Anticoagulation monitoring part 1: warfarin and parenteral direct thrombin inhibitors.
OBJECTIVE
To review the availability, mechanisms, limitations, and clinical application of point-of-care (POC) devices used in the management of warfarin and parenteral direct thrombin inhibitors.


METHODS
Scientific articles were identified through a MEDLINE search (1966-August 2004), manufacturer Web sites, additional references listed in articles and Web sites, and abstracts from scientific meetings.


METHODS
English-language literature from clinical trials was reviewed to evaluate the accuracy, reliability, and clinical application of POC monitoring devices.


RESULTS
The prothrombin time expressed as the international normalized ratio (PT-INR) is a well-established test for monitoring warfarin anticoagulation. Multiple devices are available for POC testing. Because there is no universally accepted standard, the performance of each device is typically tested against a standard test performed in a reference laboratory. Performance of currently available devices, as measured by correlations to a standard reference laboratory PT-INR, may be considered very good and acceptable for use in patient care. Utilization of patient self-testing and patient self-monitoring of warfarin anticoagulation using POC devices is increasing. Parenteral direct thrombin inhibitors are typically monitored using a standard laboratory activated partial thromboplastin time. Some research has shown that POC monitoring of direct thrombin inhibitors using the ecarin clotting time is helpful for patients undergoing cardiopulmonary bypass surgery, although that test is not readily available.


CONCLUSIONS
POC testing for anticoagulation therapy has been available for >20 years. Multiple POC devices are available to monitor warfarin. There is some variability in results between devices and between reagents used in the same device. Despite these limitations, POC monitoring of warfarin via the PT-INR is an integral part of clinical practice. Additional research evaluating POC monitoring of direct thrombin inhibitors is necessary.
Spinler
Sarah A
SA
Cardiovascular Division, Department of Medicine, Philadelphia College of Pharmacy, University of Pennsylvania, Philadelphia, PA 19104-4495, USA. s.spinle@usip.edu
Nutescu
Edith A
EA
Smythe
Maureen A
MA
Wittkowsky
Ann K
AK
D000925:Anticoagulants / Q000008:administration & dosage / Q000627:therapeutic use*; D000991:Antithrombins / Q000008:administration & dosage / Q000627:therapeutic use; D006801:Humans; D019934:International Normalized Ratio / Q000379:methods; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000592:standards; D019095:Point-of-Care Systems / Q000592:standards; D011517:Prothrombin Time / Q000379:methods*; D015203:Reproducibility of Results; D014859:Warfarin / Q000008:administration & dosage / Q000627:therapeutic use
D000925:Anticoagulants; D000991:Antithrombins; D014859:Warfarin