Reliability of Point-of-care INR Measurements in Patients With Antiphospholipid-antibody Syndrome Treated With Warfarin

This study has been completed.
Sponsor:
Collaborator:
International Technidyne Corporation
Information provided by (Responsible Party):
Lauren McKnight, PharmD, CPP, University of North Carolina, Chapel Hill
ClinicalTrials.gov Identifier:
NCT00878137
First received: April 6, 2009
Last updated: October 12, 2012
Last verified: October 2012

April 6, 2009
October 12, 2012
March 2009
May 2009   (final data collection date for primary outcome measure)
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Complete list of historical versions of study NCT00878137 on ClinicalTrials.gov Archive Site
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Reliability of Point-of-care INR Measurements in Patients With Antiphospholipid-antibody Syndrome Treated With Warfarin
INR Determined by Plasma-based Methods Versus Newer Point-of-care Instruments in Patients With Antiphospholipid-antibody Syndrome Treated With Anticoagulants

The antiphospholipid-antibody syndrome (APLA), which includes lupus anticoagulant, anticardiolipin, and anti-beta-2-glycoproteinI antibodies, is a thrombophilic disorder associated with arterial thrombosis, venous thrombosis or both. Patients diagnosed with APLA have a higher risk of recurrent thrombosis than do patients without known antibodies. Currently, warfarin is considered the anticoagulant of choice for prophylactic antithrombotic treatment for APLA patients after their first episode of thrombosis. In some patients with APLA who are treated with warfarin, the INR values determined on plasma are unreliable due to an influence of the APLA on the INR. In these individuals, alternative monitoring methods, such as factor II activity, chromogenic factor X activity or prothrombin-proconvertin time should be used to assess adequate anticoagulation. These tests are expensive and not widely available to some clinicians. Point-of-care (POC) instruments, on the other hand, are readily accessible to clinicians. Previous research has shown that INR values from 3 older point-of-care (POC) instruments are unreliable in 1/3 of APLA patients (CoaguChekTM, ProTimeTM, INRatioTM). However, there are now newer versions of these POC instruments available (CoaguChek XSTM, an investigational ProTime device, and a newer INRatioTM device) and it is unknown if these newer POC instruments are reliable in patients with APLA. The purpose of this study is to determine whether newer POC instruments are reliable in patients with APLA.

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Observational
Observational Model: Case Control
Time Perspective: Prospective
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Non-Probability Sample

APLA patients will be identified through the UNC Thrombophilia Program database. Control patients will be recruited at UNC Anticoagulation Clinic visits.

Antiphospholipid Syndrome
Device: INR by point-of-care instruments and venopuncture
Three fingersticks will be performed and from each one drop of capillary or venous whole blood collected from a fingerstick performed by the primary investigator to measure PT/INR using the CoaguChekXSTM (10 microliters), ProTimeTM (27 microliters), the investigational ProTime, and INRatioTM 15 microliters) point-of-care instruments and one i.v. blood draw (20 mL of blood) will be performed by a phlebotomist.
  • APLA
    Patients with antiphospholipid antibody syndrome.
    Intervention: Device: INR by point-of-care instruments and venopuncture
  • Control
    Patients on warfarin therapy but without antiphosphilipid antibody syndrome.
    Intervention: Device: INR by point-of-care instruments and venopuncture
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*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Completed
63
May 2009
May 2009   (final data collection date for primary outcome measure)

APLA Inclusion Criteria:

  • Prolongation of a phospholipid-dependent screening assay, 2) lack of correction of a prolonged screening assay after a 1:1 mix with pooled normal plasma, and 3) correction of a prolonged screening assay by the addition of excess phospholipid. Two positive lupus anticoagulant confirmations at least 3 months apart will be required.
  • Diagnosis of anticardiolipin antibodies defined as elevated levels of ACA-IgG (>30) and/or ACA-IgM (>15) on two separate occasions at least 3 months apart.
  • Stable warfarin therapy, defined as the maintenance of a warfarin dose for a minimal of 2 weeks regardless of INR.

APLA Exclusion Criteria:

  • Patients whose warfarin dose has changed within the past 2 weeks.

Control Inclusion Criteria:

  • No evidence of either a positive LA or ACA diagnosis by confirmation of negative laboratory values and/or documentation of no clinical signs and symptoms concurrent with these conditions.
  • Stable warfarin therapy, defined as the maintenance of a warfarin dose for a minimal of 2 weeks regardless of INR.

Control Exclusion Criteria:

  • Patients whose warfarin dose has changed within the past 2 weeks.
Both
18 Years and older
No
Contact information is only displayed when the study is recruiting subjects
United States
 
NCT00878137
POC Comparison 08-1883
No
Lauren McKnight, PharmD, CPP, University of North Carolina, Chapel Hill
University of North Carolina, Chapel Hill
International Technidyne Corporation
Principal Investigator: Lauren B McKnight, PharmD University of North Carolina, Chapel Hill
University of North Carolina, Chapel Hill
October 2012

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP