Quality Assurance in Hemostasis: The Perspective from the College of American Pathologists Proficiency Testing Program

Abstract

External quality assurance (EQA) is an important component of the total quality assurance program of a clinical hemostasis laboratory. The College of American Pathologists (CAP) helps meet this requirement by providing a proficiency testing program that evaluates a broad range of hemostasis methods and analytes. This article reviews the published experience of the CAP proficiency testing program in hemostasis. The purpose is to formulate general conclusions about the benefits of EQA. Between 1963 and 2006, the performance characteristics of a variety of tests have been evaluated, including the prothrombin time, activated partial thromboplastin time, coagulation factor activity assays (e.g., fibrinogen, factor [F] VIII, FIX, FXI), von Willebrand factor assays, unfractionated heparin monitoring, lupus anticoagulant testing, and platelet function. Based on the results of these evaluations, the major benefits of EQA are to (1) enhance patient care and safety through improved laboratory testing; (2) characterize test accuracy and precision across multiple methods; (3) correlate specific method variables with accuracy and precision; (4) identify interfering substances and quantify their effects across multiple methods; (5) identify clinical laboratories that are at risk for poor performance so that their performance can improve; and (6) satisfy accreditation and regulatory requirements.

External Quality Assurance of Fibrinogen Assays Using Normal Plasma: Results of the 2008 College of American Pathologists Proficiency Testing Program in Coagulation

“…This was consistent with College of American Pathologists data published 20 years ago showing method-specific biases as high as 77 mg/dL on normal plasma and method-specific CVs ranging from 7.4% to 21.6%. 16,17 Bias was still high for some methods in the current study, up to 27%, which was equivalent to about 80 mg/dL. Other external quality assurance organizations also observe high interlaboratory bias, and some groups suggest that this can be reduced by using a common fibrinogen calibrator, although this is controversial.…”

Assessment of clopidogrel non-response by the PFA-100® system using the new test cartridge INNOVANCE® PFA P2Y

“…In this survey, the precision of the closure time in normal subjects using the CEPI-and CADPcartridges was also shown to be relatively low (CV 21.1% and 18.6%, respectively) [33]. Despite this, for normal subjects not on antithrombotic therapy, the results are interpreted correctly as normal in 92.4% and 94.0% of cases.…”

Aspirin Responsiveness in Healthy Volunteers Measured with Multiple Assay Platforms

“…A study conducted by the College of American Pathologists on proficiency testing results across approximately 600 laboratory sites indicated that levels of precision with either normal or tirofiban-treated samples were low to very low, with CVs of 21.1% and 49.7% for normal and tirofiban-treated samples, respectively (15 ). Imprecision across sites for samples with abnormal platelet function could relate to technical factors such as time between blood draw and sample analysis (almost all studies claim analysis within 2 h of draw) and/or number and expertise of persons doing the testing (in our study, 2 dedicated laboratory technologists did all testing).…”