Efficiency of Diagnosing HIT at a Large Academic Medical Center

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2059-2059
Author(s):  
Marcia N Paddock ◽  
Bryce Clark ◽  
Maria Teresa De Sancho
Keyword(s):  
Laboratory Testing ◽  
Conflicts Of Interest ◽  
Academic Medical Center ◽  
Tertiary Care ◽  
Screening Tools ◽  
High Morbidity ◽  
Reference Laboratory ◽  
Heparin Administration ◽  
Low Probability ◽  
4T Score

Abstract Background: Thrombocytopenia during heparin administration is common in hospitalized patients, leading to frequent testing for heparin-induced thrombocytopenia (HIT). The 4T score, which is based on degree and timing of thrombocytopenia, and whether there are other explanations for thrombocytopenia or the presence of thrombosis, is a commonly used tool to assess the clinical probability of HIT prior to performing laboratory testing. Published guidelines recommend further testing with an anti-PF4/heparin enzyme immunoassay (EIA) and confirmation with the serotonin-release assay (SRA) when the pretest probability of HIT is intermediate or high. The diagnosis of HIT confers high morbidity and mortality; therefore it is crucial to establish a definitive diagnosis in patients with suspected HIT. However, empiric treatment with alternative non-heparin anticoagulants increases the cost of hospitalization and may cause unnecessary risks in patients with a false positive EIA. The purpose of our study was to evaluate the utilization of EIA and SRA at a large tertiary care center and to assess the agreement between the 4T score, the EIA, and the SRA. Methods: We retrospectively reviewed all EIAs performed in our special hematology laboratory and SRAs sent to a reference laboratory at our institution in patients with suspected HIT between July 2012 and June 2014. First we evaluated the 4T score in all patients in whom laboratory testing was requested and subsequently assessed the correlation between the 4T score and the EIA and SRA results. A 4T score of 6 to 8 was high and a 4T score of 4 to 5 was intermediate. A strong positive EIA was defined as an EIA with an optical density (OD) of ≥ 1.00 and a weak/indeterminate EIA had an OD of 0.40-0.99. Results: A total of 583 unique PF4 EIAs were requested during the study period (Figure 1). Of these, 472 (81%) and 77 (13%) were performed in patients with intermediate/ high probability and with low-probability of HIT, respectively and in 34 patients (6%) the EIA was requested without documentation of the 4T score. Of the 472 patients with an intermediate or high 4T score, 36 (8%) had an EIA with an OD ≥ 1.0. Of these 36 patients, 27 (75%) had SRA performed and were positive in 14 patients (52%). Twenty-three (5%) of the 472 patients had a weakly positive EIA and in 18 (78%) of them the SRA was sent and were all negative. Five of the 472 patients (1%) had a positive SRA in the setting of an intermediate or high 4T score and a negative or indeterminate/weakly positive EIA. The SRA was sent in 24 patients with low probability 4T score (0-3) and in 9 patients with no documented 4T score. Two of these 33 (6%) patients had a positive SRA. Overall, the incidence of HIT based on a 4T score of 4 to 8, a positive EIA and positive SRA was found in 16 (3.4%) of the 472 patients; 2 of these 16 patients (12.5%) had a indeterminate/weakly positive EIA. Of the 216 SRAs sent, 21 were positive (9.7%). Patients with a lower pre-test probability based on a low or intermediate 4T score and negative/weakly positive EIA accounted for 33% of HIT cases observed. Patients with an intermediate/high 4T and strong or weakly positive EIA accounted for the remaining 67%. Conclusions: The incidence of definitive HIT in our study was low. There was a poor correlation between the 4T score and SRA positivity and between the EIA and SRA results. The combination of an intermediate/high 4T score and a strong EIA confirmed the diagnosis of HIT in only half of the patients. These findings underscore the need for improved screening tools for HIT. Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.

