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 Predictive value of the 4Ts scoring system for heparin-induced thrombocytopenia: a systematic review and meta-analysis

Blood ◽  
2012 ◽  
Vol 120 (20) ◽  
pp. 4160-4167 ◽  
Author(s):  
Adam Cuker ◽  
Phyllis A. Gimotty ◽  
Mark A. Crowther ◽  
Theodore E. Warkentin
Keyword(s):  
Systematic Review ◽  
Predictive Value ◽  
Scoring System ◽  
High Probability ◽  
Meta Analysis ◽  
Eligibility Criteria ◽  
Heparin Induced Thrombocytopenia ◽  
Cochrane Database ◽  
Clinical Scoring ◽  
Low Probability

Abstract The 4Ts is a pretest clinical scoring system for heparin-induced thrombocytopenia (HIT). Although widely used in clinical practice, its predictive value for HIT in diverse settings and patient populations is unknown. We performed a systematic review and meta-analysis to estimate the predictive value of the 4Ts in patients with suspected HIT. We searched PubMed, Cochrane Database, and ISI Web of Science for studies that included patients with suspected HIT, who were evaluated by both the 4Ts and a reference standard against which the 4Ts could be compared. Quality of eligible studies was assessed by QUADAS-2 criteria. Thirteen studies, collectively involving 3068 patients, fulfilled eligibility criteria. A total of 1712 (55.8%) patients were classified by 4Ts score as having a low probability of HIT. The negative predictive value of a low probability 4Ts score was 0.998 (95% CI, 0.970-1.000) and remained high irrespective of the party responsible for scoring, the prevalence of HIT, or the composition of the study population. The positive predictive value of an intermediate and high probability 4Ts score was 0.14 (0.09-0.22) and 0.64 (0.40-0.82), respectively. A low probability 4Ts score appears to be a robust means of excluding HIT. Patients with intermediate and high probability scores require further evaluation.

scholarly journals The Appropriateness of Heparin Antibody Testing. A Single Institution Retrospective Analysis

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3277-3277 ◽  
Author(s):  
Danny A. Landau ◽  
Nadezhda Kholodnaya ◽  
Ana CuestaFernandez ◽  
Ariel PerezPerez
Keyword(s):  
Internal Medicine ◽  
Hospital Stay ◽  
Scoring System ◽  
High Probability ◽  
Conflicts Of Interest ◽  
Length Of Hospital Stay ◽  
Low Risk ◽  
Antibody Testing ◽  
Drug Induced ◽  
Heparin Induced Thrombocytopenia

Abstract Background: Heparin-induced thrombocytopenia (HIT) is a drug-induced, immune-mediated prothrombotic disorder associated with thrombocytopenia and venous and/or arterial thrombosis.Up to 5% of patients exposed to heparin for at least one week develop HIT, and approximately 50% of them will have thrombosis. Diagnosis of HIT is suspected from the clinical picture based on the ''4 T's'' (Thrombocytopenia, Timing, Thrombosis, no other cause of platelet fall) or the HIT Expert Probability (HEP) scoring system. However, often these "4 T's" are ignored and testing is inappropriately ordered in low risk patients. This could lead to possible morbidity and increase length of hospital stay. We opted to look back at the appropriateness of testing done within our academic center. Methods/ Design: All hospitalized patients with thrombocytopenia who underwent HIT antibody testing (HIT ELISA) during February 2013 were screened using our internal electronic medical record. Patients were subdivided to low, intermediate or high pretest probability group according to the 4Ts scoring system. Appropriateness of testing was determined according ASH 2013 Clinical Practice Guideline on the Evaluation and Management of Adults with Suspected Heparin-Induced Thrombocytopenia (HIT). HIT Ab test is recommended to be tested when there is intermittent to high probability of HIT (4T's score above or equal to 4). The percentage of appropriate/inappropriate testing was calculated. The results were then subdivided by ordering physician group. Results: 120 HIT ab tests were performed during February 2013 in our institution. Only 13 patients tested had a positive HIT Ab. Internal medicine ordered the majority of these tests. Of the 120 patients tested, 7 patients had high risk and another 50 had intermediate risk as per 4T's scoring. 61 patients were low risk and should not have been tested. (Table 1) Table 1. HIT antibody test ordered per Service and probability of HIT. Service ordering test Low probability of HIT Intermediate/high probability of HIT TOTAL Internal Medicine 28 28 56 Cardiothoracic Surgery 13 11 24 Hematology Oncology 7 5 12 Cardiology 3 1 4 Surgery 1 4 5 Emergency medicine 0 1 1 Infectious disease 4 0 4 Pulmonary 0 1 1 Critical care 1 6 7 Nephrology 1 2 3 Ob Gyn 1 0 1 Family Medicine 2 0 2 TOTAL 61 59 120 Conclusions: HIT testing has been overused within our institution. Low platelets, without other signs or symptoms of typical HIT were used as a trigger for testing the antibody. This has potential to cause harm due to increased bleeding risk, increased length of hospital stay, and the potential to utilize extended anticoagulation when not necessary. Better education on the appropriateness of the test can limit the potential harm of its use. Disclosures No relevant conflicts of interest to declare.

