Anticoagulation: weight-based algorithm for subcutaneous heparin was useful.

Clinical bottom line (level 4)

  1. A weight-based algorithm for subcutaneous heparin effectively anticoagulated patients within 48 hours.
Prandoni et al: Annals of Internal Medicine 1998; 129 (4): 299-302
Expires June 2003

The study

Case series with objective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.

Setting: outpatients' clinic, university hospital, Italy

70 patients (aged ?, ?% male) symptomatic first episode of proximal DVT (diagnosed on compression ultrasound)

Excluded if
  • on-going full-dose anticoagulation
  • contraindication to anticoagulation
  • pregnant
  • poor life expectancy


    • All patients had heparin bolus iv, followed by subcutaneous heparin using the following algorithm:
    • <50 kg: 4000 IU iv, then 125000 U s/c
    • 50-70 kg: 5000 IU iv, then 15000 U s/c
    • >70 kg: 6000 IU iv, then 17500 U s/c
    • aPTT 120 s or less: no adjustment of heparin dose:
    • aPTT <50 s: heparin dose- one step up: time to next aPTT- after 6 hours
    • aPTT- 50-90 s: heparin dose- same step: time to next aPTT- after 6 hours
    • aPTT- 91-120 s: heparin dose- one step down: time to next aPTT- after 6 hours
    • aPTT- >120 s: heparin dose- withhold heparin, perform aPTT and proceed as follows:
    • aPTT- <50 s: heparin dose- same step: time to next aPTT- after 6 hours
    • aPTT- 50-90 s: heparin dose- one step down: time to next aPTT- after 6 hours
    • aPTT- 91-120 s: heparin dose- two steps down: time to next aPTT- after 6 hours
    • aPTT- >120 s: heparin dose- withhold heparin therapy: time to next aPTT- after 3 hours
    • steps for heparin dose: 10,000-12,500-15,000-17,500-21,250-25,000-30,000


    100% followed for 3 months
    Outcomes studied:
  • therapeutic aPTT at 24 hours
  • therapeutic aPTT at 48 hours
  • recurrent thromboembolism
  • bleeding or heparin-induced thrombocytopenia

    • Patients started warfarin after 1 to 2 days, adjusted so INR 2.0 to 3.0 and continued it for 12 weeks.

    The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    therapeutic aPTT at 24 hours 3 months 61/70 87%
    (79% to 95%)
    therapeutic aPTT at 48 hours 3 months 69/70 99%
    (92.3% to 100%)
    recurrent thromboembolism 3 months 3/70 4.3%
    (0.9% to 12%)
    bleeding or heparin-induced thrombocytopenia 3 months 0/70 0.0%
    (0.0% to 5.1%)

    Comments

    1. Small size and lack of control group makes these results less certain.
    2. LMWH has been shown to be safe and efficacious when given to out-patients. It is also cheaper and more effective than heparin.

    Citation

    1. Prandoni P, Bagatella P, Bernardi E, et al: Use of an algorithm for administering subcutaneous heparin in the treatment of deep venous thrombosis. Annals of Internal Medicine 1998; 129 (4): 299-302
    Search Terms: hand search
    Contributor: Chris Ball and Clare Wotton, June 2000
    Reviewer:

    Clinical Question.
    Patient DVT
    Intervention or Exposure heparin
    Outcome dosing according to algorithm