Physician Survey of a Laboratory Medicine Interpretive Service and Evaluation of the Influence of Interpretations on Laboratory Test Ordering

2004 ◽  
Vol 128 (12) ◽  
pp. 1424-1427 ◽  
Author(s):  
Martha E. Laposata ◽  
Michael Laposata ◽  
Elizabeth M. Van Cott ◽  
Dion S. Buchner ◽  
Mohammed S. Kashalo ◽  
...  
Keyword(s):  
Laboratory Testing ◽  
Medical Center ◽  
Academic Medical Center ◽  
Physician Satisfaction ◽  
Patient Specific ◽  
Diagnostic Process ◽  
Reference Laboratory ◽  
Academic Medical ◽  
Coagulation Testing ◽  
Test Ordering

Abstract Context.—Complex coagulation test panels ordered by clinicians are typically reported to clinicians without a patient-specific interpretive paragraph. Objectives.—To survey clinicians regarding pathologist-generated interpretations of complex laboratory testing panels and to assess the ability of the interpretations to educate test orderers. Design.—Surveys were conducted of physicians ordering complex coagulation laboratory testing that included narrative interpretation. Evaluation of order requisitions was performed to assess the interpretation's influence on ordering practices. Setting.—Physicians ordering coagulation testing at a large academic medical center hospital in Boston, Mass, and physicians from outside hospitals using the academic medical center as a reference laboratory for coagulation testing. Outcome Measures.—Physician surveys and evaluation of laboratory requisition slips. Results.—In nearly 80% of responses, the ordering clinicians perceived that the interpretive comments saved them time and improved the diagnostic process. Moreover, the interpretations were perceived by ordering clinicians to help prevent a misdiagnosis or otherwise impact the differential diagnosis in approximately 70% of responses. In addition, interpretations appeared to be able to train the ordering clinicians as to the standard ordering practices. Conclusions.—The results demonstrate physician satisfaction with an innovative information delivery approach that provides laboratory diagnostic interpretation and test-ordering education to clinicians in the context of their daily workflow.

scholarly journals Appropriate Laboratory Testing for Lupus Anticoagulants: An Observational Study at an Academic, Tertiary Care Hospital

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 27-28
Author(s):  
Henry Feng ◽  
Evelien Schaafsma ◽  
Lauren T. Salvatore ◽  
Deborah L. Ornstein
Keyword(s):  
Laboratory Testing ◽  
Clinical Decision Making ◽  
Conflicts Of Interest ◽  
Tertiary Care ◽  
Positive Test ◽  
Care Hospital ◽  
Test Results ◽  
Initial Test ◽  
Lupus Anticoagulants ◽  
Time Point

Introduction: Lupus anticoagulants (LA) are a heterogeneous group of immunoglobulins that develop spontaneously, with autoimmune disorders or transiently in association with acute infectious or inflammatory conditions. Transient LA are generally presumed to be harmless, while LA that persist over time may be a risk factor for venous and arterial thrombosis. Accordingly, persistence of LA after a first thrombotic episode may signal a recommendation for long term thromboprophylaxis with an anticoagulant, thus, to guide therapy, correct interpretation of LA test results is paramount. LA test interpretation is complicated, however, and clinicians must understand the LA test characteristics, the importance of timing of testing and the implications of positive, negative and equivocal test results to use the information effectively for clinical decision making. We undertook this study to ascertain how clinicians at our institution approach LA testing and to identify knowledge gaps that may amenable to educational interventions aimed at improving patient care in this area. Methods: Our laboratory uses a combination of the dilute Russell viper venom time (dRVVT) and silica clotting time (SCT) for LA screening (Instrumentation Laboratories, Bedford MA, USA). A positive test for either dRVVT or SCT is considered positive for LA. Negative tests for both are required to exclude the presence of LA in a given patient. We provide cutoff values for negative, positive and indeterminate test results and recommend repeat testing after 12 weeks for any indeterminate or positive test to establish persistence in accordance with current guidelines. We recommend NOT testing patients who are currently anticoagulated with a direct oral anticoagulant (DOAC) due to the potential for a false positive test result. We retrospectively analyzed 715 completed LA tests between April 1, 2018 and April 30, 2019 to determine the proportion of positive, negative and indeterminate test results. We then reviewed individual patient records to identify patient and provider characteristics and document additional diagnostic actions taken based on the initial test results. We report our findings descriptively. Results: The average age of patients undergoing laboratory testing for LA was 46.9 years, (median, 47.0 years), with a preponderance of females (73%). The majority of tests were ordered by rheumatology or hematology providers (53%). Anticoagulation with a DOAC was present in 74 (10%). A negative initial test (dRVVT and SCT both negative) was documented in 413 patients (58%), and was repeated in nine individuals (2%) at a second time point. A positive test (dRVVT and/or SCT positive) was documented in 170 (24%), of which 53 (31%) were repeated subsequently and 18 (11%) were themselves repeat tests to follow up on a previous positive test, leaving 99 (58%) initial positive tests that were not repeated. The majority of repeat tests were conducted at a time point <12 weeks after the initial test (n = 37; 70%). Equivocal test results (dRVVT and/or SCT indeterminate) were obtained in 132 patients (18%) and repeated in 25 (19%). Conclusion: We discovered a surprisingly high rate of inappropriate LA test usage at our institution. The results of this investigation will guide our efforts to develop interventions aimed at informing our clinicians about best practices for laboratory testing for LA, and provide opportunities to leverage the features of the electronic health record to improve test ordering procedures. Disclosures No relevant conflicts of interest to declare.

