The Home INR Study - THINRS — Presented at AHA 2008


The goal of the trial was to evaluate home international normalized ratio (INR) testing.


Home INR testing would be a safe alternative to conventional testing.

Study Design

Study Design:

Patients Screened: 3,644
Patients Enrolled: 2,922
Mean Follow Up: 4.5 years
Mean Patient Age: 67 years
Female: 2

Patient Populations:

  • Patients with atrial fibrillation or a mechanical heart valve treated with warfarin who are capable of performing self INR testing

Primary Endpoints:

  • Time to first major event (death, stroke, or major bleeding)

Secondary Endpoints:

  • Time in target range
  • Satisfaction with anticoagulation
  • Quality of life

Drug/Procedures Used:

Patients were randomized to patient self INR testing (n = 1,465) versus conventional monthly INR testing (n = 1,457).

Principal Findings:

Overall, 2,922 patients were randomized. The mean age of participants was 67 years and there were 98% men. The indication for anticoagulation was atrial fibrillation in 83%. Among these, the mean CHADS2 score was 1.8.

For the primary outcome, the event rate in the self-testing group was 7.9% per patient-year vs. 8.9% per patient-year in the conventional testing group (p = 0.1). For the individual outcomes, death occurred in 3.4% vs. 3.7%, stroke occurred in 0.7% vs. 0.8%, and major bleeding occurred in 3.9% vs. 4.5%, respectively, for self-testing vs. conventional-testing.

The time in target range was 67% vs. 62% (p < 0.05), and patient satisfaction was 48 vs. 49 points on the Duke anticoagulation satisfaction score (p < 0.05), respectively, for self-testing vs. conventional-testing.


Patient self-testing for INR monitoring does not reduce the composite outcome of death, stroke, or major bleeding. Despite this, there was no signal for increased adverse events, such as major bleeding, with self-testing. For select patients, self-testing may be a viable alternative to conventional testing.


Presented by Dr. Alan Jacobson at the American Heart Association Annual Scientific Sessions, New Orleans, November 2008.

Clinical Topics: Anticoagulation Management, Valvular Heart Disease

Keywords: International Normalized Ratio, Stroke, Warfarin, Heart Valve Diseases, Personal Satisfaction, Patient Satisfaction, Hemorrhage

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