Initial Management of Suspected Heparin-Induced Thrombocytopenia: Opportunities for Education

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4686-4686 ◽  
Author(s):  
Melody Smith ◽  
Jonathan E Dowell ◽  
Eugene P. Frenkel ◽  
Ravindra Sarode ◽  
Yu-Min P Shen
Keyword(s):  
Conflicts Of Interest ◽  
Further Education ◽  
Thrombin Inhibitor ◽  
Sample Population ◽  
Clinical Tool ◽  
Heparin Induced Thrombocytopenia ◽  
Clinical Probability ◽  
Immunologic Assay ◽  
Current Guidelines ◽  
4T Score

Abstract Abstract 4686 According to the current recommendations for patients being evaluated for heparin-induced thrombocytopenia (HIT), a pretest assessment for the probability of HIT should be performed to evaluate the need for laboratory testing and the treatment modality that the patient should receive. The 4T score is an accepted clinical tool used for this purpose. For patients with a 4T score <4 discontinuation of heparin products is not indicated. However, in those patients who have a 4T ≥4, heparin should be discontinued and treatment with a direct thrombin inhibitor (DTI) should be initiated while performing the immunologic assay for HIT antibody. In this study, a database of patients being tested for HIT at our institution was compiled and retrospective analysis was performed to determine whether our treatment population was being managed appropriately. The treatment of 159 patients in whom HIT antibody had been sent over a 2- year period, from 5/2008 to 5/2010, was assessed. Of the sample population, 32/159 (20%) had not been exposed to heparin prior to the HIT antibody being sent. Furthermore, the majority of the patients, 104/159 (65%) had a 4T score <4. Thus fully 85% of the patients tested in this cohort did not need to be tested. Of the latter group with heparin exposure but low clinical probability for HIT, 57/104 (54%) had heparin unnecessarily discontinued once HIT was suspected. Most notably, 23/159 (14%) of the patients had a 4T greater than 4. The data for these patients indicates that the majority of them were not treated as per the current guidelines. As noted in the Table, 69% of these patients had either no treatment, meaning that heparin was not discontinued, or simply had heparin stopped with no DTI initiated. Only 5/23 (22%) of the patients in this cohort were placed on a DTI. Of these patients, 2 were also placed on warfarin, as they were noted to have active thromboses. This data suggests that the management of patients suspected of having HIT at our institution is not consistent with the current recommendations with wasteful practices and inappropriate therapy. These results highlight opportunities for further education of clinicians regarding HIT.No treatmentHeparin stopped onlyDTIWarfarinNot exposed to heparin (n=32)324T less than 4 (n=104)4757004T greater than 4 (n=23)41452 Disclosures: No relevant conflicts of interest to declare.

scholarly journals Confirmation of the Utility of the 4T Scoring System for HIT

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 5816-5816
Author(s):  
Zachary Trisel ◽  
Mark Maddox ◽  
Ahmed Safa ◽  
Thomas Bemis ◽  
Kristine Ward ◽  
...  
Keyword(s):  
Predictive Value ◽  
Scoring System ◽  
High Probability ◽  
Time Course ◽  
Conflicts Of Interest ◽  
University Hospital ◽  
Laboratory Studies ◽  
Low Probability ◽  
The Cost ◽  
Very High

