Timely diagnosis and management of heparin‐induced thrombocytopenia in a frequent request, low incidence single centre using clinical 4T’s score and particle gel immunoassay

Bryant, Adam; Low, Joyce; Austin, Steven; Joseph, Joanne

doi:10.1111/j.1365-2141.2008.07401.x

Cited by 72 publications

(84 citation statements)

References 9 publications

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“…30 The positive predictive value of the 4Ts score was as low as 15.4%, a value less than the previously reported range from 21.4% to 100%. [8][9][10]15,[22][23][24][25][26] The false-positive rate of the 4Ts score (percentage of "4T high score" patients in the non-HIT patients) was 11.8%, a value comparable to those previously reported (0-15.3%). [8][9][10]15,[22][23][24][25][26] In contrast, the false-negative rate of the 4Ts scores (percentage of "4T low score" patients in HIT patients) was 54.5% (6/11), a value considerably higher than those previously reported (0-25%).…”

Section: Discussionsupporting

confidence: 78%

“…[8][9][10]15,[22][23][24][25][26] The false-positive rate of the 4Ts score (percentage of "4T high score" patients in the non-HIT patients) was 11.8%, a value comparable to those previously reported (0-15.3%). [8][9][10]15,[22][23][24][25][26] In contrast, the false-negative rate of the 4Ts scores (percentage of "4T low score" patients in HIT patients) was 54.5% (6/11), a value considerably higher than those previously reported (0-25%). [8][9][10]15,[22][23][24][25][26] These findings suggested that many individuals might develop HIT even with a low 4Ts score.…”

Section: Discussionsupporting

confidence: 78%

“…9 High negative predictive values ranging from 91.4% to 100% have been reported in subsequent studies carried out in medical-surgical ICU patients and cardiothoracic surgical patients. [8][9][10]15,[22][23][24][25][26] In the present study, a high negative predictive value of 4Ts score, 87.5%, was obtained for HIT, similarly to the previous studies mentioned above. This value was still lower than the values ranging from 91.4% to 100% in previous reports.…”

Section: Discussionsupporting

confidence: 76%

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Relationship between the 4Ts scoring system and the antiplatelet factor 4/heparin antibodies test in critically ill patients

Matsumura

Nakada

Oda

2013

Acute Medicine & Surgery

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Aim: Heparin-induced thrombocytopenia (HIT) is an adverse drug reaction and potentially progresses to fatal thrombosis. The 4Ts scoring system has been reported as a clinical pretest for HIT. However, its usefulness in critically ill patients has not yet been thoroughly examined. Thus, we evaluated the clinical usefulness of the 4Ts score in the diagnosis of HIT in critically ill patients. Methods:One hundred and four critically ill patients who were admitted to our intensive care unit and who underwent the antiplatelet factor 4/heparin complex antibodies (PF4/heparin Ab) test with suspected HIT were enrolled in the study. The primary endpoint variable was the 4Ts score. The secondary endpoint variables were laboratory data, length of stay, and mortality, compared between thePF4/ heparin Ab positive and negative groups.Results: There was no significant difference in the 4Ts scores between the PF4/heparin Ab positive and negative groups. The positive predictive value (HIT patients/4T high score patients) was 15.4% (2/13), the negative predictive value (non-HIT patients/4T low score patients) was 87.5% (42/48), and the false-negative rate for the 4Ts score (4T low score patients/HIT patients) was as high as 54.5% (6/11). The PF4/heparin Ab positive patients had longer stay in intensive care compared to the PF4/heparin Ab negative patients (P = 0.035). Conclusions:The present study showed the discrepancy between the 4Ts score and PF4/heparin Ab. When HIT is suspected in critically ill patients, an immediate HIT antibody test and initiation of therapeutic management of HIT are required regardless of the 4Ts score.

