Expansion of Self- Management of Warfarin: A Quality Improvement Study

Students: Melissa Haggerty* and Lindsey Severud*
Mentors: Kerry A. Milner, Heather Ferrillo
Major: Nursing


In this quality improvement (QI) study self-management (SM) is defined as the self-testing of the international normalized ratio (INR) and self-dosing of warfarin. This practice results in tighter control of the INR and is as safe and effective as provider management.


The primary aim was to expand SM of warfarin in the Yale New Haven Health System (YNHHS). Secondary aims were to explore the barriers to SM of warfarin in eligible patients that choose to self-test their INR but prefer healthcare provider dosing of warfarin; and pilot the engagement of undergraduate nursing students in faculty research.

Sample and Setting:

The setting was a large cardiology practice in the YNHHS. Patients who were ³18 years of age, English speaking and reading, INR self-testing ³3 months, compliant with weekly or bi-weekly INR self-testing, and never used SM were invited to participate. For the usual care arm of this study, patients taking warfarin but not self-testing or SM, were randomly selected from the electronic health record and outcome data will be abstracted after May 2016.


For the SM study arm, participants attended a 2-hour education class where they learned how to adjust their warfarin dose based on INR value and the nurse practitioner reviewed the effects of diet, other medications, and any illness/injury or surgery. Participants continued INR self-testing weekly or biweekly and began self-adjusting their warfarin dose.

Participants continued to report their INR levels to the cardiology office to maintain safety. There was a 2-week learning period before data collection began where the researchers contacted patients to check warfarin dosing for accuracy.

Outcome Measures:

1. Percentage of time the INR remained in therapeutic range (TTR) for their diagnosis and co-morbidities.

2. Mean variance of the INR from the patient prescribed therapeutic range, frequency of testing (weekly or bi-weekly).

3. Variance categories (mean variance ≤0.4, no variance, mean variance >0.4).

4. If the variance was higher than or lower than their designated range.

5. Adverse events (minor or major bleeding or thromboembolic events). Minor bleeding was defined as any bleeding due to the INR being high but not requiring the patient to access emergency care or hospital. Major bleeding was any bleeding due to the INR being high and requiring emergency care or hospitalization and/or vitamin K, FFP or blood transfusion. Thromboembolic events were defined as any new incidence of clotting related to the INR being low.


Study completion date is May 15, 2016 (results pending).

Lessons Learned:

This experience helped us to gain a better understanding of the scientific method of inquiry and the specific steps to follow for a rigorous, high quality study. The first step was to complete the National Institutes of Health training titled, Protecting Human Subjects Participants. The purpose of this training was to teach us the importance of protecting human subjects when carrying out research. We learned about human subject review committees and that researchers must submit a study protocol to the Institutional Review Board at SHU and gain approval before they can begin their study. We were also taught the importance of maintaining confidentiality of all study subjects and the safe storage of the study data. This is similar to what is expected of us as nurses in the clinical setting.

We were directly involved in several research activities. We participated in the educational sessions on SM of warfarin. We helped with the random selection of the usual care arm. We performed data entry and data checking for accuracy in Excel. We also learned that it takes a team of people with different specialties to carry out biomedical research. This is similar to the clinical setting where an inter-professional team is needed for high quality, cost effective patient care.


The research in self-management of Coumadin served a dual purpose in supporting a viable option for patient care improvement while providing the opportunity for student involvement in original research.

*Honors Senior