scholarly journals Utilizing the Predictive Value of the 4T Scoring System to Reduce Unnecessary HIT Panel Costs in the Community Hospital Setting

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 5001-5001 ◽  
Author(s):  
Rashmika Potdar ◽  
Sorab Gupta ◽  
Jia Hwei Ng ◽  
Schoepe Robert ◽  
Andrew Berson ◽  
...  
Keyword(s):  
Scoring System ◽  
Community Hospital ◽  
Conflicts Of Interest ◽  
Hospital Setting ◽  
Immunological Response ◽  
Retrospective Chart Review ◽  
Turnaround Time ◽  
Study Objective ◽  
Heparin Administration ◽  
4T Score

Abstract Abstract Study Objective-Heparin Induced Thrombocytopenia (HIT) is a life-threatening immunological response to heparin. The objectives for this study were to determine if the 4T scoring system was being utilized as a tool for predicting HIT, and to look at the costs associated with HIT panels. Methods-This was a retrospective chart review of patients greater than 18 years of age who had HIT panels performed between January 2013 and June 2014 in a community hospital. Any duplicate HIT panels sent during the same admission period were excluded. Study investigators were trained in two 30-minute intervals in the area of data collection and retrospective calculation of 4T score. Results- Of the 154 patients studied, 73 (47.4%) were male, and 81 (52.6%)were female. All patients had a 4T score calculated by study investigators during data analysis, and 1.29% (n=2) had a 4T score calculated before a HIT panel was sent by the team taking care of the patient. 62.3% (n=96) of patients had a low 4T score and 37. 7%( n=58) had an intermediate to high 4T score. Hematology was consulted on 57.7% (n=89) and anticoagulant administration was stopped on 74 % (n=114), while in 26 % ( 40/ 154) heparin was continued despite sending HIT. 25.4%(29/114) were started on alternate anti- coagulants after stopping heparin . Throughout the course of the study, 20 patients died, with only 1 of these patients being HIT positive. If 100 unnecessary HIT panels were performed in a year, the hospital would be charged more than $20,000 by the diagnostic lab. Additional costs include the halting of Heparin administration and starting an alternate anticoagulant such as Argatroban. 24 hour administration of Argatroban costed $1,000 for continuous infusion. HIT panels have a turnaround time of 4-5 days, resulting in the additional charge of $5,000 just for Argatroban administration. A lengthened stay in the hospital due to HIT panel turnaround time is also a source of increased costs. Combined, the ordering of a HIT panel, alternate anticoagulant administration, and bed charges could amount to $40,000 over the course of four days. This time and money could be put to better use treating the underlying disease of the patient, instead of focusing on the testing for HIT. Conclusion-Management of HIT in community hospital was sub-optimal. Lack of utilization of the 4T scoring system led to unnecessary ordering of HIT panels. This increased duration of hospital stay, elevated the cost of treatment, and resulted in the holding of prophylactic anticoagulants. Disclosures No relevant conflicts of interest to declare.

scholarly journals A Restructured Approach to Diagnosis of Heparin Induced Thrombocytopenia in a Large Tertiary Hospital

