Are We Doing Too Many HIT Tests? II

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2310-2310
Author(s):  
Ramez Heshmat Awad ◽  
Seshan Subramanian ◽  
Carlos f. Garcia
Keyword(s):  
False Positive ◽  
Arterial Thrombosis ◽  
High Probability ◽  
Elisa Test ◽  
Confirmatory Test ◽  
Severe Thrombocytopenia ◽  
Observation Unit ◽  
Probability Score ◽  
Low Probability ◽  
4T Score

Abstract Back Ground: Heparin Induced Thrombocytopenia is a complex immune disorder related to exposure to heparin that results in arterial and venous thrombosis and moderate to severe thrombocytopenia. Incidence is 0.8-1% in hospitalized patients exposed to heparin. However there is a problem with over testing for HIT syndrome that it is not only financially burdensome but that treating false positive patients with anticoagulation can increase their risk for bleeding. Objective: To determine the actual incidence of Type II-HIT compared to the frequency and necessity of testing in a single urban, teaching, community hospital in Chicago. Methods: A retrospective review of lab records for patients who were tested for HIT syndrome by H-PF4 -ELISA through 2 years Jan 2013-Dec 2014. Then each patient's chart was reviewed. Patients were categorized according to requesting department (i.e. ICU, ED, Medical and surgical floors) then screened for date of admission, date of onset of platelet drop, degree of platelet drop, incidence of DVT, PE, arterial thrombosis and bleeding and finally for possible reasons of platelet count drop other than HIT for calculation of Pretest probability by the 4T score. According to the 4T criteria patients were categorized as low (score 0-3), intermediate (score 4, 5) and high probability (score 6-8). All charts with positive ELISA were reviewed for SRA (Serotonin Release Assay) results. Also contacted lab and pharmacy for cost of HIT testing, confirmatory test with SRA and the cost of Argatroban to be able to determine the economic burden of over testing for HIT syndrome. Results: an average of about 20,000 admissions per year. Over the year 2013, 110 patients were screened for HIT. Over the year 2014, 87 patients were tested for HIT. Of total of 197 tests ordered over the 2 years period 19 Patients did not have enough data in the charts for determination of 4T score and were so excluded. Of the remaining 178, 85(45%) were sent from ICU, 61(32.6%) from Medical floors, 28(15%) from CCU, 9(4.8%) from Surgical floors, 1(0.5%) from Rehab unit, 1(0.5%) from ED and 1(0.5%) from Observation Unit. 17(9.5%) Patients had proven DVT, PE or arterial thrombosis. 2(1%) Patients had evidence of bleeding. According to 4T score139 (74.3%) of 178 were low, 34(18%) intermediate and 5(2.6%) were high probability. ELISA test was positive for only 34(19%) patients of the 178 of which only 3(1.6%) were proven true positive by SRA, 12(6%) had no SRA result in their chart and 19(10.6%) had negative SRA results. ELISA was positive in 22 cases with Low Probability score, 9 Intermediate probability and 3 high probability. Of the 22 low probability ELISA positive cases only 1 (4%) was SRA positive, 15(68%) were SRA negative and 6(27%) did not have SRA in the chart. ELISA test costs 233$, SRA test costs 50$ and one day of Argatroban costs average of 663.44$.Thus the calculated cost of testing for low probability patients reached 32,387 $ for ELISA and 800$ for SRA. Cost of treating false positive patients with Argatroban for an average of 3 days until SRA results are available is 43,758$. Conclusion: From this study we concluded that in our facility we continue to do too many HIT studies without appropriate prescreening with added cost of testing and treatment for low probability patients of almost 77,000$ over the period of two years. In planning to avoid unnecessary testing and treatment for false positive patients we plan to build a 4T score calculator into our Electronic Medical Record System that is started once a HIT test is ordered to improve the screening process. We will also continue work with the Internal Medicine residency program and medical staff to improve teaching on HIT syndrome and other conditions with similar presentations. Table 1. Number of Tests per Department Department Number of tests sent ICU 86(45%) CCU 28(15%) Medical Floors 61(32.6%) Surgical Floors 9(4.8%) Rehab Unit 1(0.5%) ED 1(0.5%) Observation Unit 1(0.5%) Total 187 Table 2. Tests Categorized into Low, Intermediate and High Probability according to 4T score Low Probability Intermediate Probability High Probability 139(74.3%) 34(18%) 5(2.6%) Table 3. SRA Results for ELISA positive patients per Each Probability Category Low Probability Intermediate Probability High Probability 22(64.7%) 9(26.4%) 3(8%) SRA Positive SRA Negative SRA Unavailable SRA Positive SRA Negative SRA Unavailable SRA Positive SRA Negative SRA Unavailable 1(4%) 15(68%) 6(27%) 2(22%) 4(44%) 3(33%) 0 1(33%) 2(66.6%) Disclosures No relevant conflicts of interest to declare.

scholarly journals Are We Doing Too Many HIT Tests III?

