PF4/Heparin Antibody Testing and Treatment of Heparin-Induced Thrombocytopenia in the Intensive Care Unit

Wanat, Matthew A.; Fitousis, Kalliopi; Hall, Jeff; Rice, Lawrence

doi:10.1177/1076029612438709

Cited by 12 publications

(4 citation statements)

References 21 publications

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“…In 2017, 1034 patients underwent anti‐PF4/H ELISA testing for HIT, reflecting a pretest probability for HIT of only 1.1% among tested patients. This 1.1% diagnosis rate is probably low because of ICD‐10 coding issues, but these data are consistent with previous studies showing that as many as 84% of patients who undergo ELISA testing for HIT have a 4Ts score of ≤ 3 . As these patients have a pretest probability of < 2% for HIT , few true‐positive test results occur.…”

Section: Discussionsupporting

confidence: 89%

A computerized scoring system to improve assessment of heparin‐induced thrombocytopenia risk

Gallo

Curry

Padilla-Jones

et al. 2019

Journal of Thrombosis and Haemostasis

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Current risk scores for heparin‐induced thrombocytopenia (HIT) are not computer‐friendly. We compared a new computerized risk score with the 4Ts score in a large healthcare system. The computerized risk score agrees with the 4Ts score 85% of the time. The new score could potentially improve HIT diagnosis via incorporation into decision support. Summary Background(HIT) is an immune‐mediated adverse drug event associated with life‐threatening thrombotic complications. The 4Ts score is widely used to estimate the risk for HIT and guide diagnostic testing, but it is not easily amenable to computerized clinical decision support (CDS) implementation. ObjectivesOur main objective was to develop an HIT computerized risk (HIT‐CR) scoring system that provides platelet count surveillance for timing and degree of thrombocytopenia to identify those for whom diagnostic testing should be considered. Our secondary objective was to evaluate clinical management and subsequent outcomes in those identified as being at risk for HIT. MethodsWe retrospectively analyzed data from a stratified sample of 150 inpatients treated with heparin to compare the performance of the HIT‐CR scoring system with that of a clinically calculated 4Ts score. We took a 4Ts score of ≥ 4 as the gold standard to determine whether HIT diagnostic testing should be performed. ResultsThe best cutoff point of the HIT‐CR score was a score of 3, which yielded 85% raw agreement with the 4Ts score and a kappa of 0.69 (95% confidence interval 0.57–0.81). Ninety per cent of patients with 4Ts score of ≥ 4 failed to undergo conventionally recommended diagnostic testing; 38% of these experienced persistent, unexplained thrombocytopenia, and 4% suffered life‐threatening thrombotic complications suggestive of undiagnosed HIT. ConclusionThe HIT‐CR scoring system is practical for computerized CDS, agrees well with the 4Ts score, and should be prospectively evaluated for its ability to identify patients who should be tested for HIT.

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Section: Discussionsupporting

confidence: 89%

A computerized scoring system to improve assessment of heparin‐induced thrombocytopenia risk

Gallo

Curry

Padilla-Jones

et al. 2019

Journal of Thrombosis and Haemostasis

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“…Clinical assessment is imperative when evaluating patients with suspected HIT. Previous literature has demonstrated that 45-84% of individuals who undergo laboratory assessment for HIT are low-risk based on pretest probability [14][15][16][17]. Among our individuals with ODs between 0.5 and 2, 96% had negative SRA Proportions of 4T score classification with escalating OD magnitude.…”

Section: Discussionmentioning

confidence: 66%

Analysis of heparin-induced thrombocytopenia diagnostic and management strategies in individuals with inconclusive antibody optical densities