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3525-3525
Author(s):  
Sriman Swarup ◽  
Somedeb Ball ◽  
Nimesh Adhikari ◽  
Courtney Alice Welch ◽  
Jaden Fackrell ◽  
...  
Keyword(s):  
Screening Test ◽  
Laboratory Testing ◽  
Conflicts Of Interest ◽  
False Negative ◽  
Serotonin Release ◽  
Efficient Manner ◽  
Improvement Project ◽  
Heparin Induced Thrombocytopenia ◽  
Cost Efficacy ◽  
4T Score

Abstract Background The standard practice for diagnosis of heparin-induced thrombocytopenia (HIT) involves a combination of 4T score and laboratory tests, such as enzyme immunoassay for detection of antibodies. We noted a lack of widespread use of 4T score in our practice setting. We also found that our laboratory utilized Particle Immunofiltration Assay (PIFA) for HIT screening, which has been shown to have questionable diagnostic utility in HIT diagnosis (Warkentin et al., 2007). The study aims to improve the rate of 4T score usage in conjunction with an improved laboratory diagnostic test for patients with suspected HIT in a cost-efficient manner. Method We initiated a quality improvement project involving the review of all patients with laboratory orders for PIFA testing between March 2017 to March 2018, explicitly assessing for documented 4T scores before the ordering of PIFA. Three of the investigators also calculated 4T scores for these patients at the time of laboratory testing and noted the results of the serotonin release assay (SRA), if ordered. We further collected data on any alternative anti-coagulation used in such patients for a cost-efficacy analysis later. Results A total of 170 PIFA tests were ordered during the period of investigation. Only five (0.02%) of these patients had a documented 4T score at the time of testing. One hundred thirteen patients (66.4%) had a low 4T score per investigator-calculation. Forty-seven patients (27.6%) were noted to have intermediate 4T scores. Lastly, ten patients (0.05%) were observed to have high 4T scores. A total of 32 SRAs were ordered; five of which were positive (four with an intermediate 4T score and one with high 4T score). PIFA was false-negative in two confirmed cases of positive SRA and false-positive in 13 instances of negative SRA. Thus, in this study, the sensitivity of PIFA was noted to be 60%, and specificity was observed to be 50%. Nineteen patients also received alternative parenteral anti-coagulation (fondaparinux or argatroban); seven of these were with low, eight with intermediate, and four with high 4T scores. Conclusion The study highlights the need for improving 4T score usage rates in our hospital as well as a need for switching to an alternative HIT screening test to promote patient safety and cost efficacy. Hence, we have begun the integration of 4T score with laboratory testing into the electronic medical record, alongside a shift in our HIT screening test from PIFA to the recently FDA-approved automated latex immunoturbidimetric assay. We will be continuing analysis of patients with suspected HIT for another six months to assess the effects of the above interventions. Figure. Figure. Disclosures No relevant conflicts of interest to declare.

Use of Computed Tomography Pulmonary Angiography for Suspected Pulmonary Embolism in Patients with Malignancy- a Single Center Experience

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5907-5907
Author(s):  
Sravanthi Ravulapati ◽  
Cerena K Leung ◽  
Mudresh R Mehta ◽  
Kara M Christopher ◽  
Susan K. Woelich ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Emergency Department ◽  
Pulmonary Embolism ◽  
Conflicts Of Interest ◽  
Tertiary Care ◽  
Pulmonary Angiography ◽  
Screening Tools ◽  
Intermediate Risk ◽  
Computed Tomography Pulmonary Angiography ◽  
Increased Risk

