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Point-of-care testing of the international normalized ratio in patients with antiphospholipid antibodies.

Publication ,  Journal Article
Perry, SL; Samsa, GP; Ortel, TL
Published in: Thromb Haemost
December 2005

Antiphospholipid antibodies can influence the results of clotting tests in a subset of patients, which can be a major obstacle in monitoring warfarin. The aim was to determine if point-of-care testing of the International Normalized Ratio (INR) is influenced by antiphospholipid antibodies. We compared 59 patients receiving warfarin for a diagnosis of antiphospholipid antibody syndrome (APS) to 49 patients receiving warfarin for atrial fibrillation to evaluate the consistency between INR results obtained by different methods. INR results obtained by finger stick (capillary whole-blood) and venipuncture (non-citrated and citrated whole-blood) were compared with our laboratory plasma-based prothrombin time assay. Five patients (8%) with APS and both elevated anti-beta2glycoprotein I levels and positive lupus anticoagulants had non-measurable ProTime INR results and generally higher Hemochron Signature INR results than the plasma-based method, but the corresponding chromogenic factor X results were not supratherapeutic. For the remaining patients, differences between the plasma-based INR and the point-of-care INR results ranged from 0.2 +/- 0.2 to 0.4 +/- 0.3. The differences were similar for patients with APS and atrial fibrillation for all INR comparisons with the exception of the plasma-based method compared with the ProTime, which showed a mean absolute difference of 0.4 +/- 0.3 for APS patients and of 0.2 +/- 0.2 for atrial fibrillation patients (p = 0.02). In a subset ofAPS patients, the ProTime system will not yield an INR result and the HEMochron Signature (citrate and non-citrate whole-blood) INR results will exhibit elevated INR results. For this subset of APS patients, we suggest using an alternative method to monitor warfarin.

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Published In

Thromb Haemost

DOI

ISSN

0340-6245

Publication Date

December 2005

Volume

94

Issue

6

Start / End Page

1196 / 1202

Location

Germany

Related Subject Headings

  • Warfarin
  • Reproducibility of Results
  • Prothrombin Time
  • Point-of-Care Systems
  • Middle Aged
  • Male
  • International Normalized Ratio
  • Humans
  • Female
  • Drug Monitoring
 

Citation

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ICMJE
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Perry, S. L., Samsa, G. P., & Ortel, T. L. (2005). Point-of-care testing of the international normalized ratio in patients with antiphospholipid antibodies. Thromb Haemost, 94(6), 1196–1202. https://doi.org/10.1160/TH05-06-0400
Perry, Stephanie L., Gregory P. Samsa, and Thomas L. Ortel. “Point-of-care testing of the international normalized ratio in patients with antiphospholipid antibodies.Thromb Haemost 94, no. 6 (December 2005): 1196–1202. https://doi.org/10.1160/TH05-06-0400.
Perry SL, Samsa GP, Ortel TL. Point-of-care testing of the international normalized ratio in patients with antiphospholipid antibodies. Thromb Haemost. 2005 Dec;94(6):1196–202.
Perry, Stephanie L., et al. “Point-of-care testing of the international normalized ratio in patients with antiphospholipid antibodies.Thromb Haemost, vol. 94, no. 6, Dec. 2005, pp. 1196–202. Pubmed, doi:10.1160/TH05-06-0400.
Perry SL, Samsa GP, Ortel TL. Point-of-care testing of the international normalized ratio in patients with antiphospholipid antibodies. Thromb Haemost. 2005 Dec;94(6):1196–1202.
Journal cover image

Published In

Thromb Haemost

DOI

ISSN

0340-6245

Publication Date

December 2005

Volume

94

Issue

6

Start / End Page

1196 / 1202

Location

Germany

Related Subject Headings

  • Warfarin
  • Reproducibility of Results
  • Prothrombin Time
  • Point-of-Care Systems
  • Middle Aged
  • Male
  • International Normalized Ratio
  • Humans
  • Female
  • Drug Monitoring