title: Risk factors associated with the occurrence of silent pulmonary embolism in patients with deep venous thrombosis of the lower limb.
abstract: OBJECTIVE
  The aim of our study is to investigate the prevalence of silent pulmonary embolism in patients with deep venous thrombosis in the lower limbs and to evaluate the associated risk factors.
  
  
  METHODS
  A total of 322 patients with acute deep venous thrombosis confirmed by CT venography or Doppler ultrasonography were studied. The diagnosis of silent pulmonary embolism was established by computed tomography pulmonary arteriography (CTPA). The association between covariates and the prevalence of silent pulmonary embolism in patients with deep venous thrombosis in lower limbs were assessed using chi-square test and multivariable regression.
  
  
  RESULTS
  The incidence of silent pulmonary embolism was 33.5% (108 in 322 patients) in all patients with deep venous thrombosis in lower limbs. Chi-square test showed male gender, the right lower limb, proximal location of the thrombus, unprovoked venous thrombosis and coexisting heart diseases were related to a higher incidence of silent pulmonary embolism in patients with deep venous thrombosis in lower limbs. The multivariate regression analysis confirmed that the risk factors associated with silent pulmonary embolism in deep venous thrombosis patients included the right side and proximal location of the thrombus (odds ratio: 2.023, 95% CI: 1.215-3.368; odds ratio: 3.610, 95% CI: 1.772-7.354), unprovoked venous thrombosis (odds ratio: 2.037, 95% CI: 1.188-3.493), coexisting heart diseases (odds ratio: 4.507, 95% CI: 2.667-7.618).
  
  
  CONCLUSIONS
  Silent pulmonary embolism occurred frequently in patients with deep venous thrombosis in lower limbs. The right side, the proximal location of the thrombus, unprovoked venous thrombosis and coexisting heart diseases increased the risk for the occurrence of silent pulmonary embolism.
authors.affiliation: Department of Vascular Sugery, 1st Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Fenghe
authors.initials: F
authors.lastname: Li
authors.affiliation: Department of Vascular Sugery, 1st Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Xuehu
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Vascular Sugery, 1st Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Huang
authors.affiliation: Department of Vascular Sugery, 1st Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ren
authors.affiliation: Department of Radialogy, 1st Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Department of Vascular Sugery, 1st Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Mao
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Vascular Sugery, 1st Hospital of Chongqing Medical University, Chongqing, China zy_cqmu@hotmail.com.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058070:Asymptomatic Diseases; D016009:Chi-Square Distribution; D002681:China / Q000453:epidemiology; D015897:Comorbidity; D005260:Female; D006331:Heart Diseases / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D035002:Lower Extremity / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010690:Phlebography / Q000379:methods; D011237:Predictive Value of Tests; D015995:Prevalence; D011655:Pulmonary Embolism / Q000175:diagnosis / Q000453:epidemiology*; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D018608:Ultrasonography, Doppler; D020246:Venous Thrombosis / Q000175:diagnosis / Q000453:epidemiology*; D055815:Young Adult
keywords: Deep venous thrombosis; lower limb; risk factors; silent pulmonary embolism