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2444-2444
Author(s):  
Syed Zia-ur-Rehman Shah ◽  
Seshan Subramanian
Keyword(s):  
Health Care ◽  
False Positive ◽  
High Probability ◽  
Elisa Test ◽  
Pretest Probability ◽  
True Positive ◽  
Risk Of Bleeding ◽  
Low Probability ◽  
4T Score ◽  
Order Set

Abstract Background In USA in 2007, it was estimated that approximately one third of hospitalized patients, approximately 12 million patients per year receive heparin. Heparin induced thrombocytopenia (HIT) is one of the serious complications of Heparin resulting from immune mediated antibody. 4Ts score is the imperative tool to help differentiate HIT from other causes of thrombocytopenia. The 4Ts score decreases not only risk of bleeding by avoiding anticoagulant but also cost of health care by testing only patients with intermediate to high pretest probability. Our study suggests 4Ts scores calculators are to be introduced as a part of order set for HIT tests. Objective This retrospective study is Part III of our prior studies " Are We Doing Too Many HIT tests", to decrease false positive HIT patients by improving use and awareness about high negative predictive value of 4T score among physicians. This study was carried out to determine outcomes of our previous study of this series in order to assess the reduction of unnecessary ELISA test orders to diagnose HIT in a single urban community hospital in Chicago. 　 Method A retrospective chart review of medical records of the patients (n=181) who underwent H-PF4-ELISA for HIT screening from January 1st, 2016 to December 31st 2017 was conducted. Data was collected from patient's charts which included the requesting department (i.e. ICU, ED, Medical and surgical floors). Also, date of admission, date of onset of platelet drop, degree of thrombocytopenia, incidence of DVT, PE, arterial thrombosis and bleeding and alternative reasons of platelet count drop other than HIT were collected. For each patient a for calculation of Pretest probability by the 4T score was conducted. We stratified these patients based on 4Ts score (0-3) for low probability, (4-5) intermediate probability and (6-8) high probability risk for HIT. We reviewed all charts for which both ELISA and SRA were ordered. Pharmacy department and Hematology labs were contacted to calculate costs of ELISA, SRA and anticoagulation. Results Our results showed that 114 (62.98%) of 181 ELISA tests ordered had low pretest probability for HIT. None of these records were found to be true positive by SRA. However, 24(20%) of low probability category were found positive by ELISA and received anticoagulation and thus were exposed to higher risk of bleeding and additional health care costs. There were 57 (31.49%) out of 181 records had intermediate probability. 16 patients with intermediate probability were ELISA test positive. However, 3 (5.26%) of intermediate probability patients were found to be true positive by SRA. While only 6 (3.31%) out of 181 patients records had high probability for HIT and 3 patients (50%) of high probability were found to be true positive by SRA. However, 11 patients from low probability category and 5 patients from intermediate probability category did not have SRA results in their medical record. Discussion In our previous study, 74.3% of patients tested for HIT during Jan.2013 to Dec. 2014were found to have low probability compared to 62.98% of our current study. Interestingly, patients with intermediate probability have increased to 31.49% from 18% from our previous study. This is a desired decreased. Cost for ELISA test for HIT ranges $200 to $300 per test and cost of SRA is roughly $50 to $60. Cost of one day of Argatroban treatment is roughly $670 which brings the total cost per patient roughly $1000 per day for all those patients who are tested positive by ELISA. 34,200 USD were spent on ELISA test for 114 patients with low probability 4T score who were found true negative. Furthermore, 20 patients with false positive ELISA from low probability 4T category were exposed to 40,200 USD worth of Argatroban during three days while SRA results were awaited. As per our study, educational interventions in our hospital have made remarkable improvement in decreasing the number of ELISA test in patients with low pretest probability from 74.3% to 62.98% Lastly, more than 74,000 USD per 114 patients (with low probability score) could be reduced by introducing "4T score calculation Alert" as a part of order set for HIT in EMR software. We conclude that incorporating prescreening for HIT with 4T score calculation as a part of order set for ELISA could decrease not only the risk of bleeding but also avoidable additional health care cost. Disclosures No relevant conflicts of interest to declare.

