Patient Self-Testing of Prothrombin Time After Hip Arthroplasty

C. Anderson Engh, Jr., MD, William J. Culpepper II, MA, Patricia A. Charette, RN and Rachel Brown, from the Anderson Orthopaedic Research Institute, Alexandria, Va.

J South Orthop Assoc. 2001;10(3) 

In This Article

Discussion

This study confirmed that the majority of Medicare patients can obtain a reliable prothrombin time when using the self-testing device in their homes. This conclusion was evidenced by the high reliability correlation obtained by comparing the self-test results with the laboratory venipuncture results and with the home health nurse's results from the self-test device. Additionally, patient self-testing allowed closer monitoring (twice a week versus once a week), resulting in a higher percentage of patients staying within the target therapeutic range.

While this is encouraging, several areas of concern need to be addressed. Despite two training sessions before discharge, this group of patients had some difficulty obtaining a valid result in the first weeks. During the latter half of the study period, they were able to obtain valid results with fewer finger sticks. Likely, extra training would have minimized this learning curve. However, the number of attempts required to obtain a valid result did not affect the reliability of the test results.

Another concern is that 7 of 46 patients (15%) did not pass the initial training. This may have been related to the design of the device, which has a rather narrow recess in which the target cartridge resides (Figure). This design made it difficult for some of our elderly patients to see the target for their blood and to hold their finger still enough to apply a drop of blood to the target. This difficulty resulted in an inadequate blood sample, and the test had to be repeated, requiring another finger stick.

The potential outpatient Medicare savings with patient self-testing using the CoaguChek device is marked. When the estimated costs of monitoring with the CoaguChek device are compared with the cost of our standard protocol, the savings per patient is approximately $260. If one were to do two laboratory prothrombin time tests per week to achieve a similar improvement in the quality of care, the cost difference would be approximately $896 per patient.

These findings suggest that, using the self-testing device in this study, patient self-testing of prothrombin time is a reliable and cost-effective method for monitoring the anticoagulation status in a select group of elderly patients receiving anticoagulant therapy for a short period after THA. We limited the study to Medicare beneficiaries and those in our own geographic area to improve compliance with the study protocol. Allowing use of the device by all patients prophalactically treated with Coumadin after THA may decrease the percentage of untrainable patients. Additionally, improvements in the design of the device and refinements in the patient training process should decrease the number of finger sticks needed to obtain results, as well as the number of patients who are unable to use the device.

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