Dosing practices of physicians for anticoagulation with warfarin during inpatient rehabilitation.

OBJECTIVE To determine the percentage of international normalized ratios (INRs) maintained within the therapeutic range for patients receiving chronic anticoagulation treatment with warfarin during inpatient rehabilitation. DESIGN A consecutive, 4-month, retrospective chart review of all patients receiving oral anticoagulation treatment was conducted in a large academic rehabilitation center. The percentage of INRs within and out of the therapeutic range, frequency of blood samples, length of therapy, and warfarin dose prescribed by physicians were calculated. A total of 181 patients receiving chronic anticoagulation treatment were identified. A total of 3,709 blood samples were analyzed. In 74 patients, the primary physician recommended a therapeutic range (Group 1). In the remaining 107 patients, no therapeutic range was specified, and a target INR range of 2.0-3.0 was assumed (Group 2). RESULTS In Group 1, the INRs were in the recommended range in 38.2% of all blood samples. In Group 2, 37.6% of all blood drawn was within an INR range of 2.0-3.0. Statistical analysis showed that no better accuracy was obtained when the INR range was predefined by a physician (Group 1) or assumed to be in the 2.0-3.0 range (Group 2; P = 0.839). CONCLUSIONS Despite frequent physician monitoring, this study demonstrates the difficulty in maintaining INRs within therapeutic ranges for patients receiving oral anticoagulation. An overall tendency for underdosing is observed. Improvement is necessary, given the high morbidity and mortality associated with insufficient anticoagulation in rehabilitation inpatients.

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