scholarly journals Appropriateness of Heparin-Induced Thrombocytopenia (HIT) Testing and the Reliability of 4-Ts Scoring in Critically Ill Patients

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 4988-4988
Author(s):  
Phyo Thazin Myint ◽  
Amani Erra ◽  
Taha Alrifai ◽  
Salman Syed ◽  
Bibek Singh Pannu ◽  
...  
Keyword(s):  
Length Of Stay ◽  
Critically Ill ◽  
Critically Ill Patients ◽  
False Positive ◽  
High Probability ◽  
Icu Patients ◽  
Heparin Induced Thrombocytopenia ◽  
Common Cause ◽  
Icu Length Of Stay ◽  
Low Probability

Abstract Introduction: Thrombocytopenia is a common occurrence in critically ill patients and results in an array of diagnostic workup. Heparin induced thrombocytopenia (HIT) is one of the most frequently ordered tests in this scenario, although it is a less common cause (0.02-0.5%) The over testing and treatment of HIT in Intensive Care Unit (ICU) can lead to a change in medications, and result in side effects, increased ICU length of stay and increased costs. Current guidelines recommend 4-Ts criteria to evaluate the clinical HIT probability in general population, but it may also be used in Intensive Care Unit (ICU) patients. Here, we want to analyze the the usage of 4Ts score in a community hospital and to understand its correlation with HIT testing to see if HIT testing could have been avoided. Methods: We performed a retrospective chart review of adult patients who underwent testing for Heparin Induced Thrombocytopenia anti-platelet factor 4 antibody (anti- PF4 Ab) in ICU at our institution from 03/01/2012 to 02/01/2018. The primary outcomes were set to identify (1) the extent of inappropriate of HIT testing and its consequences in patients with low 4Ts scores, and (2) if 4Ts score as a potential predictor of length of stay and mortality in ICU. As a secondary outcome, we assessed if Body Mass Index (BMI) and Recent Surgery are related to false positive anti-PF4 Ab test. Kruskal-Wallis test and Fisher Exact test were used. Results: A total of 66 patients were identified. The mean age was 64 yr and the male-female ratio was similar. 40 patients had recent surgery in the past 3 months. The cause of thrombocytopenia other than HIT was possible or definite in 62 patients with sepsis being the most common cause (56.45%). 30 patients had low probability 4-Ts scores, 28 had intermediate and 7 had high probability. HIT was confirmed (Serotonin Release Assay-SRA positive) in 0%, 7.14% and 12.5% of patients with low, intermediate and high probability 4Ts scores, respectively. In the patients with low probability 4Ts and anti-PF4 Ab testing, heparin was held in 24 (80%) and the anti-coagulation was switched (to either fondaparinux or argatroban) in 10 (33.33%). In those patients with anticoagulation switch, 3 had minor bleeding. There was no difference in the ICU length of stay (p=0.1712) and mortality (p=0.149) between patients with low, intermediate and high probability 4Ts scores. Patients with BMI ≥40 kg/m2 had twice the percentage of false positive anti-PF4 Ab testing compared with the rest, but the results were not significant (p=0.285). Recent surgery was not related to the false positive anti-PF4 Ab testing (p=1). Conclusion: As no patient with low-probability 4Ts score had confirmed HIT, low 4Ts may be a good estimator of the unlikeliness of HIT even in critically ill patients. We found discrepancy in the recommendations and usage of Anti-PF4 Ab testing in our institution. This has resulted in switching of heparin to other, more expensive anti-coagulations. This may very well be the situation in many other similar institutions. This could partly be due to lack of awareness of HIT testing guidelines in the critical care setting. We recommend the use of 4Ts scoring and more sensible testing and treatment of HIT in ICU patients. Although we could not demonstrate the statistical association between morbid obesity and false positive anti-PF4 Ab, our study might have been underpowered by low subgroup population of such patients. We propose further studies about HIT testing and treatment to include morbidly obese patients as a separate sub-group. Disclosures No relevant conflicts of interest to declare.

