Journal of General Internal Medicine

, Volume 26, Issue 5, pp 487–491 | Cite as

Dosing of Unfractionated Heparin in Obese Patients with Venous Thromboembolism

  • Adam N. HurewitzEmail author
  • Samar U. Khan
  • Maritza L. Groth
  • Patricia A. Patrick
  • Donald A. Brand
Original Research



Aggressive weight-based dosing guidelines help achieve prompt therapeutic anticoagulation in patients with venous thromboembolism (VTE). While obese patients with VTE face an increased risk of recurrence, physicians typically resist prescribing doses two to three times the usual dose because of concern about bleeding complications.


To examine the use of unfractionated heparin in obese patients with VTE at an academic teaching hospital in order to document the extent and pattern of underprescribing in this high-risk patient population.


Three-year, cross-sectional consecutive case series.


Adult inpatients with VTE and a body mass index ≥30 kg/m2 who were treated with unfractionated heparin.


Time to achievement of therapeutic anticoagulation (activated partial thromboplastin time >60 s) and gap between recommended and prescribed heparin doses.


Time to attainment of therapeutic anticoagulation exceeded 24 h in 29% of study patients (n = 84) and exceeded 48 h in 14% of patients. In 75 patients (89%), the prescribed bolus dose fell below the recommended dose of 80 units/kg, and in 64 patients (76%) the initial continuous infusion fell more than 100 units/h below—in some cases more than 1000 units/h below—the recommended dose of 18 units/kg/h. There was a significant correlation between time to therapeutic anticoagulation and initial infusion dose (Spearman r = –0.27; p < 0.02). Each decrease of 1 unit/kg/h translated to a delay ranging from about 0.75 h to 1.5 h over the range of prescribed doses (6 to 22 units/kg/h).


A substantial proportion of obese patients treated with unfractionated heparin experienced a delay >24 h in achieving adequate anticoagulation, and the vast majority received an inadequate heparin bolus or initial continuous infusion (or both) according to current dosing guidelines.


anticoagulants/administration & dosage body weight heparin/therapeutic use obesity thromboembolism/drug therapy 



We thank Henian Chen, M.D., Ph.D. and Martin Feuerman, M.S., for advice about the statistical analysis.



Prior Presentations


Conflict of Interest

None disclosed.


  1. 1.
    Heit JA, Silverstein MD, Mohr DN, et al. The epidemiology of venous thromboembolism in the community. Thromb Haemost. 2001;86:452–63.PubMedGoogle Scholar
  2. 2.
    Eichinger S, Hron G, Bialonczyk C, et al. Overweight, obesity, and the risk of recurrent venous thromboembolism. Arch Intern Med. 2008;168:1678–83.PubMedCrossRefGoogle Scholar
  3. 3.
    Raschke RA, Reilly BM, Guidry JR, Fontana JR, Srinivas S. The weight-based heparin dosing nomogram compared with a "standard care" nomogram. A randomized controlled trial. Ann Intern Med. 1993;119:874–81.PubMedGoogle Scholar
  4. 4.
    Hull RD, Raskob GE, Rosenbloom D, et al. Optimal therapeutic level of heparin therapy in patients with venous thrombosis. Arch Intern Med. 1992;152:1589–95.PubMedCrossRefGoogle Scholar
  5. 5.
    Hirsh J, Bauer KA, Donati MB, Gould M, Samama MM, Weitz JI. Parenteral anticoagulants. ACCP Evidence-Based Clinical Practice Guidelines (8th ed). Chest. 2008;133:141s–59s.PubMedCrossRefGoogle Scholar
  6. 6.
    Wheeler AP, Jaquiss RD, Newman JH. Physician practices in the treatment of pulmonary embolism and deep venous thrombosis. Arch Intern Med. 1988;148:1321–5.PubMedCrossRefGoogle Scholar
  7. 7.
    Pollack CV Jr, Braunwald E. 2007 update to the ACC/AHA guidelines for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction: implications for emergency department practice. Ann Emerg Med. 2008;51:591–606.PubMedCrossRefGoogle Scholar
  8. 8.
    Hull RD, Raskob GE, Brant RF, Pineo GF, Valentine KA. Relation between the time to achieve the lower limit of the APTT therapeutic range and recurrent venous thromboembolism during heparin treatment for deep vein thrombosis. Arch Intern Med. 1997;157:2562–8.PubMedCrossRefGoogle Scholar
  9. 9.
    Bernardi E, Piccioli A, Oliboni G, Zuin R, Girolami A, Prandoni P. Nomograms for the administration of unfractionated heparin in the initial treatment of acute thromboembolism—an overview. Thromb Haemost. 2000;84:22–6.PubMedGoogle Scholar
  10. 10.
    Davidson BL, Büller HR, Decousus H, et al. Effect of obesity on outcomes after fondaparinux, enoxaparin, or heparin treatment for acute venous thromboembolism in the Matisse trials. J Thromb Haemost. 2007;5:1191–4.PubMedCrossRefGoogle Scholar
  11. 11.
    Barba R, Zapatero A, Losa JE, et al. Body mass index and mortality in patients with acute venous thromboembolism: findings from the RIETE registry. J Thromb Haemost. 2008;6:595–600.PubMedCrossRefGoogle Scholar
  12. 12.
    Stein PD, Beemath A, Olson RE. Obesity as a risk factor in venous thromboembolism. Am J Med. 2005;118:978–80.PubMedCrossRefGoogle Scholar
  13. 13.
    Caprini JA, Tapson VF, Hyers TM, et al. Treatment of venous thromboembolism: adherence to guidelines and impact of physician knowledge, attitudes, and beliefs. J Vasc Surg. 2005;42:726–33.PubMedCrossRefGoogle Scholar
  14. 14.
    Hylek EM, Regan S, Henault LE, Gardner M, Chan AT, Singer DE, Barry MJ. Challenges to the effective use of unfractionated heparin in the hospitalized management of acute thrombosis. Arch Intern Med. 2003;163:621–7.PubMedCrossRefGoogle Scholar

Copyright information

© Society of General Internal Medicine 2010

Authors and Affiliations

  • Adam N. Hurewitz
    • 1
    Email author
  • Samar U. Khan
    • 2
  • Maritza L. Groth
    • 1
  • Patricia A. Patrick
    • 3
  • Donald A. Brand
    • 3
    • 4
  1. 1.Pulmonary and Critical Care MedicineWinthrop University HospitalMineolaUSA
  2. 2.Pulmonary and Critical Care Medicine, Vassar Brothers Medical CenterPoughkeepsieUSA
  3. 3.Office of Health Outcomes ResearchWinthrop University HospitalMineolaUSA
  4. 4.Department of Preventive MedicineStony Brook University School of MedicineStony BrookUSA

Personalised recommendations