Current dosing of low-molecular-weight heparins does not reflect licensed product labels: an international survey

Authors

  • Michael A. Barras,

    1. School of Pharmacy, The University of Queensland, Brisbane, Queensland,
    2. Therapeutic Advisory Service, Pharmacy Department, Mater Health Services, Brisbane, Queensland, and
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  • Carl M. J. Kirkpatrick,

    1. Therapeutic Advisory Service, Pharmacy Department, Mater Health Services, Brisbane, Queensland, and
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  • Bruce Green

    Corresponding author
    1. Model Answers Pty Ltd, Brisbane, Queensland, Australia
      Dr Bruce Green, Model Answers Pty Ltd, Brisbane, Queensland 4171, Australia.
      Tel.: + 61 421 668 445
      Fax: +61 738 991 553
      E-mail: modelanswers@gmail.com
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Dr Bruce Green, Model Answers Pty Ltd, Brisbane, Queensland 4171, Australia.
Tel.: + 61 421 668 445
Fax: +61 738 991 553
E-mail: modelanswers@gmail.com

Abstract

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Low-molecular-weight heparins (LMWHs) are effective anti-coagulants for the treatment of thromboembolic diseases.

• LMWHs are hydrophilic drugs with clearance related to lean body weight and renal function.

• Poor subject outcomes are linked to the inadequate dosing of LMWHs.

WHAT THIS STUDY ADDS

• Minimal adherence to the product label occured when dosing LMWHs.

• Hospitals preferred to dose-individualize using a variety of methods that included dose-capping, post-dose monitoring of anti-Xa activity and the use of lean body size descriptors to calculate a starting dose and renal function.

AIMS Low-molecular-weight heparins (LMWHs) are used globally to treat thromboembolic diseases; however, there is much debate on how to prescribe effectively for patients who have renal impairment and/or obesity. We aimed to investigate the strategies used to dose-individualize LMWH therapy.

METHODS We conducted an online survey of selected hospitals in Australia, New Zealand (NZ), United Kingdom (UK) and the United States (US). Outcome measures included: the percentage of hospitals which recommended that LMWHs were prescribed according to the product label (PL), the percentage of hospitals that dose-individualized LMWHs outside the PL based on renal function, body weight and anti-Xa activity and a summary of methods used to dose-individualize therapy.

RESULTS A total of 257 surveys were suitable for analysis: 84 (33%) from Australia, 79 (31%) from the UK, 73 (28%) from the US and 21 (8%) from NZ. Formal dosing protocols were used in 207 (81%) hospitals, of which 198 (96%) did not adhere to the PL. Of these 198 hospitals, 175 (87%) preferred to dose-individualize based on renal function, 128 (62%) on body weight and 48 (23%) by monitoring anti-Xa activity. All three of these variables were used in 29 (14%) hospitals, 98 (47%) used two variables and 71 (34%) used only one variable.

CONCLUSIONS Dose-individualization strategies for LMWHs, which contravene the PL, were present in 96% of surveyed hospitals. Common individualization methods included dose-capping, use of lean body size descriptors to calculate renal function and the starting dose, followed by post dose anti-Xa monitoring.

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