Influence of Warfarin Regimen Type on Clinical and Monitoring Outcomes in Stable Patients in an Anticoagulation Management Service

Options for dosing warfarin include same daily dosing, such as 7 mg/day, and alternate-day dosing, such as 5 mg Monday and Thursday, and 7.5 mg all other days. Some practitioners favor same daily dosing because it is simple, whereas others prefer alternate-day dosing because it requires a single tablet size. Computerized records of patients followed by an anticoagulation management service were reviewed retrospectively to identify those whose anticoagulation was stable with one of these two dosing methods. Clinical and monitoring outcomes were compared between groups. Rates of hemorrhagic and thromboembolic complications were similar in the two groups, as were monitoring outcomes, including clinic visits/year, warfarin dosage adjustments/year, and percentage of international normalized ratios within range. Patients receiving the same daily dose reported lower rates of confusion (0% vs 7%) and dosing errors (3.3% vs 14%) that those receiving alternate-day dosing, and expressed a stronger preference for their regimen (40% vs 1.5%). When selecting a regimen, consideration must be given to patient-specific risk of confusion and dosing errors, associated costs, practicality and precision of dosing adjustments, and patient preference.