Abstract Background: Pulmonary embolism (PE) is a potentially lethal condition commonly suspected in patients with malignancy. Computed Tomography Pulmonary Angiography (CTPA) is increasingly used in the diagnosis of PE, and guidelines have incorporated various screening tools including the Modified Geneva and Wells criteria to facilitate exclusion of pulmonary embolism. There is an increased risk of venous thromboembolism in patients with active malignancy and therefore an increased suspicion in patients who present to the emergency department (ED) with concerning symptoms. Methods: This is a retrospective analysis at a single tertiary care institution. All patients initially diagnosed with an active malignancy since 2005 and underwent a CTPA between January 2010 and October 2015 were reviewed. Patients were excluded if the CTPA was performed in the setting of trauma, a history of benign malignancy, or if the diagnosis of malignancy was made subsequent to the CTPA. Data collected included patient demographics, clinical presentation, type of malignancy and treatment regimen received. The modified Geneva and Wells criteria were applied to all patients independent from the initial ED risk assessment for a PE. Results: There were 796 patient records reviewed, of which 162 patients met inclusion criteria. Out of these 162 patients, only 8 (4.9%) were found to have a pulmonary embolism. All patients with a positive CTPA had an intermediate risk per the Geneva criteria while only 62.5% had an intermediate risk per the Wells criteria. Of the 154 patients with a negative CTPA, 71.5% and 78.7% had an intermediate risk; 22.5% and 18.7% were classified as low risk based on Wells and Geneva criteria, respectively. The median age of patients was 59 years old, and the majority were male (58%). The most common malignancies in which a CTPA was ordered were lung cancer (27.7%) followed by breast cancer (14.9%) and prostate cancer (6.8%). Despite a negative CTPA, 82 out of 154 patients (53%) were admitted to the hospital. Conclusion: Pulmonary embolism is commonly associated with and frequently suspected in patients with active malignancy. The incidence of PE over a 5-year period in oncology patients was 5% in our emergency department. In total, 18.7% to 22.5% of patients could have avoided a CTPA if scoring was based on the Wells or Geneva criteria. Based on the review at our institution, the modified Geneva and Wells criteria are not adequate, and a new tool needs to be developed for risk stratification for the diagnosis of PE specifically in patients with active malignancy. Disclosures No relevant conflicts of interest to declare.

Evaluation of the Pre-Test Scoring System (4Ts) for the Evaluation and Management of Heparin Induced Thrombocytopenia

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2551-2551
Author(s):  
Rodina Vatanparast ◽  
Prasad Pillai ◽  
Gregory Crane ◽  
Steven Minter ◽  
Kristine Ward ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Scoring System ◽  
High Probability ◽  
Conflicts Of Interest ◽  
Direct Thrombin Inhibitor ◽  
Thrombin Inhibitor ◽  
Heparin Induced Thrombocytopenia ◽  
Low Probability ◽  
Turn Around Time ◽  
4T Score

Abstract Abstract 2551 The initial diagnosis of Heparin Induced Thrombocytopenia (HIT) is made on clinical grounds, because the assays with the highest sensitivity (Heparin-PF4 Ab ELISA) and specificity (Serotonin Release Assay) may not be readily available and may have a slow turn-around time. The clinical utility of the pretest scoring system, the 4Ts, was developed and validated by Lo, GK et al in the Journal of Thrombosis and Haemostasis in 2006. The pretest scoring system looks at the degree of thrombocytopenia, timing of platelet fall, thrombosis or other sequelae, and the possibility of other etiologies for thrombocytopenia. Based on the 4T score, patients can be divided into high, intermediate, and low probability of having HIT. The American Society of Hematology developed a clinical practice guideline in 2009 incorporating the 4T scoring system in the evaluation and management of patients with suspected HIT. It is recommended that patients with intermediate to high probability for HIT start direct thrombin inhibitor (DTI) therapy without delay. We conducted a retrospective study on 100 consecutive patients who were tested for the HIT assay during their hospitalization at Hahnemann University Hospital in 2009. In the 100 patients analyzed, the distribution of the 4T score of low, intermediate, and high pretest probability were seen in 73, 23 and 4 patients, respectively. A positive HIT ELISA (optical density > 1.0) was detected in 0/73 (0%) of the low probability group, 5/23 (22%) of the intermediate probability group and 2/4 (50%) of the high probability group. The average turn-around time for the HIT ELISA was 4 to 5 days. Fourteen (19%) out of the 73 patients with a low pre-test probability for HIT were treated with a direct thrombin inhibitor (DTI). Ten out of the 14 (71%) patients in the low probability group treated with a DTI had a major complication of bleeding requiring blood transfusion support. Overall, twenty five patients received a DTI. Argatroban was the DTI used in 24 of 25 patients. Fourteen patients started on argatroban had a contraindication for the use of lepirudin. In this retrospective study, a low 4T score correlated 100% with a negative HIT antibody assay. The 4T score also predicted the patients likely to test positive for HIT into the intermediate to high probability group. There was significant patient morbidity in the group with low probability when treated with a direct thrombin inhibitor. Based on previous data and this retrospective study, empiric direct thrombin inhibitor therapy should not be initiated in patients with low probability of having HIT. Moreover, many of these patients were started on the more expensive direct thrombin inhibitor, argatroban. For our institution, if no contraindication exists, we recommend lepirudin for the treatment of HIT because it is easier to monitor and less costly. Furthermore, we recommend incorporating the 4T scoring system into institutional core measures when assessing a patient with suspected HIT, selecting only patients with intermediate to high probability for further therapeutic intervention, which may translate into reduced morbidity and lower health care costs. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Effective Implementation of a Structured Protocol for Facilitation of the Judicious Use of Antibody Test for Diagnosis of Heparin Induced Thrombocytopenia

