Randomized Controlled Trial of Patient Self-Testing of Warfarin Therapy Using an Internet Based Expert System

Indications for anticoagulant treatment to prevent thromboembolic disease have increased in recent years. INR must be monitored frequently to determine the safest dose and to minimize the risk for thrombotic and haemorrhagic complications. Standard warfarin therapy is associated with rates of major haemorrhage of up to 5-9% annually and recurrent venous thromboembolism of up to 8%. These event rates are dependent of the model of care used to manage warfarin therapy, with better outcomes associated with home testing of the INR which enables patients to monitor their response to warfarin more frequently. INR results must still be 'managed' by communicating the data to the healthcare provider, usually be telephone or fax.

In this study we will evaluate a novel method of PST; supervised PST with an internet based expert system, which 'manages' patients on oral anticoagulation by utilizing clinical and laboratory data provided by the patient and dose adjustment and retesting algorithms derived from clinical practice. Patients will be randomized to either 6 months of supervised PST or routine medical care by the AMS. At the end of the 6 month period, each patient will then 'cross over' to the other management regimen and the difference in TTR between the two periods will be compared.