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 chroni c 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, therap eutic range, frequency of blood samples, length of therapy, and warfarin do se prescribed by physicians were calculated. A total of 181 patients receiv ing chronic anticoagulation treatment were identified. A total of 3709 bloo d samples were analyzed. In 74 patients, the primary physician recommended a therapeutic range (Group 1). In the remaining 107 patients, no therapeuti c 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 rang e of 2.0-3.0. Statistical analysis showed that no better accuracy was obtai ned when the INR range was predefined by a physician (Group 1) or assumed t o 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 obse rved. Improvement is necessary, given the high morbidity and mortality asso ciated with insufficient anticoagulation in rehabilitation inpatients.