Abstract Background: Heparin-induced thrombocytopenia (HIT) is a complication of heparin-based anticoagulation (AC) resulting in thrombocytopenia and thrombosis. Laboratory testing can often be avoided as the 4T score (4TS) has a negative predictive value (NPV) of 0.998 for low risk patients. Despite this scoring system, which has been validated since 2006, physicians continue to send inappropriate studies despite a low probability of HIT. We sought to evaluate our academic institution's compliance, perform a cost analysis and determine if appropriate AC was initiated. By analyzing our data, we sought to educate our staff and implement measures to improve cost efficiency and quality of care. Methods: We performed a retrospective chart review of patients admitted to Hahnemann University Hospital (HUH) between November 1, 2016 and April 30, 2017 who had HIT antibodies (HITAb) and serotonin release assay (SRA) studies. These laboratory tests were performed at Quest Diagnostics. This data was compiled from the EMR at HUH. According to the 4TS, patients were assigned a score of 0-8: 0-3 for low, 4-5 for intermediate, 6-8 for high probability respectively. Laboratory results of HITAb and SRA were then compared to the calculated 4TS. We then investigated whether appropriate AC was initiated. Data on the cost associated with the inappropriate management of suspected HIT was compiled. Results: 72 patients had HITAb sent during the interval studied. Table 1 shows the 4TS and results of HITAb and SRA testing. Table 2 lists the AC used based on the 4TS. The NPV of not having HIT in the low probability group was 100%. The positive predictive value (PPV) of having HIT in the high probability group was 100%. At our institution, HITAb with reflex SRA costs $503. Expenditure due to inappropriate testing was estimated to be around $23,000 dollars over the study's time course. Inappropriately switching to argatroban cost up to $1,000 per day or fondaparinux $500 per day of overspending on anticoagulation per patient. Discussion: We found the majority of HITAb and SRA testing was unnecessary based on the 4TS. Our data showed a low 4TS had a very high NPV confirming the scoring system's utility. HIT testing was often overutilized as part of a general workup for thrombocytopenic patients who were often septic, on marrow suppressive medications and had multiple comorbidities such as hepatitis and HIV infections which confounded their clinical picture. Furthermore, this scoring system had a very high PPV in the high probability group. This study confirmed that HIT laboratory studies rarely change patient management in these scenarios. With the turnaround time of laboratory studies taking up to 4 days, there is a significant increase to the cost of patient care when solely relying on HITAb and SRA due to the use of expensive anticoagulants. In contrast, it remains unknown if HITAb and SRA could be useful in patients with an intermediate 4TS as our data is limited with no SRA results for patients with intermediate scores and a positive HITAb. To prevent unnecessary testing in the future and to improve the management of HIT, we propose to implement the following at our institution: 1. create a hard stop in our EMR which would prevent studies from being sent off inappropriately; 2. add a 4TS to the calculator section of the EMR and encourage collaboration with the hematology department if additional questions remain after calculating a 4TS; 4. start resident based educational sessions on the importance of calculating a 4TS and its significance prior to sending laboratory studies. In conclusion, the 4TS remains a useful tool to prevent unnecessary diagnostic testing and use of expensive therapeutic anticoagulants in patients with suspected HIT. Disclosures No relevant conflicts of interest to declare.

Safety and Efficacy of Argatroban in the Management of Heparin-Induced Thrombocytopenia

2011 ◽  
Vol 4 ◽  
pp. CMBD.S5118 ◽  
Author(s):  
Bernd Saugel ◽  
Roland M. Schmid ◽  
Wolfgang Huber
Keyword(s):  
Arterial Thrombosis ◽  
Pharmacokinetic Profile ◽  
The United States ◽  
Heparin Therapy ◽  
Direct Thrombin Inhibitor ◽  
Thrombin Inhibitor ◽  
Heparin Induced Thrombocytopenia ◽  
Safety And Efficacy ◽  
Increased Risk ◽  
Life Threatening

Heparin-induced thrombocytopenia (HIT) is a life-threatening adverse reaction to heparin therapy that is characterized by thrombocytopenia and an increased risk of venous and arterial thrombosis. According to guidelines, in patients with strongly suspected or confirmed HIT all sources of heparin have to be discontinued and an alternative, nonheparin anticoagulant for HIT treatment must immediately be started. For both the prophylaxis of thrombembolic events in HIT and the treatment of HIT with thrombosis the direct thrombin inhibitor argatroban is approved in the United States. The objective of this review is to describe the mechanism of action and the pharmacokinetic profile of argatroban, to characterize argatroban regarding its safety and therapeutic efficacy and to discuss its place in therapy in HIT.

Argatroban and Renal Replacement Therapy in Patients with Heparin-Induced Thrombocytopenia

2005 ◽  
Vol 39 (2) ◽  
pp. 231-236 ◽  
Author(s):  
Ignatius Y Tang ◽  
Donna S Cox ◽  
Kruti Patel ◽  
Bharathi V Reddy ◽  
Linda Nahlik ◽  
...  
Keyword(s):  
At Risk ◽  
Renal Replacement Therapy ◽  
Replacement Therapy ◽  
Direct Thrombin Inhibitor ◽  
Thrombin Inhibitor ◽  
Systemic Clearance ◽  
Recovery Method ◽  
P Values ◽  
Heparin Induced Thrombocytopenia ◽  
Alternative Anticoagulation