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3462-3462 ◽  
Author(s):  
Somedeb Ball ◽  
Nimesh Adhikari ◽  
Anita Sultan ◽  
Kyaw Zin Thein ◽  
Khatrina Swarup ◽  
...  
Keyword(s):  
Phase I ◽  
Phase Ii ◽  
High Probability ◽  
Conflicts Of Interest ◽  
Successful Implementation ◽  
Efficient Manner ◽  
Platelet Factor ◽  
Heparin Induced Thrombocytopenia ◽  
Low Probability ◽  
4T Score

Introduction: Heparin induced thrombocytopenia (HIT) is a serious prothrombotic condition, usually triggered by exposure to heparin products with formation of antibodies to platelet factor 4/ heparin polyanion complexes. Diagnostic algorithm for HIT combines clinical scoring (4T score) with time sensitive screening for HIT antibodies (HIT-ab), while serotonin release assay (SRA) is remains the gold standard for confirmatory diagnosis. The rate of utilization of 4T score was low in our institution, resulting in inappropriate orders for HIT-Ab test and subsequent administration of unnecessary alternative anticoagulation (AC) in patients with false positive results. In this project, we designed a structured HIT diagnostic workflow incorporating 4T score calculation in our electronic medical record (EMR) and replaced particle immunofiltration assay (PIFA) with latex immunoturbidometric assay (LIA) in our laboratory for HIT-Ab screening, with an aim to improve the rate of 4T utilization and accuracy of HIT diagnosis in a cost-efficient manner. Methods: In phase I, we performed a retrospective chart review of all patients with PIFA ordered between March 2017-March 2018. Two investigators independently calculated 4T, collected data on results of HIT-Ab, confirmatory SRA tests, and the duration of alternative AC from each record. Any variations in 4T score were resolved by a senior investigator. In phase II, we implemented a new workflow in the EMR incorporating mandatory calculation of 4T score with every order for HIT-Ab test. Our lab started using LIA in place of PIFA. Charts were reviewed on patients with HIT-Ab orders (LIA) from January-June of 2019. Results: On review of data from phase I, we noted that 4T score was documented in only 5 (0.02%) of 170 patients in whom a PIFA test was ordered. Per investigators assessment, 113 (66.4%) patients had low probability (4T ≤ 3), 47 (27.6%) had intermediate probability (4T 4 or 5), and 10 (5.8%) had a high probability (4T ≥ 6) for a diagnosis of HIT. SRA was ordered in 32 patients, although 17 of them had low probability per investigator assessment. PIFA test came back positive in 26 patients, of whom 16 had corresponding SRA results, and three samples were positive for SRA. PIFA was negative in two patients with confirmed HIT (SRA positive). A total of 19 patients received alternate AC in the first phase, 7 of them had low 4T score per our assessment. In phase II, 69 records were found with available LIA results, showing a relative decrease in HIT-Ab orders compared to earlier phase at the six months mark. Documentation of 4T score has been 100% by ordering physicians, a certain improvement from phase I. Investigator calculated 4T score showed low probability in 33 (47.8%) patients, intermediate probability in 31 (44.9%) patients, high probability in 5 (0.07%) patients. LIA was positive in 7 of the 69 ordered tests, 6 of whom scored high/intermediate in the 4T score. HIT diagnosis was confirmed in 3 of these 7 patients with a positive SRA result. During this period, all the 7 of the eight patients who received alternate AC had a high or intermediate probability for HIT as per 4T. Conclusion: Our study demonstrated that the successful implementation of a structured protocol for HIT diagnosis ensured 100% adherence to the calculation and documentation of 4T score by clinicians, and significantly reduced the number of inappropriate HIT-Ab test orders in our institution. Use of alternate AC was also more consistent with the level of probability for HIT. Table Disclosures No relevant conflicts of interest to declare.