A clinical prediction score for upper extremity deep venous thrombosis

2008 ◽  
Vol 99 (01) ◽  
pp. 202-207 ◽  
Author(s):  
Louis-Rachid Salmi ◽  
Marie-Antoinette Sevestre-Pietri ◽  
Sophie Perusat ◽  
Monika Nguon ◽  
Maryse Degeilh ◽  
...  
Keyword(s):  
Venous Thrombosis ◽  
Deep Venous Thrombosis ◽  
Upper Extremity ◽  
High Probability ◽  
Clinical Score ◽  
Prediction Score ◽  
University Hospital ◽  
Clinical Prediction ◽  
Probability Score ◽  
Low Probability

SummaryIt was the objective of this study to design a clinical prediction score for the diagnosis of upper extremity deep venous thrombosis (UEDVT).A score was built by multivariate logistic regression in a sample of patients hospitalized for suspicion of UEDVT (derivation sample). It was validated in a second sample in the same university hospital, then in a sample from the multicenter OPTIMEV study that included both outpatients and inpatients. In these three samples, UEDVT diagnosis was objectively confirmed by ultrasound. The derivation sample included 140 patients among whom 50 had confirmed UEDVT, the validation sample included 103 patients among whom 46 had UEDVT, and the OPTIMEV sample included 214 patients among whom 65 had UEDVT. The clinical score identified a combination of four items (venous material, localized pain, unilateral pitting edema and other diagnosis as plausible). One point was attributed to each item (positive for the first 3 and negative for the other diagnosis). A score of –1 or 0 characterized low probability patients, a score of 1 identified intermediate probability patients, and a score of 2 or 3 identified patients with high probability. Low probability score identified a prevalence of UEDVT of 12, 9 and 13%, respectively, in the derivation, validation and OPTIMEV samples. High probability score identified a prevalence of UEDVT of 70, 64 and 69% respectively. In conclusion we propose a simple score to calculate clinical probability of UEDVT. This score might be a useful test in clinical trials as well as in clinical practice.

scholarly journals Pre-test probability for SARS-Cov-2-related Infection Score: the PARIS score

2020 ◽  
Keyword(s):  
Cell Count ◽  
White Blood Cell Count ◽  
White Blood Cell ◽  
High Probability ◽  
Validation Cohort ◽  
Rt Pcr ◽  
Blood Cell Count ◽  
Probability Score ◽  
Low Probability ◽  
Test Probability

AbstractBackgroundDiagnostic tests for SARS-CoV-2 infection (mostly RT-PCR and Computed Tomography) are not widely available in numerous countries, expensive and with imperfect performanceMethodsThis multicenter retrospective study aimed to determine a pre-test probability score for SARS-CoV-2 infection based on clinical and biological variables. Patients were recruited from emergency and infectious disease departments and were divided into a training and a validation cohort. Demographic characteristics, clinical symptoms, and results of blood tests (complete white blood cell count, serum electrolytes and CRP) were collected. The pre-test probability score was derived from univariate analyses between patients and controls, followed by multivariate binary logistic analysis to determine the independent variables associated with SARS-CoV-2 infection. Points were assigned to each variable to create the PARIS score. ROC curve analysis determined the area under the curve (AUC).FindingsOne hundred subjects with clinical suspicion of SARS-CoV-2 infection were included in the training cohort, and 300 other consecutive individuals were included in the validation cohort. Low lymphocyte (<1·3 G/L), eosinophil (<0·06G/L), basophil (<0·04G/L) and neutrophil counts (<5G/L) were associated with a high probability of SARS-CoV-2 infection. No clinical variable was statistically significant. The score had a good performance in the validation cohort (AUC=0.889 (CI: [0.846–0.932]; STD=0.022) with a sensitivity and Positive Predictive Value of high-probability score of 80·3% and 92·3% respectively. Furthermore, a low-probability score excluded SARS-CoV-2 infection with a Negative Predictive Value of 99.5%.InterpretationThe PARIS score based on complete white blood cell count has a good performance to categorize the pre-test probability of SARS-CoV-2 infection. It could help clinicians avoid diagnostic tests in patients with a low-probability score and conversely keep on testing individuals with high-probability score but negative RT-PCR or CT. It could prove helpful in countries with a low-availability of PCR and/or CT during the current period of pandemic.FundingNonePutting research into contextEvidence before this studyIn numerous countries, large population testing is impossible due to the limited availability and costs of RT-PCR kits and CT-scan. Furthermore, false-negativity of PCR or CT as well as COVID-19 pneumonia mimickers on CT may lead to inaccurate diagnoses. Pre-test probability combining clinical and biological features has proven to be a particularly useful tool, already used in clinical practice for management of patients with a suspicion of pulmonary embolism.Added value of this studyThis retrospective study including 400 patients with clinical suspicion of SARS-CoV-2 infection was composed of a training and a validation cohort. The pre-test probability score (PARIS score) determines 3 levels of probability of SARS-CoV2 infection based on white blood cell count (lymphocyte, eosinophil, basophil and neutrophil cell count).Implications of the available evidenceThis pre-test probability may help to adapt SARS-CoV-2 infection diagnostic tests. The high negative predictive value (99·5%) of the low probability category may help avoid further tests, especially during a pandemic with overwhelmed resources. A high probability score combined with typical CT features can be considered sufficient for diagnosis confirmation.