BACKGROUND: Argatroban, a direct thrombin inhibitor, is an effective anticoagulant for patients who have heparin-induced thrombocytopenia (HIT). Anticoagulation is usually required for renal replacement therapy (RRT). OBJECTIVE: To prospectively evaluate the pharmacokinetics, pharmacodynamics, and safety of argatroban during RRT in hospitalized patients with or at risk for HIT. METHODS: Five patients with known or suspected HIT underwent hemodialysis (n = 4) or continuous venovenous hemofiltration (CVVH, n = 1), while receiving a continuous infusion of argatroban 0.5–2 μg/kg/min. Activated partial thromboplastin times (aPTTs), activated clotting times (ACTs), argatroban concentrations (plasma, dialysate, CVVH effluent), and safety were assessed before, during, and after a 4-hour session of RRT. Systemic and dialytic argatroban clearances were calculated. RESULTS: Among the 4 hemodialysis patients, aPTT, ACT, and plasma argatroban concentrations remained stable during RRT, with respective mean ± SD values of 74.3 ± 34.2 seconds, 198 ± 23 seconds, and 499 ± 353 ng/mL before RRT, and 70.6 ± 21.4 seconds, 181 ± 12 seconds, and 453 ± 295 ng/mL 2 hours after starting RRT (p values NS). Systemic clearance was 17.7 ± 12.8 L/h before hemodialysis and 17.0 ± 9.5 L/h during hemodialysis (n = 2). The dialyzer clearance (dialysate recovery method) was 1.5 ± 0.4 L/h (n = 4). Generally similar responses occurred in the CVVH patient: systemic argatroban clearance was 4.8 L/h before CVVH and 4 L/h during CVVH. The hemofilter argatroban clearance was 0.9 L/h. No bleeding or thrombosis occurred. CONCLUSIONS: Argatroban provides effective alternative anticoagulation in patients with or at risk for HIT during RRT. Argatroban clearance by high-flux membranes during hemodialysis and CVVH is clinically insignificant, necessitating no dose adjustment.

scholarly journals Venous limb gangrene during overlapping therapy with warfarin and a direct thrombin inhibitor for immune heparin-induced thrombocytopenia

2002 ◽  
Vol 71 (1) ◽  
pp. 50-52 ◽  
Author(s):  
Maureen A. Smythe ◽  
Theodore E. Warkentin ◽  
Jennifer L. Stephens ◽  
Dana Zakalik ◽  
Joan C. Mattson
Keyword(s):  
Direct Thrombin Inhibitor ◽  
Thrombin Inhibitor ◽  
Heparin Induced Thrombocytopenia

Incidence of Heparin Induced Thrombocytopenia in the Transplant Population: A Large Retrospective Cohort, Single Transplant Centre Experience

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3320-3320
Author(s):  
Syed Hassan ◽  
Dania Khoulani ◽  
Ami Badami ◽  
Zaid Alirhayim ◽  
Mohamad A. Younes ◽  
...  
Keyword(s):  
Retrospective Cohort ◽  
Conflicts Of Interest ◽  
Organ Transplant ◽  
Serotonin Release ◽  
Confirmatory Test ◽  
Thrombin Inhibitor ◽  
Thromboembolic Events ◽  
Transplant Recipients ◽  
Heparin Induced Thrombocytopenia ◽  
Transplant Patients

Abstract Abstract 3320 Objective: Heparin induced thrombocytopenia (HIT), a prothrombotic complication of heparin therapy, can lead to serious thromboembolic events and cause significant morbidity and mortality. Its occurrence has never been studies in transplant patients, where use of heparin products is very common. We aim to study its prevalence in the transplant population at our institute. Methods: This is a retrospective cohort, single center study which looked into the clinical and laboratory database of all the patients that has undergone any kind of transplant at our institution over a period of 25 years (January 1985 - December 2010). In patients with clinical suspicious of HIT, a pre-test probability was calculated using the 4T scoring system. Results of the laboratory test like the ELISA HIT antibody (HIT ab) test and the functional serotonin release assay test (SRA) along with clinical manifestation of skin necrosis or thromboembolic events were reviewed. Results: Medical records of 2800 patients that has undergone transplant from January 1985- December 2010 were reviewed. HIT antibody assay was performed in 262 patients in which HIT was suspected. Of these, only 48 (18%) patients (mean age 57 ± 11 years, 71% women) had HIT ab positive, 9 were pre transplant recipient and remaining 39 were post transplant recipients. Baseline characteristics of the transplant population are illustrated in Table.1. Confirmatory test, SRA was performed in 8 HIT antibody positive patients, of whom only 4 were positive. The mean 4T score in HIT suspected patients was 3.7 ±1.3, while the score in HIT ab positive patients was 4.2 ± 1.2. Thrombotic complications were seen in 11(0.4%) patients, with the highest incidence rate of 1% in heart transplant recipients. No transplant patient had skin manifestations. Direct Thrombin inhibitor (DTI) was used only in 5 patients who had thrombotic events. No other complication or mortality was reported in any of the HIT ab positive transplant patients. Conclusion: To our knowledge, this is the first study of its kind that has shown very low incidence of HIT in transplant population. In conclusion, transplant patients can safely undergo any type of organ transplant, without having any peri or post operative complications or immediate mortality related to HIT. Disclosures: No relevant conflicts of interest to declare.

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