scholarly journals Utility and Pitfalls of Stepwise Laboratory Testing for Heparin Induced Thrombocytopenia: Retrospective Review from an Academic Medical Center

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2371-2371 ◽  
Author(s):  
Joshua Kra ◽  
Helen Horng
Keyword(s):  
Laboratory Testing ◽  
Laboratory Tests ◽  
Medical Center ◽  
Academic Medical Center ◽  
Clinical Suspicion ◽  
Functional Assay ◽  
Heparin Induced Thrombocytopenia ◽  
Academic Medical ◽  
Elisa Testing ◽  
4T Score

Introduction: Heparin induced thrombocytopenia (HIT) occurs in up to 5% of adults exposed to heparin due to formation of heparin-dependent antibodies to the heparin/platelet factor 4 (PF4) complex. Patients develop thrombocytopenia and are at risk for severe thrombotic complications. Mortality rates can be as high as 20%, but are often much lower with prompt recognition, cessation of heparin, and treatment with alternative anticoagulants. However, these alternative medications are often both labor-intensive drips and expensive, highlighting the need for quick decision making in such challenging cases. The classic workup of HIT involves assessing clinical suspicion (often using the "4T score" on a scale of 0-8), followed by lab testing for detection of the heparin-dependent antibody and then a functional assay to confirm pathogenicity of the antibody. Our institution uses an in-house rapid Particle ImmunoFiltration Assay (PIFA), which is a same-day test and reported as "positive" or "negative." Other testing available includes send-out tests for Enzyme-Linked Immunoassay (ELISA) to IgG, A, and M of the PF4 antibody as well as the C-14 Serotonin Release Assay (SRA) functional assay. The goal of this retrospective review is to analyze the utility of an algorithmic approach to laboratory testing in aiding the rapidity of diagnosis of HIT without missing possible critical cases. Methods: This was a single institutional study at a large urban academic medical center. We reviewed inpatient charts from 2015-2018 of patients who had any lab testing for HIT. As per institutional guidelines, first-line testing is recommended by using the in-house same-day testing PIFA. If positive, a sample is automatically reflexed and sent-out for PF4 ELISA testing and SRA. Furthermore, clinicians are able to directly order ELISA and SRA testing at their medical discretion. Our analysis looked at those patients with at least two different "HIT-related" laboratory tests to best analyze the concordance and discordance rates of the above testing to assess for sensitivity, specificity, and overall accuracy of using a stepwise testing approach. We used a cutoff value of >0.4 optical density (OD) for ELISA testing, and >20% release at low-dose heparin concentration for SRA testing. Results: There were 118 patients who had at least two different HIT-related laboratory tests sent. 91 patients had both PIFA and ELISA testing, with 37/79 (47%) positive concordance rate and 6/12 (50%) negative concordance rate, for a sensitivity of 86% and specificity of 13%. 3 patients with positive PIFA also had positive SRA, and there were 2 patients with negative PIFA with positive SRA testing (see attached Table). When comparing ELISA testing to SRA, 4/41 (10%) had concordant positive testing, while no patient with a negative ELISA test had a positive SRA (28 concordant negative cases). Overall, of 94 SRA tests run, 5 were positive, of which 2/5 had negative PIFA and 0/4 had negative ELISA testing. Conclusions: While PIFA testing had a high sensitivity compared to ELISA, the overall accuracy compared to ELISA was low, while ELISA testing was 100% sensitive in this analysis. Furthermore, there was still a risk of missing cases of HIT using PIFA testing alone. In both cases of positive SRA with a negative PIFA, patients had a high 4T score of >6, consistent with a high clinical suspicion for HIT. We conclude that PIFA testing is not equivalent to ELISA testing, and that use of a laboratory "algorithm only" approach would be inappropriate in the diagnosis of HIT. Our results highlight the importance of using both clinical scoring systems and appropriate lab testing together in the workup and diagnosis of HIT. Disclosures No relevant conflicts of interest to declare.

scholarly journals A Single Institution's Adherence to Heparin-Induced Thrombocytopenia and Thrombosis Testing Guidelines