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 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.

Safety and Feasibility of a Diagnostic Algorithm Combining Clinical Probability, D-Dimer and Ultrasonography in Suspected Upper Extremity Deep Vein Thrombosis: A Prospective Management Study

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 391-391
Author(s):  
Ankie Kleinjan ◽  
Marcello Di Nisio ◽  
Jan Beyer-Westendorf ◽  
Benilde Cosmi ◽  
Giuseppe Camporese ◽  
...  
Keyword(s):  
Pulmonary Embolism ◽  
Upper Extremity ◽  
High Probability ◽  
Diagnostic Algorithm ◽  
Clinical Decision ◽  
Probability Score ◽  
Vein Thrombosis ◽  
Low Probability ◽  
D Dimer ◽  
Compression Ultrasonography

Abstract Abstract 391 Introduction Traditionally, the focus of VTE diagnostic is on deep vein thrombosis (DVT) of the leg and pulmonary embolism. Until recently, upper extremity DVT (UEDVT) was regarded as an uncommon and relatively benign presentation of venous thromboembolism; however, the more widespread use of central venous catheters has caused a significant increase in its incidence. Moreover, recent data indicate that 10–25% of these patients may have pulmonary embolism. Therefore, effective and safe diagnostic strategies are needed. The use of an algorithm combining a clinical decision score, D-dimer and ultrasonography is well-established for suspected lower limb DVT, but has not been evaluated in suspected UEDVT. This diagnostic management study assessed the safety and feasibility of a new diagnostic algorithm in patients with clinically suspected UEDVT. Methods In- and outpatients with suspected UEDVT were recruited from January 2010 until July 2012 in 17 hospitals in Europe and the United States. To confirm an acceptable failure rate of excluding UEDVT (upper 95% confidence interval below 3%), approximately 400 patients needed to be included. Main exclusion criteria were previous UEDVT and the use of therapeutic doses of anticoagulants. Informed consent was obtained from all participants. The algorithm consisted of the sequential application of the Constans' clinical decision score (Constans et al, Thromb Haemost 2008), D-dimer testing and compression ultrasonography. Patients were first categorized as UEDVT likely or unlikely by the Constans' score. In the patients with an unlikely score and a normal D-dimer, UEDVT was considered excluded and no further testing was done. All other patients underwent compression ultrasonography, which first assessed the deep veins for the presence of UEDVT and then the superficial veins for the presence of superficial vein thrombosis (SVT). Ultrasonography was repeated in case of an indeterminate ultrasonography result, or in patients with a high probability score, abnormal D-dimer and a normal ultrasonography. The primary outcome was the 3-month incidence of symptomatic UEDVT and pulmonary embolism in patients with a diagnostic work-up excluding both UEDVT and SVT. Results The study population comprised of 356 consecutive patients with suspected UEDVT. The algorithm was feasible and completed in 96% (Figure). Of the 356 patients, 181 had a low probability score and D-dimer was measured. In 78 patients (22%) a normal D-dimer combined with a low probability score excluded UEDVT without any imaging, and these patients all had an uneventful 3 month follow up. An abnormal D-dimer test result was found in 100 patients, who underwent ultrasonography. In 3 patients, D-dimer measurement was not done, and these patients received ultrasonography right away. Of all patients with a low probability score, 15 patients had UEDVT, 24 patients had SVT, while thrombosis (both deep and superficial) was excluded in 141 patients. One remaining patient died of progressive cancer before ultrasonography could be done. All 175 patients with a high probability score underwent compression ultrasonography right away, which was repeated if indicated. Of these patients with a high probability score, 82 had UEDVT and 22 had SVT. In 71 patients, thrombosis was excluded, including 11 patients in whom the protocol was not followed completely. To summarize, of the 356 included patients, 97 patients had UEDVT (27%), 46 had SVT (13%) and in 212 patients the algorithm excluded UEDVT and SVT (60%). Of all patients in whom the algorithm excluded UEDVT and SVT, one patient developed UEDVT during follow-up for an overall failure rate of 0.47% (95%CI: 0.0–2.6%). Final results of the definitive study population of 407 patients will be presented. Conclusions A new diagnostic algorithm which combines a clinical decision score, D-dimer and ultrasonography can safely and effectively exclude venous thrombosis of the upper extremity. This approach is attractive as it is simple, quick and non-invasive, and very similar to the well established algorithm for suspected DVT of the leg which could facilitate its implementation in clinical practice. Disclosures: No relevant conflicts of interest to declare.

