PIFA PLUSS P4 Assay for Screening of Heparin-Induced Thrombocytopenia

Compton, Frances; Alrabeh, Reem; Nguyen, Lisa Q; Nedelcu, Elena; Wahed, Amer; Nguyen, Nghia D.

doi:10.1093/labmed/lmy048

Cited by 4 publications

(8 citation statements)

References 13 publications

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“…Subsequently, nonagglutinated—but not agglutinated particles—will migrate through the membrane filter, so a negative test is shown by a blue color in the result well, and no color indicates a positive test. Despite the PIFA being approved in the United States, I am unaware of any peer‐reviewed data supporting its utility for HIT diagnosis; rather, available reports indicate lack of diagnostic value of this assay …”

Section: Pf4‐dependent Immunoassaysmentioning

confidence: 99%

Laboratory diagnosis of heparin‐induced thrombocytopenia

Warkentin

2019

Int J Lab Hematology

114

160

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Heparin‐induced thrombocytopenia (HIT) is a clinical‐pathological disorder; thus, laboratory testing for the pathogenic platelet‐activating antiplatelet factor 4 (PF4)/heparin antibodies is central for diagnosis. The “iceberg” model summarizes the inter‐relationship between platelet activation assays and PF4‐dependent immunoassays, with platelet‐activating antibodies comprising a subset of anti‐PF4/heparin antibodies. The platelet serotonin‐release assay (SRA), performed by reference laboratories, has high sensitivity and specificity for HIT (~95% each), and is especially suited for detecting highly pathogenic HIT sera containing both heparin‐dependent and heparin‐independent platelet‐activating antibodies; this latter subgroup of antibodies explains “autoimmune HIT” disorders (delayed‐onset, persisting, spontaneous, heparin “flush,” fondaparinux‐associated). Recently, SRA‐negative HIT has become recognized, in which serum from some HIT patients contains subthreshold levels of platelet‐activating antibodies (by SRA) that become detectable using a PF4‐enhanced platelet activation assay. Unusual immunologic features of HIT include early antibody detectability (at onset of platelet count fall) and antibody transience (seroreversion). Widely available PF4‐dependent enzyme immunoassays (EIAs) have high sensitivity but poor specificity for HIT, although specificity is enhanced with IgG‐specific EIAs and strong positive results; unfortunately, EIA results are usually not available in real time. Automated rapid immunoassays, such as the chemiluminescence immunoassay (CLIA) and latex immunoturbidimetric assay (LIA), facilitate real‐time laboratory diagnosis. Recently available likelihood ratio (LR) data for positive (LR+) and negative (LR−) test results allow clinicians to adjust their pretest probabilities for HIT, using Bayesian analysis, into real‐time posttest probabilities that are dramatically increased (test positive) or decreased (test negative). Moreover, (semi‐)quantitative CLIA‐ and LIA‐positive results (weak, moderate, strong positive) can further refine the posttest probability of HIT.

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Section: Pf4‐dependent Immunoassaysmentioning

confidence: 99%

Laboratory diagnosis of heparin‐induced thrombocytopenia

Warkentin

2019

Int J Lab Hematology

114

160

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“…We now report the results of our analysis involving the sensitivity and specificity of the PIFA in all English language studies reported to date, [10][11][12][13][14][15] along with a recent study evaluating a modified PIFA, the PIFA PLUSS. 16 (The PIFA PLUSS includes a seraSTAT Rapid Blood Cell Separator, allowing for testing of whole blood, rather than serum. 16 ) Prompted by a recent report, 17 we also obtained a report on the results of proficiency testing for the PIFA.…”

mentioning

confidence: 99%

“…16 (The PIFA PLUSS includes a seraSTAT Rapid Blood Cell Separator, allowing for testing of whole blood, rather than serum. 16 ) Prompted by a recent report, 17 we also obtained a report on the results of proficiency testing for the PIFA. Details regarding our systematic review and data synthesis are provided in a supplemental file which includes a PRISMA Flow Diagram ( Figure S1 in Appendix S1) and a QUADAS-2 assessment of study quality (Table S1 in Appendix S1).…”

mentioning

confidence: 99%

“…Overall estimates of PIFA sensitivity and specificity were obtained by jointly synthesizing the data from all seven studies using a bivariate random effects model for meta-analysis of diagnostic test data, which accommodates study heterogeneity. 20 Second, for those studies that evaluated samples by both the PIFA and an EIA, 10,11,13,16 we constructed 2 × 2 tables by cross-classifying samples according to the two methods. We then assessed the level of agreement between the two assays using Cohen's kappa statistic along with associated 95% CIs.…”

mentioning

confidence: 99%

“…15 All estimated sensitivities were below 0.714, corresponding to values too low for an acceptable screening test; further, no analysis showed an estimated specificity greater than 0.575. Figure 1B shows those studies 10,11,13,16 that permit comparison of PIFA reactivity vs an EIA. None of the five studies yielded CIs demonstrating improvement over chance agreement.…”

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confidence: 99%

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Limitations of the particle immunofiltration assay test for diagnosis of heparin‐induced thrombocytopenia

2020

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Heparin-induced thrombocytopenia (HIT) is an immune-mediated disorder caused by platelet-activating antibodies that recognize complexes of (cationic) platelet factor 4 (PF4) bound to heparin or certain other polyanions. 1 Laboratory testing for the pathogenic "HIT antibodies" has focused on platelet activation assays (eg, serotonin-release assay [SRA] 2 ; heparin-induced platelet activation assay [HIPA]) 3 and PF4-dependent enzyme-immunoassays (EIAs). 4,5 However, assay

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Diagnosis and management of heparin‐induced thrombocytopenia: Third edition

Arachchillage,

Thachil,

Anderson

et al. 2023

Br J Haematol

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This guideline was compiled according to the BSH process at (https:// b-s-h. org. uk/ media/ 16732/ bsh-guida nce-devel opmen t-proce ss-dec-5-18. pdf). The Grading of Recommendations Assessment, Development and Evaluation (GRADE) nomenclature was used to evaluate levels of evidence and to assess the strength of recommendations. The GRADE criteria can be found at http:// www. grade worki nggro up. org. A literature search was carried out using the terms given in Appendix until August 2022.

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PIFA PLUSS P4 Assay for Screening of Heparin-Induced Thrombocytopenia

Abstract: Despite its appealing feature of yielding rapid results, the PIFA assay is inadequate as a sole screening test for HIT because of its high probability of missing many true cases of HIT.

Cited by 4 publications

References 13 publications

Laboratory diagnosis of heparin‐induced thrombocytopenia

Laboratory diagnosis of heparin‐induced thrombocytopenia

Limitations of the particle immunofiltration assay test for diagnosis of heparin‐induced thrombocytopenia

Diagnosis and management of heparin‐induced thrombocytopenia: Third edition

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