Erich

Knutson

Barnes

2023

Blood Coagulation &Amp; Fibrinolysis

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Heparin-induced thrombocytopenia (HIT) is an uncommon but serious complication of exposure to heparin. Antibody optical densities (ODs) used to diagnose HIT exceeding 2 are highly suggestive of disease, whereas ODs less than 0.5 often ‘rule out’ HIT. Variation in the clinical care of patients with inconclusive ODs between 0.5 and 2 is likely. This single-centre, retrospective analysis evaluates the diagnosis, management and outcomes of those with antibody ODs between 0.5 and 2. We queried our institution's Healthcare Enterprise Repository for Ontological Narration (HERON) database to identify individuals with antibody ODs between 0.5 and 2. Chart review was completed to calculate 4T scores, corroborate diagnosis codes with documented information in our electronic health record (EHR) and evaluate the diagnosis, management and outcomes of these individuals. These data were evaluated using descriptive and univariate statistics. Among individuals evaluated for HIT between November 2007 and July 2020, we identified 302 individuals with ODs between 0.5 and 2. Serotonin release assays (SRAs) were assessed in 55% (165/302) and were positive in 12% (20/165). In those with available data, 96% with low 4T scores had negative SRAs and 4% had positive SRAs. As 4T scores and antibody ODs proportionally increased, SRA positivity also increased. Clinical management varied widely; however, 4T scoring remains a valuable assessment in this cohort. In those with HIT antibody ODs between 0.5 and 2, true positives were uncommon, and their clinical management varied widely. Fortunately, 4T scoring is a useful prognostic tool that improves the diagnosis and management among those with inconclusive HIT.

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“…Additionally, the positive predictive value of positive PF4/heparin IgG ELISA was also low. These tests often detect antibodies, which may not necessarily be the cause of the clinical symptoms of HIT [ 24 , 25 ]. Therefore, even with careful application of the 4 T score and HIT ELISA testing, a subsequent platelet activation assay is indispensable to prove or rule out HIT in critically ill patients.…”

Section: Discussionmentioning

confidence: 99%

Argatroban versus Lepirudin in critically ill patients (ALicia): a randomized controlled trial

et al. 2014

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IntroductionCritically ill patients often require renal replacement therapy accompanied by thrombocytopenia. Thrombocytopenia during heparin anticoagulation may be due to heparin-induced thrombocytopenia with need for alternative anticoagulation. Therefore, we compared argatroban and lepirudin in critically ill surgical patients.MethodsFollowing institutional review board approval and written informed consent, critically ill surgical patients more than or equal to 18 years with suspected heparin-induced thrombocytopenia, were randomly assigned to receive double-blind argatroban or lepirudin anticoagulation targeting an activated Partial Thromboplastin Time (aPTT) of 1.5 to 2 times baseline. In patients requiring continuous renal replacement therapy we compared the life-time of hemodialysis filters. We evaluated in all patients the incidence of bleeding and thrombembolic events.ResultsWe identified 66 patients with suspected heparin-induced thrombocytopenia, including 28 requiring renal replacement therapy. Mean filter lifetimes did not differ between groups (argatroban 32 ± 25 hours (n = 12) versus lepirudin 27 ± 21 hours (n = 16), mean difference 5 hours, 95% CI −13 to 23, P = 0.227). Among all 66 patients, relevant bleeding occurred in four argatroban- versus eleven lepirudin-patients (OR 3.9, 95% CI 1.1 to 14.0, P = 0.040). In the argatroban-group, three thromboembolic events occurred compared to two in the lepirudin group (OR 0.7, 95% CI 0.1 to 4.4, P = 0.639). The incidence of confirmed heparin-induced thrombocytopenia was 23% (n = 15) in our study population.ConclusionsThis first randomized controlled double-blind trial comparing two direct thrombin inhibitors showed comparable effectiveness for renal replacement therapy, but suggests fewer bleeds in surgical patients with argatroban anticoagulation.Trial registrationClinical Trials.gov NCT00798525. Registered 25 November 2008Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-014-0588-8) contains supplementary material, which is available to authorized users.

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PF4/Heparin Antibody Testing and Treatment of Heparin-Induced Thrombocytopenia in the Intensive Care Unit

Abstract: In critically ill patients, low 4Ts scores indicate a low probability of HIT, and heparin antibody testing in these patients is not useful.

Cited by 12 publications

References 21 publications

A computerized scoring system to improve assessment of heparin‐induced thrombocytopenia risk

A computerized scoring system to improve assessment of heparin‐induced thrombocytopenia risk

Analysis of heparin-induced thrombocytopenia diagnostic and management strategies in individuals with inconclusive antibody optical densities

Argatroban versus Lepirudin in critically ill patients (ALicia): a randomized controlled trial

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