title: Low-molecular-weight or unfractionated heparin in venous thromboembolism: the influence of renal function.
abstract: BACKGROUND
  In patients with acute venous thromboembolism and renal insufficiency, initial therapy with unfractionated heparin may have some advantages over low-molecular-weight heparin.
  
  
  METHODS
  We used the Registro Informatizado de la Enfermedad TromboEmbólica (RIETE) Registry data to evaluate the 15-day outcome in 38,531 recruited patients. We used propensity score matching to compare patients treated with unfractionated heparin with those treated with low-molecular-weight heparin in 3 groups stratified by creatinine clearance levels at baseline: >60 mL/min, 30 to 60 mL/min, or <30 mL/min.
  
  
  RESULTS
  Patients initially receiving unfractionated heparin therapy (n = 2167) more likely had underlying diseases than those receiving low-molecular-weight heparin (n = 34,665). Propensity score-matched groups of patients with creatinine clearance levels >60 mL/min (n = 1598 matched pairs), 30 to 60 mL/min (n = 277 matched pairs), and <30 mL/min (n = 210 matched pairs) showed an increased 15-day mortality for unfractionated heparin compared with low-molecular-weight heparin (4.5% vs 2.4% [P = .001], 5.4% vs 5.8% [P = not significant], and 15% vs 8.1% [P = .02], respectively), an increased rate of fatal pulmonary embolism (2.8% vs 1.2% [P = .001], 3.2% vs 2.5% [P = not significant], and 5.7% vs 2.4% [P = .02], respectively), and a similar rate of fatal bleeding (0.3% vs 0.3%, 0.7% vs 0.7%, and 0.5% vs 0.0%, respectively). Multivariate analysis confirmed that patients treated with unfractionated heparin were at increased risk for all-cause death (odds ratio, 1.8; 95% confidence interval, 1.3-2.4) and fatal pulmonary embolism (odds ratio, 2.3; 95% confidence interval, 1.5-3.6).
  
  
  CONCLUSIONS
  In comparison with low-molecular-weight heparin, initial therapy with unfractionated heparin was associated with a higher mortality and higher rate of fatal pulmonary embolism in patients with creatinine clearance levels >60 mL/min or <30 mL/min, but not in those with levels between 30 and 60 mL/min.
authors.affiliation: Department of Internal Medicine, Hospital Universitario de Santa Lucía, Cartagena, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Trujillo-Santos
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schellong
authors.forename: Conxita
authors.initials: C
authors.lastname: Falga
authors.forename: Vanessa
authors.initials: V
authors.lastname: Zorrilla
authors.forename: Pedro
authors.initials: P
authors.lastname: Gallego
authors.forename: Manuel
authors.initials: M
authors.lastname: Barrón
authors.forename: Manuel
authors.initials: M
authors.lastname: Monreal
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006493:Heparin / Q000009:adverse effects / Q000627:therapeutic use*; D006495:Heparin, Low-Molecular-Weight / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D007668:Kidney / Q000187:drug effects* / Q000503:physiopathology; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D051437:Renal Insufficiency / Q000150:complications* / Q000188:drug therapy / Q000401:mortality; D016896:Treatment Outcome; D054556:Venous Thromboembolism / Q000150:complications / Q000188:drug therapy* / Q000401:mortality
chemical_list: D006495:Heparin, Low-Molecular-Weight; D006493:Heparin