Monitoring anticoagulation in patients with an unreliable prothrombin time/international normalized ratio

Factor II versus chromogenic factor X testing

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6 Citations (Scopus)

Abstract

The international normalized ratio (INR) can be unreliable in patients with lupus anticoagulants (LACs) or other conditions affecting baseline testing. Alternative methods to assess anticoagulation on warfarin through measures of vitamin K-dependent factor activity by clot based or chromogenic assays may be necessary. In this patient population, the ideal method is unknown. Thirty-six patients stable on warfarin with LAC or unreliable INR testing had an INR, a prothrombin time-based clotting assay for factor II (FII) activity, and a chromogenic assay for factor X (CFX) activity were performed simultaneously. Eighty-nine sets of measurements were obtained of which 83 sets included all three assays. CFX and FII levels were well correlated (r=0.92) in all patients and in 26 patients with a documented antiphospholipid antibody (r=0.93). Parallel testing was seen in 99% of FII assays. Sixty-one percent of CFX and 57% of FII were within the therapeutic range. In 32 CFX and FII pairs wherein assessment of anticoagulation was discordant, 16 CFX agreed with INR and 13 FII agreed with INR (McNemar's, χ=0.14, P=0.7). The number of times tests were discrepant was not statistically different between CFX and FII (P=0.36). CFX and FII activity are well correlated in patients that require alternative monitoring of warfarin. Either test can be used in this population.

Original languageEnglish (US)
Pages (from-to)232-236
Number of pages5
JournalBlood Coagulation and Fibrinolysis
Volume25
Issue number3
DOIs
StatePublished - Jan 1 2014

Fingerprint

Factor X
International Normalized Ratio
Prothrombin Time
Prothrombin
Warfarin
Lupus Coagulation Inhibitor
Antiphospholipid Antibodies
Blood Coagulation Factors
Vitamin K
Population
hexachlorocyclohexane x-factor

Keywords

  • Anticoagulation
  • Antiphospholipid antibody syndrome
  • Chromogenic factor X
  • Factor II
  • Warfarin

Cite this

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title = "Monitoring anticoagulation in patients with an unreliable prothrombin time/international normalized ratio: Factor II versus chromogenic factor X testing",
abstract = "The international normalized ratio (INR) can be unreliable in patients with lupus anticoagulants (LACs) or other conditions affecting baseline testing. Alternative methods to assess anticoagulation on warfarin through measures of vitamin K-dependent factor activity by clot based or chromogenic assays may be necessary. In this patient population, the ideal method is unknown. Thirty-six patients stable on warfarin with LAC or unreliable INR testing had an INR, a prothrombin time-based clotting assay for factor II (FII) activity, and a chromogenic assay for factor X (CFX) activity were performed simultaneously. Eighty-nine sets of measurements were obtained of which 83 sets included all three assays. CFX and FII levels were well correlated (r=0.92) in all patients and in 26 patients with a documented antiphospholipid antibody (r=0.93). Parallel testing was seen in 99{\%} of FII assays. Sixty-one percent of CFX and 57{\%} of FII were within the therapeutic range. In 32 CFX and FII pairs wherein assessment of anticoagulation was discordant, 16 CFX agreed with INR and 13 FII agreed with INR (McNemar's, χ=0.14, P=0.7). The number of times tests were discrepant was not statistically different between CFX and FII (P=0.36). CFX and FII activity are well correlated in patients that require alternative monitoring of warfarin. Either test can be used in this population.",
keywords = "Anticoagulation, Antiphospholipid antibody syndrome, Chromogenic factor X, Factor II, Warfarin",
author = "{Baumann Kreuziger}, {Lisa M.} and Datta, {Yvonne H} and Johnson, {Andrew D} and Zantek, {Nicole D} and Shanley, {Ryan M} and Reding, {Mark T}",
year = "2014",
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T1 - Monitoring anticoagulation in patients with an unreliable prothrombin time/international normalized ratio

T2 - Factor II versus chromogenic factor X testing

AU - Baumann Kreuziger, Lisa M.

AU - Datta, Yvonne H

AU - Johnson, Andrew D

AU - Zantek, Nicole D

AU - Shanley, Ryan M

AU - Reding, Mark T

PY - 2014/1/1

Y1 - 2014/1/1

N2 - The international normalized ratio (INR) can be unreliable in patients with lupus anticoagulants (LACs) or other conditions affecting baseline testing. Alternative methods to assess anticoagulation on warfarin through measures of vitamin K-dependent factor activity by clot based or chromogenic assays may be necessary. In this patient population, the ideal method is unknown. Thirty-six patients stable on warfarin with LAC or unreliable INR testing had an INR, a prothrombin time-based clotting assay for factor II (FII) activity, and a chromogenic assay for factor X (CFX) activity were performed simultaneously. Eighty-nine sets of measurements were obtained of which 83 sets included all three assays. CFX and FII levels were well correlated (r=0.92) in all patients and in 26 patients with a documented antiphospholipid antibody (r=0.93). Parallel testing was seen in 99% of FII assays. Sixty-one percent of CFX and 57% of FII were within the therapeutic range. In 32 CFX and FII pairs wherein assessment of anticoagulation was discordant, 16 CFX agreed with INR and 13 FII agreed with INR (McNemar's, χ=0.14, P=0.7). The number of times tests were discrepant was not statistically different between CFX and FII (P=0.36). CFX and FII activity are well correlated in patients that require alternative monitoring of warfarin. Either test can be used in this population.

AB - The international normalized ratio (INR) can be unreliable in patients with lupus anticoagulants (LACs) or other conditions affecting baseline testing. Alternative methods to assess anticoagulation on warfarin through measures of vitamin K-dependent factor activity by clot based or chromogenic assays may be necessary. In this patient population, the ideal method is unknown. Thirty-six patients stable on warfarin with LAC or unreliable INR testing had an INR, a prothrombin time-based clotting assay for factor II (FII) activity, and a chromogenic assay for factor X (CFX) activity were performed simultaneously. Eighty-nine sets of measurements were obtained of which 83 sets included all three assays. CFX and FII levels were well correlated (r=0.92) in all patients and in 26 patients with a documented antiphospholipid antibody (r=0.93). Parallel testing was seen in 99% of FII assays. Sixty-one percent of CFX and 57% of FII were within the therapeutic range. In 32 CFX and FII pairs wherein assessment of anticoagulation was discordant, 16 CFX agreed with INR and 13 FII agreed with INR (McNemar's, χ=0.14, P=0.7). The number of times tests were discrepant was not statistically different between CFX and FII (P=0.36). CFX and FII activity are well correlated in patients that require alternative monitoring of warfarin. Either test can be used in this population.

KW - Anticoagulation

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KW - Chromogenic factor X

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