Home and Community Care Digest

Home and Community Care Digest June 2004 : 0-0

Using a Portable Coagulometer To Monitor Homebound Elderly Patients Taking Warfarin Can Save Costs


A cost-savings analysis demonstrates how the use of portable coagulometers in the home setting affects costs. An international normalized ratio (INR) (a ratio that measures blood clotting) was measured for each patient using two methods: 1) a traditional, laboratory-based prothrombin time and 2) a point-ofcare coagulometer. The costs for materials, procedures, transportation, and labor were summed for both methods. It was found that the cost of INR determination by the portable coagulometer was significantly less than the traditional method ($6.85 vs. $17.30).
Background: Warfarin is an effective and frequently used anticoagulant. Careful monitoring of warfarin is especially important in older patients who have a risk of thrombotic and bleeding complications. This monitoring must be administered to ensure proper therapeutic levels of anticoagulation. Portable instruments that measure the prothrombin time and calculate the international normalized ratio (INR, a ratio that measures blood clotting) from a drop of whole blood have the potential to simplify warfarin monitoring, especially for homebound patients. The accuracy and precision of these coagulometers are acceptable and have been approved for use in the U.S.A. since 1995. This study examines whether the use of portable coagulometers in the home health setting saves costs compared to the traditional method.

Methods: Data were collected through a home health agency in St-Louis, USA. Eight registered cardiac nurses, each of whom visited approximately five patients at home per day, participated in the study. In the existing program, nurses obtained blood samples during home visits and placed these in drop boxes for pick up and analysis at a central laboratory. Thirty-five elderly patients (mean age 67 years) receiving cardiac home health care and long-term oral anticoagulation were evaluated with paired measurement of the INR by both the traditional, central laboratory-based test, and a point-of-care coagulometer. To ensure that results from both methods were clinically comparable, 180 randomly selected paired INR results were examined for correlation and agreement. Costs of materials, procedures, transportation, and labour were summed to determine total cost for both methods.

Finding: The average cost of INR obtained by a coagulometer was $6.85. This included the cost of test strips ($3.50), depreciation of the coagulometer ($1.33), training ($0.05), quality control ($0.37), six repeat tests due to technical error ($0.87), and three confirmation tests for INR values above 4 ($0.73). From the societal perspective, the cost of obtaining an INR via the traditional method included reimbursement for miles driven, the wage for the nurse's time used during the transport, and laboratory cost. This averaged $17.30 per INR. From the home health agency perspective, the cost averaged $10.67 per INR, because the agency did not have to pay for processing an INR. From the societal perspective, there was a cost saving of $10.45 (the difference of $17.30 - $6.85) per INR. From the perspective of the home health agency, there was a cost savings of $3.82 (the difference of $10.67 - $6.85) per INR.

Conclusions: From both the societal and home care agency perspective, the use of a point-of-care coagulometer for monitoring warfarin use in the home care setting resulted in reduced costs compared to the practice of using a central laboratory to provide test results.

Reference: Cheung, DS., Heizer, D., Wilson, J., & Gage, BF. "Cost-Savings Analysis of Using a Portable Coagulometer for Monitoring Homebound Elderly Patients Taking Warfarin", American Journal Geriatric Cardiology, 2003, 12 (5): 283-287.


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