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Noubouossie D.,Laboratory of Hematology and Haemostasis
Acta clinica Belgica | Year: 2012

Detection of anticardiolipin antibodies (ACA) is an independent laboratory criterion for diagnosis of antiphospholipid syndrome (APS). Alternative methods to ELISA were recently developed such as automated chemiluminescence immunoassay (CLIA). We compared a CLIA to an ELISA kit for the detection of IgG isotype of ACA. 87 routine samples from 75 patients suspected of having APS were tested using each method. Cut-off values were calculated in our laboratory for each test using 99th percentile of 50 normal controls. Cut-off values were >20 GPL for ELISA and > 2 GPL for CLIA. Overall agreement (OA), agreement for positive (AP) and agreement for negative (AN) cases were 56.3%, 49.2% and 77.2% respectively. Most discrepant results were positive with ELISA and negative with CLIA. However, OA, AP and AN increased to 82.1%, 84.6% and 80% respectively when CLIA was compared to the repeated ELISA performed at least 12 weeks later. When correlated with APS-related clinical background, CLIA showed lower sensitivity, higher specificity and higher likelihood ratio (LR) as compared to first ELISA whereas these parameters were similar to those of the repeated ELISA. No association was found between any test results and APS-related clinical background of the patients. Using our own cut-off value (> 2GPL), sensitivity, specificity and LR of CLIA to identify patients with APS were respectively 100%, 72.3% and 3.6. A ROC curve showed that at 7.5 GPL cut-off value, specificity and LR improved to 91.1% and 11.25 respectively, without affecting sensitivity. A strong correlation was observed between CLIA results and APS (Chi2 = 12.25; p < 0.001). The performance of CLIA is as good as a repeated ELISA test to detect IgG ACA in suspected APS patients. It is fully automated, which represents several advantages over semi-manual ELISA techniques for its implementation in a routine laboratory.

Nguyen V.T.P.,Laboratory of Hematology and Haemostasis | Vancles P.,Provincial High School of Hainaut-Condorcet | Rozen L.,Laboratory of Hematology and Haemostasis | Noubouossie D.,Laboratory of Hematology and Haemostasis | Demulder A.,Laboratory of Hematology and Haemostasis
Immuno-Analyse et Biologie Specialisee | Year: 2013

The aim of this study is to evaluate the analytical performance of the new Sysmex XN-2000® analyzer in our routine laboratory. Overall, 798 adult and 340 pediatric blood samples were analyzed during a period of 3weeks on the Sysmex XN-2000® and Advia 2120i® as well as 100 body fluids. Analytical parameters as within-run and inter-day precisions, carry-over, linearity, limit of quantification, stability are excellent for the complete blood count (CBC) and correlation with Advia results shows high concordance between most parameters, except for the monocytes counts which are systematically higher with the Sysmex XN-2000®. The body fluids module shows high precision (CV<10%) for WBC with negligible carry-over and excellent linearity. However, the BF module cannot give a number of RBC below 1000μL. RBC results are only provided in interval of 103/μL cells with no intermediate counts. We concluded that the Sysmex XN-2000 provides highly reliable results. However, in our view, improvement of RBC count is mandatory and impairs full-automated counts of this kind of samples. © 2013 .

Rozen L.,Laboratory of Hematology and Haemostasis | Copette F.,Laboratory of Hematology and Haemostasis | Noubouossie D.F.,Laboratory of Hematology and Haemostasis | Demulder A.,Laboratory of Hematology and Haemostasis
Clinical Laboratory | Year: 2013

Background: Our current activated partial thromboplastin time (APTT) reagent (PTT-A) is often prolonged for unexplained reasons. Methods: We decided to compare this reagent with an alternative reagent (Cephascreen) and with our second line APTT (Actin FS) in terms of cut-off values, sensitivity to in-vitro coagulation factor deficiencies, sensitivity to lupus anticoagulant (LA), and in vivo sensitivity to unfractionated heparin (UFH). Results: Actin FS, PTT-A, and Cephascreen were prolonged for FVIII level at 60%, 40%, and 40% respectively, FIX at 50%, 25%, and 35%, and FXI at 60%, 20%, and 50%. PTT-A showed the same sensitivity and specificity as Cephascreen to LA. Actin FS and PTT-A appeared less suitable to monitor UFH regarding the CLSI criteria. Conclusions: Cephascreen fulfilled the CLSI performance criteria, with a good compromise in terms of sensitivity to factor deficiency and with a substantial reduction of complementary analysis in our routine practice.

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