Abstract American Society of Hematology December, 2002

Blood 2002:100(11)

Implementation Of A Warfarin Dosing Method At A Community Health Center

David Shepro, MD, Commonwealth Hematology-Oncology, University of Massachusetts Medical School, Worcester, MA; Hudson Physician Communications, Inc, Holden, MA;Nancy Morden, MD, Theodore Shoemaker, MD, Family Health Center, University of Massachusetts Medical School, Worcester, MA

Background:

There is considerable variability in methods of warfarin dose adjustments by health care providers.  These inconsistencies can contribute to adverse outcomes and can limit the effective implementation of consensus guidelines.  We examined the implementation of the Anticoagulation-Advisor® slide-chart system of warfarin dose adjustments and dosing nomograms.  This system provides an easy-to-use, consistent, and coherent method to calculate warfarin doses.

The Family Health Center of Worcester, Inc. is a federally funded community health center that serves a traditionally underserved and culturally diverse population in Worcester MA .  Physicians, along with RNs, NPs, and physicians-in-training currently manage approximately 50 patients on warfarin anticoagulation (AC) therapy.  A quality-improvement program that utilized personal communications, didactic programs, centralization of AC records, new AC flow sheets, and the Anticoagulation-Advisor (AA) slide-chart system was implemented during the summer and fall, 2001.

Methods:

AC records from 1/1/02 – 7/31/02 were reviewed.  Cases with at least 8 weeks of chronic AC data were included.  The number of INRs obtained, number of INRs out of the planned therapeutic range, number of INRs in an expanded therapeutic range, whether or not the AA system was used to adjust warfarin dose, and reasons for deviation from the system were noted.  The expanded therapeutic INR range was defined as INR 1.5 – 3.5 for INR target 2-3 or  INR 2.0 -  4.0 with INR target 2.5 – 3.5.

Results:

27 records met the criteria for review.  There were a total of 417 INR measurements. The INR was in the therapeutic range in 197 (47 %) measurements in this challenging population of patients.   The INR was in the expanded therapeutic range in 305 (73 %) measurement.  There were 15.4 INR measurements per patient during the study period, corresponding to 2.2 INRs/patient/month.  No patient was reported to have bleeding or acute thrombosis during the study period.  The degree to which healthcare providers used the nomogram/ Anticoagulation-Advisor system in response to different INR groups is tabulated.

Reasons for practitioners not utilizing the AA system recommend doses were uncertainty of the dose that the patient was taking, uncertainty of patient compliance in prior several days before out-of-range INR, peri-procedure dose adjustments, and unknown. 

Conclusion:

A system for adjusting doses of warfarin was used 80 % of the time by a broad spectrum of physician and non-physician community-based health care providers.  This system can contribute to implementation of consensus antithrombotic guidelines and high quality anticoagulation dose management.