A Pilot Study Comparing Two Methods for Warfarin Management in Hospitalized Patients

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Background: The potential for medication errors in a hospital setting has led to a change from daily order writing to scheduled dosing. It has also been hypothesized that scheduled dosing may decrease the pharmacists' workload in a community teaching hospital. Objective: To evaluate the impact that scheduled warfarin dosing would have on patient safety for a pharmacist-run anticoagulation service. Methods: Two methods for managing warfarin in a pharmacist-run anticoagulation service were compared. A retrospective chart review was conducted on a random sample of 80 inpatients who received warfarin either from January 2006 through December 2006 (control/ daily dosing group) or from January 2007 through March 2007 (scheduled dosing group). Patients not managed by pharmacists or with a target international normalized ratio (INR) range other than 2 to 3 were excluded. Results: A total of 35 patients met inclusion criteria; 20 patients were in the daily order (control) group and 15 were in the scheduled dosing group. A total of 7 doses were omitted in the daily dosing group, compared with none in the scheduled dosing group. Of the 7, 4 were omissions in administration and 3 were order omissions. In the control group, the dose was changed 47 times (36%) compared with 23 times (28%) in the scheduled dosing group. In the daily dosing group, 28 (22%) INRs were within the therapeutic range and 97 (78%) were in the nontherapeutic range. In the scheduled dosing group, 24 (25%) INRs were within the therapeutic range and 72 (75%) were in the nontherapeutic range. Conclusions: Scheduled dosing eliminated omission-type medication errors and was more efficient than daily dosing. The process change decreased pharmacist workload without having a negative impact on patient care.