Proficiency testing results for heparin-induced thrombocytopenia in north america.

Between 2010 and 2012, North American Specialized Coagulation Laboratory Association (NASCOLA) distributed five proficiency testing challenges to evaluate laboratory testing for heparin-induced thrombocytopenia (HIT). Results (n = 355) were submitted from 43 unique laboratories for 10 samples (3 positive, 2 weak positive, and 5 negative). The vast majority of results were from commercial enzyme-linked immunosorbent assay (ELISA) methods, predominantly polyvalent assays.

Protein C assay performance: an analysis of North American specialized coagulation laboratory association proficiency testing results.

To determine the performance and frequency of protein C reagents currently used by clinical laboratories, we analyzed North American Specialized Coagulation Laboratory Association (NASCOLA) protein C proficiency testing data from 6 surveys conducted in 2009 and 2010 (2009-1 to 2009-3 and 2010-1 to 2010-3). Interlaboratory coefficients of variation (CV) for commonly used reagents on a survey with normal protein C ranged from 8% to 12% for antigenic assays, from 4% to 7% for chromogenic activity assays, and from 7% to 22% for clot-based activity assays. CVs for commonly used reagents on specimens with abnormal protein C ranged from 15% to 24% for antigenic, 4% to 11% for chromogenic, and 10% to 17% for clot-based assays (averaged across 3 surveys).

Lupus anticoagulant testing: performance and practices by north american clinical laboratories.

Lupus anticoagulant (LAC) testing is important for evaluating patients with antiphospholipid syndromes and hypercoagulable states. We reviewed results of proficiency testing challenges (n = 5) distributed by the North American Specialized Coagulation Laboratory Association to examine LAC testing performed by participating laboratories. The activated partial thromboplastin time (APTT) and dilute Russell viper venom time (dRVVT) constituted major testing methods.

Analysis of von Willebrand factor structure by multimer analysis.

Analysis of von Willebrand factor (VWF) structure is achieved by performing a highly specialized procedure, VWF multimer analysis. The test is reserved for the reference or specialized laboratory environment. The assay is qualitative (though under some circumstances multimers may be quantified) in that it assesses the overall size distribution of VWF multimers as well as their individual internal structure.

Laboratory assessment of factor VIII inhibitor titer: the North American Specialized Coagulation Laboratory Association experience.

Quantification of inhibitory antibodies against infused factor VIII (FVIII) has an important role in the management of patients with hemophilia A. This article summarizes results from the largest North American FVIII inhibitor proficiency testing challenge conducted to date. Test samples, 4 negative and 4 positive (1-3 Bethesda units [BU]/mL), were distributed by the ECAT Foundation in conjunction with the North American Specialized Coagulation Laboratory Association and analyzed by 38 to 42 laboratories in 2006 and 2007.

Are laboratories following published recommendations for lupus anticoagulant testing? An international evaluation of practices.

Laboratory tests for lupus anticoagulants (LA) are commonly performed to evaluate thrombosis or suspected phospholipid antibody syndromes. To determine current LA testing practices, and if they conform to published recommendations, two questionnaires were distributed to clinical laboratory members of the North American Specialized Coagulation Laboratory Association (NASCOLA) and the ECAT Foundation (ECAT). The first and second questionnaires were completed by 113 and 96 laboratories, respectively.

Laboratory testing for lupus anticoagulants: pre-examination variables, mixing studies, and diagnostic criteria.

The latest international guidelines for the laboratory diagnosis of lupus anticoagulants (LA) date back to 1995 and are in need of revision. Various patterns of practice and interpretation by clinical laboratories have altered the intent or usage of the criteria and recommendations made at that time. Moreover, various topics in the preexamination phase of LA testing (such as the role of the clinician in test ordering, the impact of direct thrombin inhibitors or oral anticoagulant therapy, and patient biologic variation) need to be considered in future guidelines.

Protein S assays: an analysis of North American Specialized Coagulation Laboratory Association proficiency testing.

To assess current laboratory practice and the performance of different reagent-instrument combinations for protein S testing, protein S results from the North American Specialized Coagulation Laboratory Association (NASCOLA) proficiency testing surveys for 2002 and the first half of 2003 were analyzed. A written survey of NASCOLA laboratories also was performed to further assess current laboratory practices for protein S testing. The free protein S antigen assays and the Diagnostica Stago Staclot protein S assay were extremely accurate in detecting a heterozygous type I protein S deficiency.

Variability in clinical laboratory practice in testing for disorders of platelet function: results of two surveys of the North American Specialized Coagulation Laboratory Association.

Disorders of platelet function are important causes of abnormal bleeding that require laboratory tests for diagnosis. Currently there are limited guidelines on how to perform clinical testing for these disorders. The goal of our study was to obtain information on how disorders of platelet function are currently evaluated in clinical laboratories.