 30 (0.53%) from the sleep apnea cohort and 10 (0.22 %) from the control group. Subjects with sleep apnea experienced a 3.113-fold (95% confidence interval, 1.516-6.390; P=.002) increase in incident DVT, which was independent of age, sex, and comorbidities. Kaplan-Meier analysis also revealed the tendency of sleep apnea patients toward DVT development (log-rank test, P=.001). The risk of DVT was even higher in sleep apnea cases who needed continuous positive airway pressure treatment (hazard ratio 9.575; 95% confidence interval, 3.181-28.818; P <.001).
  
  
  CONCLUSIONS
  Sleep apnea may be an independent risk factor for DVT.
authors.affiliation: Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Kun-Ta
authors.initials: KT
authors.lastname: Chou
authors.forename: Chin-Chou
authors.initials: CC
authors.lastname: Huang
authors.forename: Yuh-Min
authors.initials: YM
authors.lastname: Chen
authors.forename: Kang-Cheng
authors.initials: KC
authors.lastname: Su
authors.forename: Guang-Ming
authors.initials: GM
authors.lastname: Shiao
authors.forename: Yu-Chin
authors.initials: YC
authors.lastname: Lee
authors.forename: Wan-Leong
authors.initials: WL
authors.lastname: Chan
authors.forename: Hsin-Bang
authors.initials: HB
authors.lastname: Leu
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D016016:Proportional Hazards Models; D012307:Risk Factors; D012891:Sleep Apnea Syndromes / Q000150:complications / Q000453:epidemiology*; D013624:Taiwan / Q000453:epidemiology; D020246:Venous Thrombosis / Q000453:epidemiology* / Q000209:etiology