title: Primary venous insufficiency increases risk of deep vein thrombosis.
abstract: BACKGROUND
  Varicose veins have been recognized as a risk factor for deep vein thrombosis (DVT). However, venous reflux has not carried the same correlation. This study evaluated the association between primary valvular reflux and DVT.
  
  
  METHODS
  We performed a nested case-control study with enrollment of outpatients presenting to the vascular laboratory with signs and symptoms of DVT. All patients had a complete bilateral venous duplex examination evaluating for DVT and superficial and deep venous valvular reflux. Eighty-seven patients with confirmed DVT on venous duplex were selected for the study group. The control group was randomly selected from the same cohort in a 4:1 ratio matched by age and gender (n = 348). Groups were compared for the prevalence of deep and superficial reflux.
  
  
  RESULTS
  DVT outpatients were 4.7-times more likely to have primary valvular reflux than symptomatic controls (65.5% vs 29.0%; 95% confidence interval [CI], 2.8-7.7; P < .000001). Deep reflux was 2.1-times more prevalent (36.8% vs 21.6%; odds ratio, 2.12; 95% CI, 1.28-3.51; P = .005) and superficial reflux was 4.6-times more prevalent (43.7% vs 14.4%; odds ratio, 4.62; 95% CI, 2.75-7.77; P < .0000001) in DVT patients than in controls. DVT patients were also 2.1-times more likely to have combined deep and superficial reflux than non-DVT patients (13.8% vs 6.6%, 95% CI, 1.08-4.75; P = .044).
  
  
  CONCLUSIONS
  The prevalence of primary valvular reflux in patients with DVT is significantly higher than expected. Reflux may be considered as a novel risk factor for DVT. Two-thirds of patients with DVT have pre-existent primary chronic venous disease, which is likely to contribute to post-thrombotic morbidity.
authors.affiliation: Jobst Vascular Institute, ProMedica Toledo Hospital, Toledo, Ohio.
authors.forename: Maxim E
authors.initials: ME
authors.lastname: Shaydakov
authors.affiliation: Jobst Vascular Institute, ProMedica Toledo Hospital, Toledo, Ohio.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Comerota
authors.affiliation: Jobst Vascular Institute, ProMedica Toledo Hospital, Toledo, Ohio. Electronic address: shakela.watkins@promedica.org.
authors.forename: Fedor
authors.initials: F
authors.lastname: Lurie
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002908:Chronic Disease; D005260:Female; D005268:Femoral Vein; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012306:Risk; D012307:Risk Factors; D014648:Varicose Veins / Q000150:complications; D014689:Venous Insufficiency / Q000150:complications*; D020246:Venous Thrombosis / Q000150:complications*