Trials and tribulations in lupus anticoagulant testing

Favaloro, Emmanuel J.

doi:10.1515/cclm-2012-0578

Cited by 18 publications

(27 citation statements)

References 14 publications

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“…This study attempts to harmonize postanalytical data manipulation and interpretation, providing a simple and repeatable method to define cutoff values, which differentiates between positive and negative populations. This should minimize borderline and dubious results, sometimes discouraged in literature [8], allowing the harmonization of results reporting [13]. Moreover, the global interpretation of the analysis could be improved if different levels of positivity for each single test (dRVVT or SCT) are used and evaluated together.…”

Section: Discussionmentioning

confidence: 99%

“…This approach provides a reliable method for setting the upper limits on healthy subjects for dRVVT and silica clotting time (SCT) integrated assays [12], thus identifying the negative population. It is important to define a method for determining the cutoff value aiming to reduce equivocal borderline results and improving interlaboratory comparability [13]. A further issue is the definition of different positivity levels (weak, moderate and strong), which usually vary considerably from laboratory to laboratory due to the lack of common criteria [13,14], difference in instrumentation and reagents used, and reagent variability.…”

Section: Introductionmentioning

confidence: 99%

“…Laboratories do not always correctly distinguish normal subjects from LAC-positive ones, mainly because of the difficulty in identifying weak positives samples [13,15,16]. In addition, positivity levels are highly variable and difficult to interpret [17]; however, it is yet unclear whether a strong LAC is a greater risk factor for thrombotic complications than a weak one [16].…”

Section: Introductionmentioning

confidence: 99%

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Lupus anticoagulant

Poz

Pradella

Azzarini

et al. 2016

Blood Coagulation &Amp; Fibrinolysis

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Laboratory assessment of Lupus anticoagulant (LAC) is very challenging because of inter and intralaboratory variability, which makes it difficult to standardize and harmonize results expression. Five hospital laboratories in North-eastern Italy shared their efforts and their experience in a cross-laboratory study, conducting the diagnostic process as homogeneously as possible and providing a better interpretation for LAC positivity. Hundred normal samples from healthy subjects (20 from each center) were processed to confirm negative upper limits and calculate positivity cutoffs of LAC integrated assays, that is dilute Russell's viper venom time (dRVVT) and silica clotting time (SCT). Moreover, 311 samples previously diagnosed by the laboratories as positive for LAC were analyzed to characterize different positivity levels for each assay. As far as the analysis of healthy subjects is concerned, negative upper limits are set at 1.17 and 1.19 for dRVVT and SCT screen ratio, respectively. Positivity cutoffs are set at 1.20 for dRVVT and 1.23 for SCT, expressed as Test Ratio calculated on screen and confirm integrated tests. Positive results for each integrated assay are subsequently divided into three subgroups: weak, moderate and strong; the results obtained are presented as a score proposal that can provide LAC interpretation. The combined use of both dRVVT and SCT assays and the definition of different positivity levels may lead to clearer, more objective LAC reporting. An interpretative table for LAC-proposed score provides LAC-positive results and it is now adopted by all centers involved in the study.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lupus anticoagulant

Poz

Pradella

Azzarini

et al. 2016

Blood Coagulation &Amp; Fibrinolysis

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“…The anticoagulants mentioned previously, given as thrombosis therapy and affecting PC/PS/AT assays, also affect the clot-based assays used to identify LA, and can differentially produce both false-positive and false-negative results [6]. Although solid phase assays aPL assays are generally unaffected by these anticoagulants, they are instead biased by much higher inter-laboratory variation than LA testing [12,13], thereby limiting their clinical utility. In summary, some laboratories will report an aPL negative sample as being aPL positive, some laboratories will report an aPL positive sample as being aPL negative, and the strength of an aPL positive sample will also be variably reported.…”

Section: Antiphospholipid Antibodiesmentioning

confidence: 99%

The futility of thrombophilia testing

Favaloro¹

2014

Clinical Chemistry and Laboratory Medicine

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There has been increasing recognition of various laboratory markers of thrombophilia that are associated with increased risk of thrombosis either through hereditary (especially Factor V Leiden, prothrombin G20210A mutation, and protein C, S and antithrombin deficiencies) and/ or acquired means (e.g., antiphospholipid antibodies) over past decades. This has led to an explosion of clinical requests for these markers, that has now become virtually uncontrolled, and seemingly inclusive of everyone who has had a thrombotic event. Although these haemostasisrelated defects should be assessed in selective cases, the overuse (or misuse) of testing causes serious adverse outcomes and leads to the conclusion that, in general, testing for thrombophilia is futile.

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“…This particular lupus anticoagulant positive sample was so strong that titration of the sample to 1/32 dilution in normal plasma was required to obtain the highest dRVVT screen/confirm ratio (see Fig. 1a [9,12,14,15]). …”

mentioning

confidence: 99%

Decreased mean platelet volume in Gilbert's syndrome

Varol¹

2013

Blood Coagulation &Amp; Fibrinolysis

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Trials and tribulations in lupus anticoagulant testing

Cited by 18 publications

References 14 publications

Lupus anticoagulant

Lupus anticoagulant

The futility of thrombophilia testing

Decreased mean platelet volume in Gilbert's syndrome

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