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

Purpose

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	Intervention
Antiphospholipid Syndrome	Device: INR by point-of-care instruments and venopuncture


Study Type:	Observational
Study Design:	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

Resource links provided by NLM:

Genetics Home Reference related topics: antiphospholipid syndrome

MedlinePlus related topics: Blood Thinners

Genetic and Rare Diseases Information Center resources: Antiphospholipid Syndrome

U.S. FDA Resources

Further study details as provided by Lauren McKnight, PharmD, CPP, University of North Carolina, Chapel Hill:


Enrollment:	63
Study Start Date:	March 2009
Study Completion Date:	May 2009
Primary Completion Date:	May 2009 (Final data collection date for primary outcome measure)

Groups/Cohorts	Assigned Interventions
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.

Groups/Cohorts

Assigned Interventions

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.

Eligibility


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

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00878137

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


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
Study First Received:	April 6, 2009
Last Updated:	October 12, 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

ClinicalTrials.gov processed this record on June 26, 2017