Quality Improvement Initiative for Pharmacist-Assisted Warfarin Dosing: Implementation and Evaluation of a New Protocol

Background and Objective: A Pharmacist-Assisted Warfarin Dosing (PAWD) program was implemented for patients in the cardiac program of the authors’ hospital in 1996. Within the PAWD program, certified pharmacists, under the direction of physicians, are responsible for warfarin dosing according to an approved protocol. The aim of the program was to have the international normalized ratio (INR) of at least 70% of patients within the therapeutic range at day 4 or 5 after initiation of therapy. However, a preliminary assessment showed that pharmacists were able to use the approved protocol for only 50% of the doses ordered, and only 61% of patients reached the therapeutic range by day 4. A quality improvement initiative was undertaken, and the warfarin protocol was modified. The current study reports the results of a retrospective comparison of outcomes before and after the quality improvement initiative. Methods: The authors compared outcomes for 59 patients enrolled in the PAWD program under the original protocol and 28 patients under the updated protocol. Results: Pharmacists were able to follow the updated protocol in a greater proportion of cases than had been the case with the original protocol. In addition, the mean INR was more often within the therapeutic range when the updated protocol was used, reaching statistical significance on days 5 and 6. Bleeding developed infrequently with either protocol, and vitamin K was used sparingly. Thrombosis did not occur in any patients. Conclusions: Through a continuous quality improvement process, the PAWD program was enhanced and the number of days on which INR was within the therapeutic range increased. These improvements should reduce the frequency of negative patient outcomes (e.g., adverse or thromboembolic events).