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

Study Description

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Brief Summary:

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.

Condition or disease	Intervention/treatment
Antiphospholipid Syndrome	Device: INR by point-of-care instruments and venopuncture

Study Design

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Study Type :	Observational
Actual Enrollment :	63 participants
Observational Model:	Case Control
Time Perspective:	Prospective
Official Title:	INR Determined by Plasma-based Methods Versus Newer Point-of-care Instruments in Patients With Antiphospholipid-antibody Syndrome Treated With Anticoagulants
Study Start Date :	March 2009
Actual Primary Completion Date :	May 2009
Actual Study Completion Date :	May 2009

Groups and Cohorts

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Study Description Study Design Groups and Cohorts Outcome Measures Eligibility Criteria Contacts and Locations More Information

Group/Cohort	Intervention/treatment
APLA; Patients with antiphospholipid antibody 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.
Control; Patients on warfarin therapy but without antiphosphilipid antibody 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.

Outcome Measures

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Study Description Study Design Groups and Cohorts Outcome Measures Eligibility Criteria Contacts and Locations More Information

Eligibility Criteria

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Study Description Study Design Groups and Cohorts Outcome Measures Eligibility Criteria Contacts and Locations More Information

Ages Eligible for Study:	18 Years and older (Adult, Senior)
Sexes Eligible for Study:	All
Accepts Healthy Volunteers:	No
Sampling Method:	Non-Probability Sample

Study Population

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

Criteria

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.

Contacts and Locations

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Study Description Study Design Groups and Cohorts Outcome Measures Eligibility Criteria Contacts and Locations More Information

Locations

United States, North Carolina
University of North Carolina at Chapel Hill
Chapel Hill, North Carolina, United States, 27514

Sponsors and Collaborators

University of North Carolina, Chapel Hill

International Technidyne Corporation

Investigators

Principal Investigator:	Lauren B McKnight, PharmD	University of North Carolina, Chapel Hill

More Information

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Study Description Study Design Groups and Cohorts Outcome Measures Eligibility Criteria Contacts and Locations More Information

Responsible Party:	Lauren McKnight, PharmD, CPP, Clinical Pharmacist, University of North Carolina, Chapel Hill
ClinicalTrials.gov Identifier:	NCT00878137 History of Changes
Other Study ID Numbers:	POC Comparison 08-1883
First Posted:	April 8, 2009
Last Update Posted:	October 15, 2012
Last Verified:	October 2012

Additional relevant MeSH terms:

Syndrome; Antiphospholipid Syndrome; Antibodies, Antiphospholipid; Disease; Pathologic Processes; Autoimmune Diseases; Immune System Diseases	Antibodies; Immunoglobulins; Warfarin; Immunologic Factors; Physiological Effects of Drugs; Anticoagulants