Alere STABLE study showed improved warfarin safety

Publication Date: 
Thu, 06/14/2012

Pending publication by the international anticoagulation expert and principal investigator Jack Ansell, MD, the Self-Testing Analysis Based on Long-Term Experience (STABLE)1 study redefines warfarin safety and practice management.

What is the STABLE study?

The STABLE study, the largest study of warfarin patient self-testing ever conducted, found that weekly patient self-testing provided the greatest safety for patients on warfarin long-term.1

It reviewed over 29,500 real-world patients and 3.1 million INR test results within the Alere Home Monitoring, Inc. database to determine if control of the drug warfarin could meet or exceed well designed clinical trial outcomes.

What are the results of the STABLE study?

The results of the Alere study exceeded any long-term study previously published which evaluated warfarin control.

  • Weekly home testing showed a 47% reduction in risk of major bleeding event or stroke
  • Weekly home testers time in INR target range surpassed time in INR target range in previous controlled trials by 12% (THINRS, Bloomfield 22-study meta-analysis)
  • Weekly home testers reached a greater than 70% time in INR target range 20 months sooner than the variable frequency testers (every two weeks or monthly testers)
  • Patients older than 74 years showed greater time in INR target range than younger patients
What are the results of the STABLE study?
Am I testing enough?

The weekly test frequency kept patients in their INR target range most often, more often than monthly testing. Testing your INR at home enables you to test at this frequency. Medicare and many private insurance now provides coverage for testing your INR weekly.

Improving warfarin safety begins with talking to your doctor about your interest in testing your INR at home. Home INR monitoring will help improve your control of warfarin. More frequent testing, typically performed by patient self-testing, is a valuable tool for detecting rises and falls in INR values and help you work with your doctor to make any adjustments to diet or medication dosing.2

Interested in obtaining a portable INR monitor and testing your INR at home?


Additional Information for Healthcare Professionals

At Alere, we know your goal is improve the safety of your warfarin patients and now the landmark STABLE study demonstrated weekly home testing showed a 47% reduction in risk (outlier test results that more than triple patients’ risk of a major bleeding event or stroke) over the variable testing frequency group.

The study also showed reduced critical value (INR < 1.5, > 5.0) test results by 47% over non-weekly testing frequency patients. Critical value test results increase your patients’ risk of major bleeding or thrombosis by more than 3 times than those patients in their target range.2, 3

The STABLE study:

  • Evaluated over 29,500 real-world patients (3.1 million INR test results) within the Alere Home Monitoring, Inc. database
  • Surpassed previous benchmark controlled trials: THINRS and Bloomfield 22-study meta-analysis by 12%
  • Demonstrated weekly testing provided optimal warfarin control at 74% providing a 47% reduction in critical value over variable (non-weekly) testers, resulting in reducing patient and practice risk
  • Showed high warfarin control was sustained throughout the 2.5 year study
  • Older adults (80-84 years old) had a higher TTR (73.1%) than younger adults (46-64) TTR (72.4%) when testing weekly.
  • Patients 65-74 years had the highest TTR (75.4%, weekly) of all age groups
  • Slightly more males than females perform patient self-testing (56% male, 44% female), however men showed a significantly higher overall TTR of 72.1% compared with females (66.6%)
The STABLE study

Demonstrated a mean TTR of 69.7% (SD 18.7), exceeding TTR of published controlled trials such as THINRS (TTR=66.2% weekly PST) and the Bloomfield et al 22-study meta-analysis (TTR=66.1%).


For more information regarding the study, download the poster sessions below presented at ACC (American College of Cardiology) and THSNA (Thrombosis and Hemostasis Summit of North America) or please contact your sales representative.

STABLE, presented at ACC STABLE, presented at THSNA
STABLE, presented at ACC
STABLE, presented at THSNA
Webinar Review of STABLE study

Jack Ansell, MD is the principal investigator for the largest patient self-testing study (STABLE) ever conducted. Dr. Ansell will be presenting the findings of the study he presented at the 61st Annual American College of Cardiology meeting.

Dr. Ansell is the chairman of medicine at Lenox Hill Hospital in New York City. Dr. Ansell is recognized as an international expert on anticoagulation and a member of: the American College of Chest Physicians, American Society of Hematology, the International Society of Thrombosis and Hemostasis, and the Anticoagulation Forum.

  1. Ansell, J. March 2012. Patient Self-Testing: Real-World Experience Within a Comprehensive Support Service Represents a New Standard of Care, Attaining High Quality Anticoagulation Control.Poster presented at: American College of Cardiology.
  2. Center for Medicare and Medicaid Services. Decision Memo for Prothrombin Time (INR) Monitor for Home Anticoagulation Management  (CAG-00087R) [Memorandum]. Baltimore, MD. 2008.
  3. Hylek, E., et al. An Analysis of the Lowest Effective Intensity of Prophylactic Anticoagulation for Patients with Nonrheumatic Atrial Fibrillation. NEJM, Vol.335, No.8, p.540-6. 1996.