title: Proximate versus nonproximate risk factor associated primary deep venous thrombosis: clinical spectrum and outcomes.
abstract: OBJECTIVE
  Although the treatment for acute deep vein thrombosis (DVT) is uniform, the circumstances under which it develops vary widely and may impact outcomes. This study compared clinical features and outcomes in patients who developed a primary DVT associated with a defined risk to those without any proximate risk factor.
  
  
  METHODS
  Consecutive patients with a primary DVT and no past venous thromboembolism history from 2000 to 2002 were abstracted for demographics, risk factors, DVT anatomical characteristics, treatment, and outcomes of death and new pulmonary embolism. Comparison between patients with a proximate risk event within 30 days of DVT (Inpt) and those presenting with DVT with no defined proximate event (Outpt) was done by univariable and multivariable statistics. A validated survey was mailed to all living patients to assess long-term sequela.
  
  
  RESULTS
  A total of 293 patients with a mean age of 55 years and 49% men had confirmed DVT by objective means (92% duplex) with a mean follow-up of 25 +/- 21 months. Inpts were more likely to have recent surgery or blunt trauma, bilateral DVT, less use of low molecular weight heparin (LMWH), and new pulmonary emboli (all P <.05). Outpts with DVT were more likely to have a history of malignancy, tibial-popliteal DVT compared with iliofemoral DVT, higher use of LMWH, and coumadin. However, there was no difference in mortality. From the patient survey (21% response), Outpts were more likely than Inpts to develop later varicosities and have daily frustration related to their legs (P < .05), but no difference in edema or ulceration. Considering the entire group, independent factors associated with freedom from PE included ambulation (odds ratio [OR] = 2.3; 95% confidence interval [CI] = 1.1-5.0; P = .04) while bilateral DVT (OR = .26; 95% CI = .09-.76; P = .013) or subcutaneous heparin (OR = 22; 95% CI = .05-.98; P = .047) were associated with greater risk. Independent factors associated with survival included ambulation (OR = 3.0; 95% CI = 1.3-7.2; P = .02), Coumadin use (OR = 2.7; 95% CI = 1.2-6.1; P = .015), and tibiopopliteal DVT (OR = 2.4; 95% = 1.1-5.5; P = .03), while malignancy (OR = 0.1; 95% CI = .05-.24; P < .01) and myocardial infarction (OR = 0.12; 95% CI = .01-.92; P = .04) were associated with lower survival.
  
  
  CONCLUSIONS
  Patients who develop DVT related to a defined proximate risk event (Inpt) generally have more extensive DVT, an increased risk of PE, but less long-term functional morbidity and no difference in long-term mortality compared to those with no proximate risk.
authors.affiliation: Section of Vascular Surgery, University of Michigan, School of Medicine, Ann Arbor, MI 48109, USA. henke@umich.edu <henke@umich.edu>
authors.forename: Peter K
authors.initials: PK
authors.lastname: Henke
authors.forename: Eric
authors.initials: E
authors.lastname: Ferguson
authors.forename: Manu
authors.initials: M
authors.lastname: Varma
authors.forename: K Barry
authors.initials: KB
authors.lastname: Deatrick
authors.forename: G Thomas W
authors.initials: GT
authors.lastname: Wakefield
authors.forename: Derek T
authors.initials: DT
authors.lastname: Woodrum
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000453:epidemiology; D012307:Risk Factors; D020246:Venous Thrombosis / Q000453:epidemiology* / Q000628:therapy