New study shows warfarin weekly self-testers achieve better control with management by exception protocol

Gary Liska

In a study recently published in Nursing 2014, atrial fibrillation patients on warfarin therapy who self-tested their coagulation (via international normalized ratio [INR]) and were remanaged by their clinicians using a “Management by Exception” protocol had better warfarin control than traditional self-testers.¹ The protocol, in which patients followed specific clinic-issued, written instructions for managing out-of-range INR self-test results within a predetermined safety range, also benefited clinics by reducing the need for telephone follow-up and related costs.

The Management by Exception study complements the findings of the Self-Testing Analysis Based on Long-Term Experience (STABLE) study, first presented at the American College of Cardiology meeting in 2012.² These findings are to be published on March 24, 2014, in the American Journal of Managed Care. While the STABLE study confirmed that weekly testing was the optimal testing frequency for patients taking warfarin despite their previous stability, the Management by Exception study provides an actionable patient protocol that clinics can implement to make weekly testing viable over the long term.

Background

Warfarin has been the standard of anticoagulation care for preventing thromboembolic events for more than 50 years. Regular INR testing is needed to maintain drug levels within the therapeutic range, as dangerously high or low test results can increase patient risk of major bleeding 7-fold and stroke 4-fold. 

INR testing is increasingly being performed by patients in their homes. Although home testing has been embraced by many physicians and coagulation clinics, remanagement is often conducted by live telephone dialogue for each out-of-range patient result, regardless of whether the result is slightly or significantly out of range. This frequent remanagement requires substantial staff time and, in some cases, may limit a practice’s testing frequency based on workload rather than clinical decision making. Alere, the global leader in near-patient diagnostics, supported this study to determine whether a Management by Exception protocol could automate the remanagement of INR self-testers without compromising patient safety or practice exposure.

Study and results

Four study centers enrolled a total of 72 patients with target INR of 2.0 to 3.0 in the 6-month protocol, during which they self-tested weekly and reported their results via telephone. They were contacted by their clinic only if their INR results were less than 1.8 or greater than 4.0. INR results were compared with those from each patient’s previous 6 months, during which traditional self-testing testing and follow-up was conducted. 

The study achieved its primary end point of demonstrating that the investigational protocol was noninferior to traditional self-testing care. Self-testers achieved a similar proportion of time within therapeutic INR range during the 6-month protocol use compared to the 6 months prior to the protocol use (65.6% vs 66%, respectively). A significant 32.5% decrease, however, was observed in the number of critical value test results (<1.5 or >5.0) compared to the preprotocol phase, thus dramatically reducing the risk of bleeding and thrombotic events.

The protocol also eliminated the need for 350 telephone outbound calls to patients, which led to improved satisfaction scores among both patients and clinics, and could potentially free up staff to spend more time caring for patients at higher risk. The reduction in phone calls also realized a total cost savings of $2062.50 among the 4 participating clinics during the short 6-month window of the study.

These results demonstrate that a Management by Exception protocol can effectively automate patient care, without increasing patient or practice risk, while empowering patients to be a partner in their care. Most importantly, self-testing with Management by Exception enhanced the safety of warfarin therapy.

References

1. Burgwinkle P, Pigott V, Liska G, Koshy T. Follow the protocol: teaching patients to self-test. Nursing 2014. 2014;44(3):20–22.

2. Ansell J. 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. Chicago, IL: March 2012.

Mr Liska is global director, clinical development & education, Scientific Affairs, Alere, and coauthor of the Management by Exception study.