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 4720-4720
Author(s):  
Kristine Gade ◽  
Jack Melson ◽  
Alex Jepsen ◽  
Surabhi Palkimas ◽  
Bethany Horton ◽  
...  
Keyword(s):  
Laboratory Testing ◽  
Choosing Wisely ◽  
Antibody Assay ◽  
Heparin Induced Thrombocytopenia ◽  
Probability Score ◽  
Low Probability ◽  
To Receive ◽  
Test Probability ◽  
4T Score ◽  
Platelet Antibody

Abstract Introduction: What was once an under-recognized clinical entity, heparin induced thrombocytopenia and thrombosis (HITT) has become a well-recognized and frequently tested disease. HITT is a serious and potentially fatal antibody mediated drug reaction to platelet factor 4 and early identification and treatment is essential. The 4T score is well-validated to guide appropriate testing of HITT where a low-probability score of 0-3 equates to a 99.8% negative predictive value for HITT2,3. In an effort to promote cost-conscious care and efficient use of healthcare resources, the American Society of Hematology (ASH) recommends against testing for HITT if the 4T score is 3 or less4. HITT laboratory testing at our institution is not restricted based on 4T score. We hypothesize that many providers are not following cost-conscious guidelines regarding HITT testing at our institution. Methods: We performed a single-institution retrospective analysis of patients who had a heparin-induced platelet antibody assay with reflexive serotonin release assay ordered between July 1, 2016 to July 1, 2017 at the University of Virginia Medical Center (UVA). We primarily assessed how our institution's ordering of heparin-induced platelet antibody for HITT compared to ASH's Choosing Wisely recommendation of forgoing laboratory testing on patients with a 4T score of 0-3 by retrospectively calculating 4T scores on all patients who had laboratory testing4. Patients were also assessed for episodes of bleeding and clotting and were scored on severity via the CTCAE and ISTH grading systems. Data on anticoagulant used after HITT testing was collected. We also checked to see if the blood specimen for assay was collected 2 hours after last heparin product as recommended by lab. Patients were excluded if they were not inpatient when their heparin-induced platelet antibody assay was drawn or if they were transferred or discharged immediately after assay was collected. Ultimately, of the initial 196 patients who had heparin-induced platelet antibody assay collected during this time frame, 184 patients were included for analysis. Results: Of the 184 patients who had a heparin-induced platelet antibody assay sent and were included in analysis, 55.4% of the patients (n=102) had a low pre-test probability of HITT with a 4T score of less than or equal to 3. Of the patients who had HITT testing sent, only 44% (n=81) received treatment with a non-heparin anticoagulant. Of the 102 patients who had a low pre-test probability of HITT with a 4T score of ≤3, 37.3% (n=38) were placed on an alternative anticoagulant. Of this low pre-test probability of HITT cohort, 7.8% (n=8) experienced bleeding as a complication. Interestingly, 15.5% (n=29) of all patients who had HITT testing continued to receive heparin products while awaiting results. Additionally, 19.3% (n=36) of samples were drawn within 2 hours of receiving heparin products. Conclusion: The guidelines for HITT testing and treatment have been well-validated and widely disseminated. Despite providers' familiarity with this clinical entity, the results depict that ordering practices at our institution do not follow guidelines in cost-conscious ordering nor in standard of treatment. Applying ASH's Choosing Wisely recommendation of not ordering laboratory testing on patients with a 4T low-probability score of 0-3, we see that 55.6% of the HITT assays ordered in this time period were inappropriate and at a cost of $455 to the institution per assay resulted in $46,865 of unnecessary health care costs to our institution in one year's time. This does not include the cost of alternative anticoagulation. Heparin costs just $0.04 per mL while argatroban costs $3.81 per mL and bivalirudin $12 per mL resulting in a 100 to 300 fold cost increase respectively. Standard work regarding HITT assay collection and treatment does not exist at our institution. Of concern, 15.5% of patients continued to receive heparin products after HITT testing was sent. The results of this study prompted implementation of a quality improvement project to decrease inappropriate HITT testing and standardize treatment of suspected HITT via an electronic medical record order set that uses the 4T score to suggest appropriate ordering of assays. We plan to collect data on changes in our ordering practices after this intervention. Disclosures No relevant conflicts of interest to declare.

Sign in / Sign up

Export Citation Format

Share Document