Naslov
Evaluation of in-house normal pool plasma for activated partial thromboplastin time mixing test as a part of diagnosting protocol for lupus anticoagulant detection.

Autori
Margetić Sandra, Butorac Tihana, Novosel Renata, Vrkić Nada

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, ostalo

Skup
XXIV Congress of the International Society on Thrombosis and Haemostasis

Mjesto i datum
Amsterdam, Nizozemska, 29.06.2013. - 04.07.2013

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
lupus anticoagulant; APTT mixing test; in-house pool normal plasma; commercial normal plasma

Sažetak
Background: Mixing test is commonly used as screening assay for laboratory investigation of inhibitors, thus respresenting an integral part of routine diagnostic protocol for lupus anticoagulant (LA) detection. The first criterion in identifying LA is prolongation of at least one laboratory test dependent of phospholipids, such as the activated partial thromboplastin time (APTT). This prolonged test must then be repeated on a mixture of patients plasma and normal plasma (APTT mixing test, APTTmt) to distinguish between inhibitor such as LA and a single factor deficiency. Aims: The aim of this study was to evaluate in- house pool normal plasma (NP) for APTTmt compared with commercial NP that is routinely used in our laboratory in the diagnosting protocol for LA detection. Methods: A total of 158 subjects were evaluated for LA, of which 11 subjects were LA positive. In-house pooled NP was obtained from 40 subjects directed to routine screening for prothrombin time (PT) and APTT, without any known coagulation disorder and with PT and APTT results within reference interval. Immediately after collection and centrifugation (3000 rpm 10 minutes), in-house pooled NP was divided into aliquots and frozen at -20C until analysis. Immediately before use, aliquoted in- house NP was thawed at 37C for 15 minutes. Commercial NP (Control plasma N, Siemens, Germany) was routinely used for APTTmt (Actin FSL, Siemens, Germany). Patients samples were mixed in the equal volume (1+1) with commercial NP as well as with in-house pool NP and evaluated in parallel for APTTmt. For in-house prepared pool NP we determined within-run precision by ten consecutive measurements of APTTmt and between-run precision by measuring of APTT in 10 consecutive days after freezing and thawing of aliquoted in-house NP. Comparison of APTTmt results with commercial NP and in-house NP was evaluated by Passing-Bablok regression and Bland and Altman difference plot. Results: Within-run coefficient of variation (CV) was 1.5% for APTTmt determined with in- house pool NP. Between run CV was 2.4% for APTT determined in aliquoted pooled NP. The results of APTTmt (seconds) comparison expressed as median (range) were as follows: in-house NP 27.0 (22.0-32.0) ; commercial NP 27.0 (23.0- 33.0). Passing and Bablok regression analysis showed that there were no significant constant or proportional differences between the two methods: regression line equation y=0.000+1.000x ; 95% confidence interval (CI) for intercept 0.000 to 5.200 and 95%CI for slope 0.800 to 1.000, thus indicating good agreement, linear relationship and statistically unbiased results between in-house and commercial NP used for APTTmt. These results were also confirmed by Bland and Altman difference plot. Commercial NP and in-house NP gave the same number of positive screening LA results (11/11) and positives were detected in the same specimens. Conclusions: Comparison between in-house pool NP and commercial NP for APTTmt indicated that a careful selection of donors allows use of in- house pooled NP that fits the quality demands for routine APTTmt. Our results confirmed that use of in-house prepared NP could be implemented in routine diagnostic protocol for LA detection.

Izvorni jezik
Engleski

Znanstvena područja
Kliničke medicinske znanosti

Napomena
Broj sažetka: PB-1.51-4 Postersko izlaganje i usmena prezentacija rada

POVEZANOST RADA