Evaluation of Serotonin Release Assay and Enzyme-Linked Immunosorbent Assay Optical Density Thresholds for Heparin-Induced Thrombocytopenia in Patients on Extracorporeal Membrane Oxygenation

2020 ◽  
Vol 48 (2) ◽  
pp. e82-e86
Author(s):  
Vivek Kataria ◽  
Leanne Moore ◽  
Sarah Harrison ◽  
Omar Hernandez ◽  
Nathan Vaughan ◽  
...  
Keyword(s):  
Extracorporeal Membrane Oxygenation ◽  
Optical Density ◽  
Immunosorbent Assay ◽  
Serotonin Release ◽  
Enzyme Linked Immunosorbent Assay ◽  
Heparin Induced Thrombocytopenia ◽  
Membrane Oxygenation ◽  
Release Assay

scholarly journals Comparison of an IgG-Specific Enzyme-Linked Immunosorbent Assay Cutoff of 0.4 Versus 0.8 and 1.0 Optical Density Units for Heparin-Induced Thrombocytopenia

2016 ◽  
Vol 23 (3) ◽  
pp. 282-286 ◽  
Author(s):  
Brianne M. Ritchie ◽  
Jean M. Connors ◽  
Katelyn W. Sylvester
Keyword(s):  
Optical Density ◽  
Immunosorbent Assay ◽  
Predictive Value ◽  
Retrospective Chart Review ◽  
Serotonin Release ◽  
Enzyme Linked Immunosorbent Assay ◽  
Platelet Factor ◽  
Heparin Induced Thrombocytopenia ◽  
Institutional Review ◽  
Sensitivity Specificity

Background: Previous studies have demonstrated optimized diagnostic accuracy in utilizing higher antiheparin–platelet factor 4 (PF4) enzyme-linked immunosorbent assay (ELISA) optical density (OD) thresholds for diagnosing heparin-induced thrombocytopenia (HIT). We describe the incidence of positive serotonin release assay (SRA) results, as well as performance characteristics, for antiheparin–PF4 ELISA thresholds ≥0.4, ≥0.8, and ≥1.0 OD units in the diagnosis of HIT at our institution. Methods: Following institutional review board approval, we conducted a single-center retrospective chart review on adult inpatients with a differential diagnosis of HIT evaluated by both antiheparin–PF4 ELISA and SRA from 2012 to 2014. The major endpoints were to assess incidence of positive SRA results, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy at antiheparin–PF4 ELISA values ≥0.4 OD units when compared to values ≥0.8 and ≥1.0 OD units. Clinical characteristics, including demographics, laboratory values, clinical and safety outcomes, length of stay, and mortality, were collected. Results: A total of 140 patients with 140 antiheparin–PF4 ELISA and SRA values were evaluated, of which 23 patients were SRA positive (16.4%) and 117 patients were SRA negative (83.6%). We identified a sensitivity of 91.3% versus 82.6% and 73.9%, specificity of 61.5% versus 87.2% and 91.5%, PPV of 31.8% versus 55.9% and 63.0%, NPV of 97.3% versus 96.2% and 94.7%, and accuracy of 66.4% versus 86.4% and 88.6% at antiheparin–PF4 ELISA thresholds ≥0.4, ≥0.8, and ≥1.0 OD units, respectively. Conclusion: Our study suggests an increased antiheparin–PF4 ELISA threshold of 0.8 or 1.0 OD units enhances specificity, PPV, and accuracy while maintaining NPV with decreased sensitivity.

scholarly journals Heparin-induced thrombocytopenia in patients on extracorporeal membrane oxygenation and the role of a heparin-bonded circuit

Perfusion ◽  
2019 ◽  
Vol 34 (7) ◽  
pp. 584-589 ◽  
Author(s):  
Dirk Pabst ◽  
Jacqueline B Boone ◽  
Behzad Soleimani ◽  
Christoph E Brehm
Keyword(s):  
Overall Survival ◽  
Platelet Count ◽  
Retrospective Study ◽  
Extracorporeal Membrane Oxygenation ◽  
Serotonin Release ◽  
Single Center ◽  
Heparin Induced Thrombocytopenia ◽  
Membrane Oxygenation ◽  
Release Assay

Background: In patients supported with extracorporeal membrane oxygenation, and who develop heparin-induced thrombocytopenia, there is no clear evidence to support changing to a non-heparin-coated extracorporeal membrane oxygenation circuit. Our goal was to evaluate clinical outcomes of patients who were continued on heparin-bonded circuits despite diagnosed heparin-induced thrombocytopenia. Methods: We completed a single-center retrospective study of all patients who underwent extracorporeal membrane oxygenation support from July 2008 to July 2017 and were tested heparin-induced thrombocytopenia positive while on extracorporeal membrane oxygenation support. After diagnosis of heparin-induced thrombocytopenia, mean platelet count (k/µL) was measured on consecutive days for 14 days. Results: Out of 455 patients, 14 (3.1%) had a diagnosis of heparin-induced thrombocytopenia by serotonin release assay and systemic heparin treatment was discontinued in every case. In total, 11 of the heparin-induced thrombocytopenia patients (78.6%) survived to discharge. The overall survival of all 455 extracorporeal membrane oxygenation patients was 54.1%. Platelets counts after discontinuation of systemic heparin in the heparin-induced thrombocytopenia patients increased from a mean of 59.8 k/µL at time of heparin-induced thrombocytopenia diagnosis to a mean of 280.2 k/µL at 14 days after discontinuation of heparin despite continuation of the heparin-bonded circuit. Platelet count increased in heparin-induced thrombocytopenia patients on extracorporeal membrane oxygenation support after discontinuation of systemic heparin even if maintained on the heparin-bonded circuit. Conclusion: Discontinuation of systemic heparin but continuation of heparin-coated extracorporeal membrane oxygenation circuits appeared to be an appropriate response for our extracorporeal membrane oxygenation–supported patients who developed heparin-induced thrombocytopenia. Survival in this group was not significantly different to those patients on extracorporeal membrane oxygenation without heparin-induced thrombocytopenia. Larger studies should evaluate the safety of heparin-bonded extracorporeal membrane oxygenation systems in heparin-induced thrombocytopenia patients.

scholarly journals Clinical Significance of the Serotonin Release Assay and Platelet Count Monitoring After Cardiac Surgery

2017 ◽  
Vol 24 (6) ◽  
pp. 944-949 ◽  
Author(s):  
Shinya Motohashi ◽  
Takefumi Matsuo ◽  
Hidenori Inoue ◽  
Makoto Kaneko ◽  
Shunya Shindo
Keyword(s):  
Cardiac Surgery ◽  
Platelet Count ◽  
Clinical Course ◽  
Serotonin Release ◽  
Enzyme Linked Immunosorbent Assay ◽  
Heparin Induced Thrombocytopenia ◽  
Release Assay ◽  
Immunological Assays ◽  
Platelet Count Monitoring ◽  
The Relationship

Heparin-induced thrombocytopenia (HIT) is one of the serious complications in patients who undergo cardiac surgery. However, there remains a major problem in diagnosing HIT because the current immunological assays for detection of HIT antibody have limitations. Furthermore, the clinical course of thrombocytopenia in this surgery makes it increasingly difficult to diagnose HIT. We investigated the relationship between platelet count and HIT antibody in 59 patients who underwent cardiac surgery using cardiopulmonary bypass (CPB). The number of postoperative HIT antibody-positive patients evaluated using enzyme-linked immunosorbent assay kit (polyanion IgG/IgA/IgM complex antibodies/antiplatelet factor 4 enhanced) was 37 (62.7%). In contrast, platelet activation by HIT antibody was evaluated using the serotonin release assay (SRA). More than 20% and 50% release of serotonin was obtained from 12 patients (20.3%) and 8 patients (13.6%), respectively. The levels of d-dimer were significantly different on postoperative day 14 between SRA-positive and SRA-negative groups; however, postoperative thrombus complication was not detected using sonography in the patients with positive serotonin release at all. After being decreased by the operation, their platelet count recovered within 2 weeks in both groups equally. In our study, although the patients were positive in the platelet activating HIT antibody assay, they remained free from thrombosis and their platelet count recovered after early postoperative platelet decrease. Therefore, in addition to the SRA, monitoring of platelet count might be still considered an indispensable factor to facilitate the prediction of HIT thrombosis prior to manifestation in the patients undergoing cardiac surgery using CPB.

Predictive value of scoring tools in determining heparin-induced thrombocytopenia in patients on extracorporeal membrane oxygenation

Perfusion ◽  
2019 ◽  
Vol 35 (5) ◽  
pp. 378-383 ◽  
Author(s):  
Jaclyn Sullivan ◽  
Erica Bak ◽  
Mary Jane Sullivan ◽  
Payal K. Gurnani
Keyword(s):  
Extracorporeal Membrane Oxygenation ◽  
Predictive Value ◽  
Medical Center ◽  
High Sensitivity ◽  
Serotonin Release ◽  
Heparin Induced Thrombocytopenia ◽  
Membrane Oxygenation ◽  
Observational Cohort ◽  
Post Cardiopulmonary Bypass ◽  
Scoring Tools

There are currently no scoring tools validated for use in predicting heparin-induced thrombocytopenia in patients receiving extracorporeal membrane oxygenation. This study aims to determine the predictive value of the Warkentin 4T score, Lilo-Le Louet score, and the heparin-induced thrombocytopenia expert probability score in detecting heparin-induced thrombocytopenia in patients on extracorporeal membrane oxygenation. This was a single center, retrospective, observational cohort study of patients at Rush University Medical Center. Heparin-induced thrombocytopenia–positive patients were defined as those with an optical density greater than or equal to 0.4, consistent with a positive anti-platelet 4 heparin antibody. Out of 39 patients on extracorporeal membrane oxygenation with suspected heparin-induced thrombocytopenia, six (15.4%) were found to be anti-platelet 4–positive. A heparin-induced thrombocytopenia diagnosis was confirmed by serotonin-release assay in two patients (5.1%). The 4T, heparin-induced thrombocytopenia expert probability, and Lilo-Le Louet scoring tools all demonstrated a low positive predictive value (21.4%, 16.7%, and 6.7%, respectively), with the 4T and heparin-induced thrombocytopenia expert probability scores demonstrating the highest specificity (66.7% and 84.8%, respectively) and lowest sensitivity (50% and 16.7%, respectively). The Lilo-Le Louet score had high sensitivity (100%) and low specificity (12.5%) in post-cardiopulmonary bypass patients. Based on the findings of this study, all three scoring tools have limited utility for predicting heparin-induced thrombocytopenia in patients on extracorporeal membrane oxygenation.

Serologic Results in >1000 Patients With Suspected Heparin-Induced Thrombocytopenia

2007 ◽  
Vol 14 (4) ◽  
pp. 410-414 ◽  
Author(s):  
Suresh G. Shelat ◽  
Anne Tomaski ◽  
Eleanor S. Pollak
Keyword(s):  
Laboratory Diagnosis ◽  
Serotonin Release ◽  
Enzyme Linked Immunosorbent Assay ◽  
Functional Assay ◽  
Platelet Factor ◽  
Heparin Induced Thrombocytopenia ◽  
Life Threatening ◽  
Release Assay ◽  
Pathogenic Antibodies

Heparin-induced thrombocytopenia (HIT) can lead to life-threatening and limb-threatening thrombosis. HIT is thought to be initiated by the interaction of pathogenic antibodies toward a complex platelet factor 4 (PF4) and heparin (PF4:H), which can activate platelets and predispose to thrombosis. As such, the laboratory diagnosis of HIT includes antigenic and functional assays to detect antibodies directed at PF4:H complexes. We performed a retrospective analysis of 1017 consecutive samples tested by serotonin-release assay and by enzyme-linked immunosorbent assay (ELISA). Most samples showed no serologic evidence of HIT, whereas 4% to 5% of samples demonstrated both antigenic and functional serological evidence for HIT. Approximately 12% to 18% of samples showed immunologic evidence of anti-PF4:H antibodies but without functional evidence of serotonin release in vitro. Interestingly, a small minority of samples (0.7%) caused serotonin release but were negative in the ELISA. The results are presented using cutoff values established at our hospital and for the ELISA manufacturer. This study provides a pretest probability of the serologic results from an antigenic assay (ELISA) and a functional assay (serotonin-release assay) in patients clinically suspected of having HIT.

Correlation Of Heparin Confirmatory Test (HCT) With Optical Density (OD) and Serotonin Release Assay (SRA) In The Diagnosis Of Heparin Induced Thrombocytopenia (HIT)

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4754-4754 ◽  
Author(s):  
Ravneet Thind ◽  
Danielle Heidemann ◽  
Sundara Raman ◽  
Philip Kuriakose
Keyword(s):  
Optical Density ◽  
Predictive Value ◽  
Serotonin Release ◽  
Thrombin Inhibitors ◽  
Confirmatory Test ◽  
Functional Assay ◽  
Heparin Induced Thrombocytopenia ◽  
Laboratory Confirmation ◽  
Confirmation Test ◽  
Release Assay

Introduction Heparin-induced thrombocytopenia (HIT) is a potentially fatal, thrombotic complication of heparin therapy mediated by antibodies to complexes between platelet factor 4 (PF4) and heparin. Accurate and rapid diagnosis with prompt commencement of therapy are imperative as delays in treatment are associated with an increasing risk of thrombosis, amputation, or death. On the flip side, initiation of therapy with direct thrombin inhibitors without laboratory confirmation carries a significant risk of bleeding. Two types of laboratory tests are available for detection of these antibodies: a widely available immunoassay (ELISA), which is very sensitive to the presence of anti-heparin/PF4 antibodies, but is less specific to the clinical syndrome of HIT because of detection of non-pathological antibodies. The Serotonin Release Assay (SRA) is a functional assay that is now considered the gold standard for confirmatory diagnosis of HIT due to its high specificity. However, the downside of SRA is the cost involved, limited availability and a turnaround time of 5-7 days. As such, a heparin confirmatory test (HCT) with excess heparin has been in use since mid 2011 on positive ELISA samples in our laboratory to improve test specificity. This test is more cost and time efficient, with a turnover time of no more than 48 hours. As noted in prior studies, inhibition of a positive ELISA result by 50% or more in the presence of excess heparin is considered confirmatory of heparin-dependent antibodies. Likewise a negative confirmatory test is defined as a decrease of 50% or less in antibody binding in the presence of heparin. Aim a) Correlation of Heparin Confirmatory test (HCT) with strength of HIT ELISA, vis-à-vis optical density (OD) of 0.4 - 0.99 and OD of >/= 1.0. b) Correlation of HCT results with SRA, to see if the latter can be replaced by the heparin confirmatory test. Patients and Methods A retrospective chart review of adult patients hospitalized at our institution with suspected HIT from July 2011 until January 2013 was done. There were 101 such patients. All patients who had a positive HIT ELISA, then had HCT as per our standard lab practice, with an SRA test done for diagnosis/confirmation of HIT, as per standard clinical practice. Historically, the major strength of SRA assay is its specificity. The optical density on HIT ELISA and SRA results were then compared with the Heparin Confirmatory test to establish clinical significance. Results Of the 101 patients tested for HIT ELISA, 49 were positive. HCT and SRA were performed on all 49 samples, 1 out of which was reported as indeterminate. Hence 48 samples were used for primary analysis, comparing HCT to the OD as well as the SRA results. Out of 48 patients, 6 had positive SRA with Heparin inhibition of >50% (sensitivity 6/6 = 100%). Remaining 42 patients had negative SRA, 7 out of which had Heparin inhibition of <50% (specificity 7/42 = 16.6%). All 7 patients with a negative HCT had a negative SRA, making the negative predictive value of the HCT 100%; however positive predictive value was only 14.6% (6/41). There was no correlation between the OD and Heparin Confirmation test. Conclusions Although there is data suggesting that there might be some value to the Heparin Confirmation test, we were unable to show a significant correlation between HCT and OD or between HCT and SRA. The prospect of having a cost effective and rapid assay for laboratory confirmation of HIT will always be a relevant need. We feel that a larger, prospective study should be conducted to definitively assess the relationship between HCT and SRA. Disclosures: No relevant conflicts of interest to declare.

Prevalence and Overtesting of True Heparin-Induced Thrombocytopenia in a 591-Bed Tertiary Care, Teaching Hospital

2017 ◽  
Vol 34 (6) ◽  
pp. 464-471 ◽  
Author(s):  
Stephen Farley ◽  
Caitlyn Cummings ◽  
William Heuser ◽  
Shan Wang ◽  
Rose Calixte ◽  
...  
Keyword(s):  
New York ◽  
Tertiary Care ◽  
Retrospective Chart Review ◽  
Elisa Test ◽  
Serotonin Release ◽  
University Hospital ◽  
Enzyme Linked Immunosorbent Assay ◽  
Heparin Induced Thrombocytopenia ◽  
Release Assay ◽  
Hospital Stays

Heparin-induced thrombocytopenia type II (HIT) is a rare but potentially fatal antibody-mediated reaction to all forms of heparin (unfractionated heparin, low-molecular weight heparin, heparin flushes, and heparin-coated catheters), which can lead to HIT with thrombosis. Two tests commonly used to screen for HIT include the enzyme-linked immunosorbent assay (ELISA) and serotonin release assay (SRA). This is a retrospective chart review study conducted from January 1, 2013, through December 31, 2014, to estimate the rate of true HIT in critical care patients at Winthrop-University Hospital, located in Mineola, New York. Patients are classified as positive for HIT if both ELISA and SRA immunoassays are positive. We reviewed 507 heparin immunoassays, excluding 64 who had an inappropriate ELISA test sent due to no administration of heparin, enoxaparin, or heparin lock flush at this or previous hospital stays at Winthrop. Of the 443 heparin immunoassays, ELISA results were positive for 66 patients (15.1%), and only 11 (2.5%) patients had true cases of HIT with a 95% confidence interval of 1.3% to 4.4%. The 4T score for those with true HIT (median: 5.0) was statistically higher compared to those without true HIT (median: 2.0; P < .001). Despite guidelines in place, overtesting for HIT is still a prevalent issue.

scholarly journals Risk of Subsequent Thrombosis in Patients with Isolated Heparin-Induced Thrombocytopenia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3566-3566
Author(s):  
Heather R Wolfe ◽  
Yu-Min Shen
Keyword(s):  
Optical Density ◽  
Thrombotic Event ◽  
Serotonin Release ◽  
Short Term ◽  
Heparin Induced Thrombocytopenia ◽  
Significant Difference ◽  
Thrombotic Complications ◽  
Release Assay ◽  
Prophylactic Anticoagulation

Abstract Background: Heparin-Induced Thrombocytopenia (HIT) is one of the most important and commonly encountered immune-mediated drug reactions which can lead to significant morbidity and mortality. In up to 25% of patients, thrombosis can be the presenting finding of HIT. Isolated HIT occurs in patients without clinically evident thrombosis at the time of diagnosis. The management of HIT focuses on reducing the risk of thrombotic complications. In addition to prompt discontinuation of heparin products, anticoagulation is recommended. The risk of thrombosis is thought to remain high for up to 4 weeks due to persistent circulating PF4-heparin antibodies. Prior studies have shown that in patients with isolated HIT, the subsequent 30-day risk of thrombosis is up to 53%. Guidelines recommend 3 months of anticoagulation for patients with HIT-associated thrombosis. The optimal duration of anticoagulation in isolated HIT is unknown. Many experts recommend prophylactic anticoagulation for up to 4 weeks after diagnosis. However in the era of direct thrombin inhibitors, the need for prophylactic anticoagulation and risk of thrombosis beyond normalization of platelet count remains to be determined. The aim of this study was to determine the incidence of subsequent thrombosis in patients with isolated HIT. Methods: In this retrospective review, we identified patients with a documented positive HIT (heparin-PF4 antibody) enzyme immunoassay (ELISA) at our affiliated hospitals between January 2006 and December 2016. Laboratory data from these patients were reviewed. Patients who met criteria for HIT, defined as HIT ELISA optical density ≥ 2 or positive serotonin release assay were included in the analysis. From this cohort of patients with confirmed HIT, clinical data was extracted from the electronic medical record, including anticoagulation management and documented thrombotic events within 3 months of HIT diagnosis. Patients with evidence of thrombosis at the time of diagnosis were excluded in the final analysis as our focus was on patients with isolated HIT. The incidence of subsequent thrombosis was compared in patients who received anticoagulation versus those who did not receive anticoagulation. Results: A total of 403 charts were reviewed from patients with a documented positive HIT ELISA, defined as an optical density of > 0.4. Of the 403 patients, 49.5% (n = 107) met criteria for HIT, with an optical density > 2 or positive serotonin release assay. In patients with HIT, 48.6% (n = 52) did not have evidence of thrombosis at the time of diagnosis. Of these patients with isolated HIT, 14 patients (26.9%) received no prophylactic anticoagulation, 8 patients (15.4%) received prophylactic anticoagulation for at least 4 weeks but less than 3 months, and 30 patients (57.7%) were anticoagulated for 3 months or longer. The total incidence of subsequent thrombosis in isolated HIT was 7.7%. In the cohort of patients that did not receive prophylactic anticoagulation, two patients (14.3%) developed a thrombotic event in the 3 months following the HIT diagnosis. No documented thrombotic complications occurred in the eight patients that received prophylactic anticoagulation for at least 4 weeks but less than 3 months. Three patients (10%) who received long-term anticoagulation (≥3 months) developed a subsequent thrombotic event. There was no significant difference in the incidence of subsequent thrombosis in patients who did not receive prophylactic anticoagulation versus patients who received short-term prophylactic anticoagulation (p=0.141). In addition, there was no significant difference in the incidence of subsequent thrombosis in patients who did not receive prophylactic anticoagulation versus those who received long-term anticoagulation (p=0.701). Conclusions: The optimal duration of anticoagulation in patients with isolated HIT is unknown. Our incidence of thrombosis following the diagnosis of HIT was lower than previously described. Patients who did not receive prophylactic anticoagulation did not have a significantly higher incidence of thrombosis compared to patients who received short-term prophylactic or long-term anticoagulation. The study was limited by the retrospective nature and small sample size. Further studies are needed to better understand the ideal length of anticoagulation to prevent thrombotic complications without leading to unnecessary increased risk of bleeding. Disclosures No relevant conflicts of interest to declare.

scholarly journals Validation of the high-dose heparin confirmatory step for the diagnosis of heparin-induced thrombocytopenia

Blood ◽  
2010 ◽  
Vol 116 (10) ◽  
pp. 1761-1766 ◽  
Author(s):  
Nicole L. Whitlatch ◽  
David F. Kong ◽  
Ara D. Metjian ◽  
Gowthami M. Arepally ◽  
Thomas L. Ortel
Keyword(s):  
Optical Density ◽  
Immunosorbent Assay ◽  
Predictive Accuracy ◽  
Confirmatory Test ◽  
Brier Score ◽  
Multivariate Logistic Regression Model ◽  
Enzyme Linked Immunosorbent Assay ◽  
High Dose ◽  
Platelet Factor ◽  
Heparin Induced Thrombocytopenia

Abstract The diagnosis of heparin-induced thrombocytopenia (HIT) requires detection of antibodies to the heparin/platelet factor 4 (PF4) complexes via enzyme-linked immunosorbent assay. Addition of excess heparin to the sample decreases the optical density by 50% or more and confirms the presence of these antibodies. One hundred fifteen patients with anti-heparin/PF4 antibodies detected by enzyme-linked immunosorbent assay were classified as clinically HIT-positive or HIT-negative, followed by confirmation with excess heparin. A multivariate logistic regression model was fitted to estimate relationships between patient characteristics, laboratory findings, and clinical HIT status. This model was validated on an independent sample of 97 patients with anti-heparin/PF4 antibodies. No relationship between age, race, or sex and clinical HIT status was found. Maximal optical density and confirmatory positive status independently predicted HIT in multivariate analysis. Predictive accuracy on the training set (c-index 0.78, Brier score 0.17) was maintained when the algorithm was applied to the independent validation population (c-index 0.80, Brier score 0.20). This study quantifies the clinical utility of the confirmatory test to diagnose HIT. On the basis of data from the heparin/PF4 enzyme-linked immunosorbent assay and confirmatory assays, a predictive computer algorithm could distinguish patients likely to have HIT from those who do not.

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