Assessing the Ability of Warfarin Treated Patients to Predict Their INR

ASSESSING THE ABILITY OF WARFARIN TREATED PATIENTS TO PREDICT THEIR INR Kathleen McNamara, James Hoehns, Matthew Witry

The international normalized ratio (INR) is the accepted lab test used to measure the intensity of warfarin effect. The conventional wisdom is that patients receiving warfarin are unable to correctly determine, in the absence of an INR result, whether or not they are therapeutic at any given time. Some warfarin treated patients express that they have insight into what their INR result will be. Various patient related factors may contribute to these opinions.

Our objective is to assess how accurately patients can guess their INR result before it is obtained and to describe factors which inform their opinion of what their INR will be.

Study Overview

• Status: Completed
• Conditions: Atrial Fibrillation

Detailed Description

ASSESSING THE ABILITY OF WARFARIN TREATED PATIENTS TO PREDICT THEIR INR Kathleen McNamara, James Hoehns, Matthew Witry

The international normalized ratio (INR) is the accepted lab test used to measure the intensity of warfarin effect. The conventional wisdom is that patients receiving warfarin are unable to correctly determine, in the absence of an INR result, whether or not they are therapeutic at any given time. Some warfarin treated patients express that they have insight into what their INR result will be. Various patient related factors may contribute to these opinions.

Our objective is to assess how accurately patients can guess their INR result before it is obtained and to describe factors which inform their opinion of what their INR will be. In this prospective study, the investigators will enroll warfarin treated patients from 7 anticoagulation clinics in Iowa. Inclusion criteria are: age ≥18 years, warfarin use ≥60 days, INR goal of 2.0-3.0 or 2.5-3.5, expected warfarin use >6 months, and English speaking. Exclusion criteria include: use of self INR-testing, home INR draws, dementia, or residing in a long-term care facility. A data collection form will be completed prior to INR measurement for a 6 month period. Information will be collected for subject demographics, warfarin adherence, INR stability, INR prediction, and prediction rationale.

INR monitoring represents a significant burden with respect to cost and time. The results of this study may identify patient factors which could help individualize and decrease the frequency of INR monitoring in patients who receive maintenance warfarin therapy.

• Study Type: Observational
• Enrollment (Actual): 87

Contacts and Locations

Study Locations

• United States
  • Iowa
    • Waterloo, Iowa, United States, 50702
      • Northeast Iowa Family Practice

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

In this prospective study, we will enroll warfarin treated patients from 8 anticoagulation clinics in Iowa. Inclusion criteria are: age ≥18 years, warfarin use ≥60 days, INR goal of 2.0-3.0 or 2.5-3.5, expected warfarin use >6 months, and English speaking. Exclusion criteria include: use of self INR-testing, home INR draws, dementia, or residing in a long-term care facility.

Description

Inclusion Criteria:

• Age ≥18 years
• Warfarin use ≥60 days
• INR goal of 2.0-3.0 or 2.5-3.5
• Expected warfarin use >6 months
• English speaking

Exclusion Criteria:

• Self INR-testing
• Home INR draws
• Dementia
• Residence of a long-term care facility

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Assess factors which influence INR predictions	Patients will be asked to predict their INR value prior to having it tested. We will record patient's INR prediction and the value we obtain after testing INR.	6 months

Collaborators and Investigators

• Sponsor: Northeast Iowa Medical Education Foundation
• Collaborators: University of Iowa

Publications and helpful links

General Publications

• McNamara K, Witry M, Bryant G, Koenigsfeld C, Lehman N, Logemann C, Mormann M, Rueber A, Herring M, Hoehns JD. A prospective, multi-center cohort study: investigating the ability of warfarin-treated patients to predict their INR. Clin Res Cardiol. 2019 Feb;108(2):212-217. doi: 10.1007/s00392-018-1345-9. Epub 2018 Aug 8.

Study record dates

Study Major Dates

• Study Start: October 1, 2015
• Primary Completion (Actual): July 1, 2016
• Study Completion (Actual): July 1, 2016

Study Registration Dates

• First Submitted: March 30, 2016
• First Submitted That Met QC Criteria: May 3, 2016
• First Posted (Estimate): May 6, 2016

Study Record Updates

• Last Update Posted (Actual): June 27, 2019
• Last Update Submitted That Met QC Criteria: June 25, 2019
• Last Verified: June 1, 2019

More Information

Terms related to this study

• Keywords: warfarin
• Additional Relevant MeSH Terms: Pathologic Processes; Heart Diseases; Cardiovascular Diseases; Arrhythmias, Cardiac; Atrial Fibrillation
• Other Study ID Numbers: 914 (Northumbria University)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO