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

NCT00878137 | Completed

• 1 other identifier: POC Comparison 08-1883
• Study Type: observational
• Target: 63
• Locations: 1 country
• Sites: 1

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.

Conditions

Antiphospholipid Syndrome

Study Arms (2)

APLA

Patients with antiphospholipid antibody syndrome.

Device: INR by point-of-care instruments and venopuncture

Control

Patients on warfarin therapy but without antiphosphilipid antibody syndrome.

Device: INR by point-of-care instruments and venopuncture

Interventions

INR by point-of-care instruments and venopuncture DEVICE

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; Control

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• 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.

You may qualify if:

• 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.

You may not qualify if:

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

Sponsors & Collaborators

• University of North Carolina, Chapel Hill: lead
• International Technidyne Corporation: collaborator

Study Sites (1)

University of North Carolina at Chapel Hill

Chapel Hill, North Carolina, 27514, United States

Location

MeSH Terms

Conditions

Antiphospholipid Syndrome

Condition Hierarchy (Ancestors)

Autoimmune Diseases; Immune System Diseases

Study Officials

• Lauren B McKnight, PharmD

  University of North Carolina, Chapel Hill

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: CASE CONTROL
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Clinical Pharmacist

Study Record Dates

• First Submitted: April 6, 2009
• First Posted: April 8, 2009
• Study Start: March 1, 2009
• Primary Completion: May 1, 2009
• Study Completion: May 1, 2009
• Last Updated: October 15, 2012

Record last verified: 2012-10

Locations

US (1)