title: Venous thromboembolism prophylaxis in hospitalized medical patients and those with stroke: a background review for an American College of Physicians Clinical Practice Guideline.
abstract: BACKGROUND
  Venous thromboembolism prophylaxis has been recommended for nonsurgical patients, but its effectiveness remains uncertain.
  
  
  OBJECTIVE
  To assess the benefits and harms of prophylaxis in hospitalized adult medical patients and those with acute stroke.
  
  
  METHODS
  MEDLINE and the Cochrane Library from 1950 through April 2011, reference lists, and study authors.
  
  
  METHODS
  English-language randomized trials were included if they provided clinical outcomes and evaluated therapy with low-dose heparin or related agents or mechanical measures compared with placebo, no treatment, or other active prophylaxis in the target population.
  
  
  METHODS
  Two independent investigators extracted data on study characteristics and clinical outcomes up to 120 days after randomization. The primary outcome was total mortality.
  
  
  RESULTS
  In medical patients, heparin prophylaxis did not reduce total mortality but did result in fewer pulmonary embolisms (PEs) (odds ratio [OR], 0.69 [95% CI, 0.52 to 0.90], but with evidence of publication bias) and an increase in all bleeding events (risk ratio [RR], 1.34 [CI, 1.08 to 1.66]). Heparin prophylaxis had no statistically significant effect on any outcome in patients with acute stroke except for an increase in major bleeding events (OR, 1.66 [CI, 1.20 to 2.28]). When trials of medical patients and those with stroke were considered together (18 studies; 36,122 patients), heparin prophylaxis reduced the incidence of PE (OR, 0.70 [CI, 0.56 to 0.87]; absolute reduction, 3 events per 1000 patients treated [CI, 1 to 5 events]) but increased the incidence of all bleeding (RR, 1.28 [CI, 1.05 to 1.56]) and major bleeding events (OR, 1.61 [CI, 1.23 to 2.10]), with an absolute increase of 9 bleeding events per 1000 patients treated (CI, 2 to 18 events), 4 of which were major (CI, 1 to 7 events). A reduction in total mortality approached statistical significance (RR, 0.93 [CI, 0.86 to 1.00]; P = 0.056; absolute decrease, 6 deaths per 1000 patients treated [CI, 0 to 11 deaths]). No statistically significant differences in clinical outcomes were observed in the 14 trials that compared unfractionated heparin with low-molecular-weight heparin. No improvements in clinical outcomes were seen in the 3 studies of mechanical prophylaxis in patients with stroke, but more patients had lower-extremity skin damage (RR, 4.02 [CI, 2.34 to 6.91])-an increase of 39 events per 1000 patients treated (CI, 17 to 77 events).
  
  
  CONCLUSIONS
  Non-English-language studies were not included, but these were few and small.
  
  
  CONCLUSIONS
  Heparin prophylaxis had no significant effect on mortality, may have reduced PE in medical patients and all patients combined, and led to more bleeding and major bleeding events, thus resulting in little or no net benefit. No differences in benefits or harms were found according to type of heparin used. Mechanical prophylaxis provided no benefit and resulted in clinically important harm to patients with stroke.
  
  
  BACKGROUND
  American College of Physicians.
authors: Minnesota Evidence-based Practice Center, Minneapolis Veterans Affairs Medical Center, Minnesota, USA. frank.lederle@va.gov
authors: Frank A
authors: FA
authors: Lederle
authors: Dylan
authors: D
authors: Zylla
authors: Roderick
authors: R
authors: MacDonald
authors: Timothy J
authors: TJ
authors: Wilt
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D057186:Comparative Effectiveness Research; D006470:Hemorrhage / Q000139:chemically induced; D006493:Heparin / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D017052:Hospital Mortality; D006760:Hospitalization; D006801:Humans; D016017:Odds Ratio; D017594:Publication Bias; D011655:Pulmonary Embolism / Q000401:mortality / Q000517:prevention & control; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D053828:Stockings, Compression; D020521:Stroke / Q000150:complications*; D054556:Venous Thromboembolism / Q000517:prevention & control*
chemical_list: D000925:Anticoagulants; D006493:Heparin