More frequent INR testing supported by evidence

More frequent home testing has become a safer approach to managing warfarin. In the last ten years there have been dozens of clinical trials and papers written on improving the safety of warfarin for the 2-4 million patients on warfarin.

Physician’s decisions are driven by clinical evidence and recommendations by today’s experts in the field of warfarin. Medicare made a landmark decision in 2002 to completely cover the cost of a patient’s home International Normalized Ratio (INR) monitor and 80% of the testing strip costs. The data supporting more frequent home testing was unmatched by any study that showed monthly testing was superior to more frequent testing.1

Regardless of your physician type, there is a study that demonstrated improved time in range for patients. Studies included short term, long term and all reasons for patients being on warfarin. The investigators that reviewed the studies (below) noted there were no studies showed traditional testing was superior to more frequent testing.

Author, Year1 Indications # of Patients Type of Study Results
MHV AF Other Time in Range
White, 1989

X

 

X

50 RCT 17% increase
Ansell, 1995

X

 

X

40 Cohort 20% increase
Horskotte, 1996

X

 

 

150 RCT 34% increase
Hasenkam, 1997

X

 

 

41 Case Ctr. 24% increase
Byeth, 1997

X

X

X

325 RCT 24% increase
Sawicki, 1999

X

X

 

179 RCT 23% increase
GELIA

X

 

 

278 RCT 11% increase
ESCAT

X

 

 

1,200 RCT 18% increase
Chromheecke

X

X

X

50 RCT 6% increase
Watzke, 2000

X

X

X

102 RCT 11% increase

Many doctors fear home testing may increase their risk in managing patients. Fears include patients’ will self-medicate or not return to the office. Patients need to realize that improved safety on warfarin includes routine office visits. Home testing is not a replacement for doctor’s care.

Physicians will need reassurance from patients that will be responsible. There are many variables that go into the INR test result, well beyond what patients can manage on their own.

  1. Decision Memo for Prothrombin Time (INR) Monitor for Home Anticoagulation Management (CAG-00087N). 2001.