Spatial suppression due to statistical regularities is driven by distractor suppression not by target activation

2018 ◽  
Author(s):  
Michel Failing ◽  
Benchi Wang ◽  
Jan Theeuwes
Keyword(s):  
High Probability ◽  
Target Location ◽  
Target Selection ◽  
Visual Space ◽  
Alternative Interpretation ◽  
Distractor Location ◽  
Target Presentation ◽  
Statistical Regularities ◽  
Low Probability ◽  
Presentation Experiment

Where and what we attend to is not only determined by what we are currently looking for but also by what we have encountered in the past. Recent studies suggest that biasing the probability by which distractors appear at locations in visual space may lead to attentional suppression of high probability distractor locations which effectively reduces capture by a distractor but also impairs target selection at this location. However, in many of these studies introducing a high probability distractor location was tantamount to increasing the probability of the target appearing in any of the other locations (i.e. the low probability distractor locations). Here, we investigate an alternative interpretation of previous findings according to which attentional selection at high probability distractor locations is not suppressed. Instead, selection at low probability distractor locations is facilitated. In two visual search tasks, we found no evidence for this hypothesis: neither when there was only a bias in target presentation but no bias in distractor presentation (Experiment 1), nor when there was only a bias in distractor presentation but no bias in target presentation (Experiment 2). We conclude that recurrent presentation of a distractor in a specific location leads to attentional suppression of that location through a mechanism that is unaffected by any regularities regarding the target location.

Validation of a machine learned model to predict the diagnosis of myocardial infarction

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
D Doudesis ◽  
J Yang ◽  
A Tsanas ◽  
C Stables ◽  
A Shah ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Coronary Syndrome ◽  
Predictive Value ◽  
High Probability ◽  
Cardiovascular Death ◽  
Gradient Boosting ◽  
Funding Source ◽  
Coronary Syndrome ◽  
Low Probability ◽  
One Year

Abstract Introduction The myocardial-ischemic-injury-index (MI3) is a promising machine learned algorithm that predicts the likelihood of myocardial infarction in patients with suspected acute coronary syndrome. Whether this algorithm performs well in unselected patients or predicts recurrent events is unknown. Methods In an observational analysis from a multi-centre randomised trial, we included all patients with suspected acute coronary syndrome and serial high-sensitivity cardiac troponin I measurements without ST-segment elevation myocardial infarction. Using gradient boosting, MI3 incorporates age, sex, and two troponin measurements to compute a value (0–100) reflecting an individual's likelihood of myocardial infarction, and estimates the negative predictive value (NPV) and positive predictive value (PPV). Model performance for an index diagnosis of myocardial infarction, and for subsequent myocardial infarction or cardiovascular death at one year was determined using previously defined low- and high-probability thresholds (1.6 and 49.7, respectively). Results In total 20,761 of 48,282 (43%) patients (64±16 years, 46% women) were eligible of whom 3,278 (15.8%) had myocardial infarction. MI3 was well discriminated with an area under the receiver-operating-characteristic curve of 0.949 (95% confidence interval 0.946–0.952) identifying 12,983 (62.5%) patients as low-probability (sensitivity 99.3% [99.0–99.6%], NPV 99.8% [99.8–99.9%]), and 2,961 (14.3%) as high-probability (specificity 95.0% [94.7–95.3%], PPV 70.4% [69–71.9%]). At one year, subsequent myocardial infarction or cardiovascular death occurred more often in high-probability compared to low-probability patients (17.6% [520/2,961] versus 1.5% [197/12,983], P&lt;0.001). Conclusions In unselected consecutive patients with suspected acute coronary syndrome, the MI3 algorithm accurately estimates the likelihood of myocardial infarction and predicts probability of subsequent adverse cardiovascular events. Performance of MI3 at example thresholds Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): Medical Research Council

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