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Section: Discussionsupporting

confidence: 78%

Section: Discussionsupporting

confidence: 78%

Section: Discussionsupporting

confidence: 76%

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Relationship between the 4Ts scoring system and the antiplatelet factor 4/heparin antibodies test in critically ill patients

Matsumura

Nakada

Oda

2013

Acute Medicine & Surgery

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“…Only studies evaluating a clinical score and/or an IA with HIT diagnosis based on SRA as the gold standard were considered. The sensitivity and specificity (95% CI) of the Ô4 TsÕ probability score and the IA were then reassessed by incorporating the diagnostic performance of SRA reported by Cuker et al [4]; referred to as revisited sensitivity and specificity.Five studies evaluating a clinical score (4 Ts) [6-10] and three studies evaluating an IA were included [6,8,10]. In all of these studies but one [9], HIT was diagnosed if serotonin release was > 20% with 0.1 U mL )1 heparin and < 20%…”

mentioning

confidence: 99%

“…Five studies evaluating a clinical score (4 Ts) [6-10] and three studies evaluating an IA were included [6,8,10]. In all of these studies but one [9], HIT was diagnosed if serotonin release was > 20% with 0.1 U mL )1 heparin and < 20%…”

mentioning

confidence: 99%

Experts’ opinion or the serotonin release assay as a gold standard for the diagnosis of heparin‐induced thrombocytopenia (HIT)?

Tardy

Presles

Akrour

et al. 2011

Journal of Thrombosis and Haemostasis

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Heparin-induced thrombocytopenia (HIT) is a worrisome adverse drug reaction, widely thought to be caused by plateletactivating antibodies reactive against complexes between heparin and chemokines, most often but not always platelet factor 4 (PF4). HIT is challenging to diagnose clinically, as the cardinal clinical features of HIT, thrombocytopenia and thromboembolism in the setting of a proximate heparin exposure, are common findings among hospitalized patients for whom other plausible explanations exist [1]. Two types of assay are available for laboratory detection of HIT antibodies. Immunoassays (IAs) detect the presence of antibodies directed towards PF4-heparin complexes, whereas functional assays aim at detecting heparin-dependent platelet activation induced by these antibodies. While IAs are sensitive for detecting anti-PF4-heparin antibodies, although they do not detect antibodies directed against other chemokines than PF4 [2], their major drawback is a poor specificity as many patients exposed to heparin develop anti-PF4-heparin antibodies detectable by IA in the absence of HIT [3]. Platelet activation assays such as the platelet serotonin release assay (SRA) detect heparin-dependent antibodies that can bind to and activate platelets via their Fc gamma receptors. The reported sensitivity and specificity of SRA are up to 100% and 97%, respectively, for UFH-and LMWH-treated patients [4]. In many studies regarding patients with a clinical suspicion of HIT, SRA is used as the Ôgold standardÕ for HIT diagnosis. Recently, the diagnosis of HIT was for the first time based on the opinion of three independent experts [5] blinded to the results of both SRA (performed using the method described by Sheridan et al.) and IA. Surprisingly, it is reported in this study that both sensitivity and specificity of SRA were lower (71.4% [29-96.3] and 93% [80.9-98.5], respectively with 95% confidence intervals [CI]). So we looked at what would have been the results of previous studies that used SRA as the gold standard, had these revised SRA sensitivity and specificity values been used. We undertook a systematic review of all published validation studies for Ô4 TsÕ scores and IA HIT tests. The Medline database was used to find appropriate studies published during a 5-year period, from 2005 to 2010. Only studies evaluating a clinical score and/or an IA with HIT diagnosis based on SRA as the gold standard were considered. The sensitivity and specificity (95% CI) of the Ô4 TsÕ probability score and the IA were then reassessed by incorporating the diagnostic performance of SRA reported by Cuker et al. [4]; referred to as revisited sensitivity and specificity.Five studies evaluating a clinical score (4 Ts) [6-10] and three studies evaluating an IA were included [6,8,10]. In all of these studies but one [9], HIT was diagnosed if serotonin release was > 20% with 0.1 U mL )1 heparin and < 20%with 100 U mL )1 heparin. In one previous study [9], SRA was considered positive when serotonin release was > 50%. The sensitivity and specificit...

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Laboratory Evaluation of Heparin‐Induced Thrombocytopenia

Warkentin

Moore

2013

Quality in Laboratory Hemostasis and Thrombosis

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Timely diagnosis and management of heparin‐induced thrombocytopenia in a frequent request, low incidence single centre using clinical 4T’s score and particle gel immunoassay

Cited by 72 publications

References 9 publications

Relationship between the 4Ts scoring system and the antiplatelet factor 4/heparin antibodies test in critically ill patients

Relationship between the 4Ts scoring system and the antiplatelet factor 4/heparin antibodies test in critically ill patients

Experts’ opinion or the serotonin release assay as a gold standard for the diagnosis of heparin‐induced thrombocytopenia (HIT)?

Laboratory Evaluation of Heparin‐Induced Thrombocytopenia

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