The Diagnostic Accuracy of Bedside and Laboratory Coagulation: Procedures Used To Monitor the Anticoagulation Status of Patients Treated With Heparin

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Abstract

We evaluated the diagnostic accuracy of three bedside coagulation procedures, the Hemochron activated whole-blood clotting time (ACT) (International Technidyne, Edison, NJ), the CoaguChek Plus (Boehringer Mannheim, Indianapolis, Ind) activated partial thromboplastin time (APTT) and the TAS (Cardiovascular Diagnostics, Raleigh, NO APTT, before removal of arterial sheaths, in patients who received heparin therapy during percutaneous coronary angioplasty. As part of the postprocedure care, nurses performed bedside coagulation tests, removed the sheaths when appropriate coagulation criteria were met, and collected samples for laboratory APTT determinations and heparin assays performed with an automated chromogenic anti-Xa assay. Patients with heparin concentrations of 0.3 U/mL or more were classified as anticoagulated and those with concentrations less than 0.3 U/mL, as not anticoagulated. Analysis of the receiver operator characteristic (ROC) curve was used to rank the performance of the methods. Areas under the ROC curves ± SE for the laboratory APTT, CoaguChek Plus APTT, Hemochron ACT, and TAS APTT were 0.978 ± 0.016, 0.872 ± 0.044, 0.797 ± 0.039, and 0.795 ± 0.048, respectively. At cutoff values for the tests that provide greatest safety for the patients (no false-negative results), the false-positive rates for the laboratory, CoaguChek Plus, Hemochron, and TAS methods were 15%, 27%, 62%, and 100%, respectively. The laboratory APTT demonstrated the highest diagnostic accuracy in this application; however, turnaround rime for the test (50% of the results were reported in excess of 77 minutes) was inadequate for clinical decision making. To meet this requirement, we developed a point-of-care program using the whole blood APTT performed on the CoaguChek Plus analyzer.

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