Computerized management of oral anticoagulant therapy: experience in major joint arthroplasty.

Objective: Evaluation of the safety and potential cost savings of a computerized, laboratory-based program to manage inpatient warfarin thromboprophylaxis after major joint arthroplasty.

Design: A consecutive-case study of adults.

Setting: A tertiary care orthopedic institution.

Patients: Patients requiring joint arthroplasty who had no recent episodes of thromboembolic disease, no mechanical heart valve, atrial fibrillation, severe liver disease or baseline international normalized ratio [INR] greater than 1.3 admitted over a 54-month period (July 1994-December 1998). All patients received a standard regimen of warfarin beginning on the evening after the operation. Four hundred and thirty randomly selected patients managed by the program were followed up by telephone survey 3 months after discharge. Patients exhibiting erratic responses to warfarin were withdrawn from the program and managed individually thereafter.

Intervention: Major joint arthroplasty with warfarin therapy administered through the computerized program.

Main Outcome Measures: Test results maintained within the desired therapeutic range (INR 2.0-3.0), clinically severe bleeding episodes, readmission rates, clinically symptomatic and venographically proven episodes of venous thrombosis or pulmonary embolism.

Results: Over the study period 5629 patients underwent joint arthroplasty; 5,372 patients were considered for the program; 332 patients were ineligible and were managed individually; 311 entered patients did not complete the program. This left 4,729 patients who completed the program. In 2932 (62%) patients test results were maintained in the desired therapeutic range. The major bleeding rate was less than 0.5%, the readmission rate was 3.8%, the deep venous thrombosis rate was 3.7% and the pulmonary embolism rate was 0.2% with no thromboembolic related deaths in the small sample cohort.

Conclusions: The majority of patients requiring warfarin thromboprophylaxis can be safely and effectively managed by this laboratory-based computerized program while in hospital. Significant potential cost savings in nursing time could be achieved.