Use of a computer-based provider order entry (CPOE) intervention to optimize laboratory testing in patients with suspected heparin-induced thrombocytopenia

Limitations of a platelet count-based clinical decision support system to facilitate diagnosis of heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a rare complication of heparin exposure with potential for significant morbidity and mortality. Early identification and treatment can prevent catastrophic thrombosis. Herein, we report the performance of a platelet count-based clinical decision support system (CDSS) where providers received a notification when a patient had a platelet count decline of ≥50 %. In the 90-day study period, the CDSS sent 302 notifications on 270 patients. Notifications were frequently inappropriate; 25 % had an expected platelet count decline (organ donation, stem cell transplant), an inaccurate count, or no heparin exposure. Patient testing for HIT prompted by the CDSS was not in accordance with best practice guidelines in most circumstances. For example, 36 % had a low probability 4Ts score, while 42 % with an intermediate or high probability 4Ts score were not tested. Due to concern for lack of efficacy, the CDSS was discontinued. Analysis of an 8-month period before and after discontinuation showed a significant decrease in the number of enzyme immunoassays ordered (547 vs. 386) without a change in the number of patients with HIT identified (13 vs. 13) or the rate of thrombosis in those with confirmed HIT (62 % vs. 62 %). In conclusion, a CDSS based on platelet count decline contributed to "alert fatigue" via inappropriate notification and did not improve evidence-based HIT testing. In addition, its removal did not decrease or delay HIT identification. Additional efforts are needed to better define how CDSS can support the rapid diagnosis and appropriate treatment of patients with HIT.

Electronic alerts to improve management of heparin-induced thrombocytopenia

Background

Heparin-induced thrombocytopenia (HIT) is a difficult clinicopathologic diagnosis to make and to treat. Delays in identification and appropriate treatment can lead to increased morbidity and mortality.

Objectives

To use electronic health alert interventions to improve provider diagnosis and management of heparin-induced thrombocytopenia through guideline-based, accurate care delivery.

Methods

This quality improvement initiative developed 3 electronic health record-based interventions at our 750-bed academic medical center to improve the initial management of suspected HIT between 2018 and 2021: 1. an interruptive alert to recommend discontinuation of active heparin products when signing a heparin-platelet factor 4 test (PF4) order, 2. integrated 4T score calculation in the heparin-PF4 test order, and 3. interruptive alert suggesting not to order heparin-PF4 tests when the 4T score is <4. Changes in practice were assessed over defined time periods pre and post each intervention.

Results

Intervention 1 resulted in heparin discontinuation in more patients, with 65% (191 heparin orders/293 heparin-PF4 enzyme-linked immunosorbent assay tests) of cases continuing heparin prealert and only 54% (127 heparin orders/235 heparin-PF4 enzyme-linked immunosorbent assay tests) postinterruptive alert (95% CI 2.3-19.9; P = .015). Intervention 2 increased appropriate heparin-PF4 test ordering from 40.4% (110/272) preintervention to 79.1% (246/311) (95% CI 30.9-46.4; P < .00001) postintervention, with inappropriate PF4 ordering defined as testing when 4T score was <4. Intervention 3 did not lead to reduction in heparin-PF4 testing in the control group (96 inappropriate orders/402 total orders, 24%) compared to the randomized alert group (56 inappropriate orders/298 total orders; 19%) (95% CI -1.2 to 11.5; P = .13).

Conclusion

Implementation of unique electronic health record interventions, including both diagnostic and management interventions, led to improved guideline-based, accurate care delivery with 4T score calculation and cessation of heparin for patients with suspected HIT.

Improving Judicious Use of Heparin-Induced Thrombocytopenia Testing Through Electronic Health Record-Based Intervention

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is an immune-mediated drug reaction that can cause thromboembolism in the setting of thrombocytopenia. An enzyme-linked immunosorbent assay (ELISA)-based assay to screen for HIT antibodies (HAb) is available but has relatively low specificity and a correspondingly high false positive rate. The 4Ts score has been validated to determine the pretest probability of HIT. The authors hypothesized that an electronic health record (EHR)-based clinical decision support (CDS) tool incorporating the 4Ts score would reduce the volume of HAb orders.

METHODS

After implementing a CDS tool into the EHR, the researchers retrospectively evaluated the impact from November 2019 to October 2021, compared to a preintervention period (January to October 2019). The primary outcome was average tests per month. Secondary outcomes included rates of tests ordered per total inpatient encounters and proportion of HAb sent despite low 4Ts score in the postintervention study period.

RESULTS

Of 1,833 HAb sent during the study period, 1,217 occurred in the postintervention period. In the postintervention period compared with the preintervention period, the average orders per month was 50.5 (standard deviation [SD] 9.7) vs. 61.6 (SD 7.2) (p = 0.003), and the order incidence rate was 8.0 per 1,000 patient encounters postintervention vs. 9.2 per 1,000 patient encounters preintervention (rate ratio [RR] 0.87, 95% confidence interval [CI] 0.79-0.96, p = 0.002). Postintervention, 252 (20.7%) had a 4Ts score calculated as low probability, 759 (62.4%) as intermediate probability, and 131 (10.8%) as high probability, and 75 had no associated 4Ts score.

CONCLUSION

Implementation of a simple CDS tool reduced the rate of HAb orders, reducing unnecessary HAb testing.

Quality improvement approaches to heparin-induced thrombocytopenia: a scoping review

Background

Heparin-induced thrombocytopenia (HIT) is a relatively uncommon condition characterized by 2 exceedingly common phenomena in hospitalized patients: thrombocytopenia and heparin exposure. Consequently, HIT is frequently overdiagnosed and inappropriately treated. These issues are the focus of many quality improvement (QI) initiatives.

Objectives

In this scoping review, we identified and characterized all published QI studies on improving the diagnosis and management of HIT.

Methods

We conducted a systematic literature search through April 2022 for studies reporting on QI interventions regarding the diagnosis, treatment, and/or prevention of HIT.

Results

Thirty studies were included in the final review. Studies were separated into 5 groups based on the focus of the interventions: increasing HIT recognition, reducing HIT incidence, reducing HIT overdiagnosis, promoting safer HIT management, and creating HIT task forces. Nine studies focused on the implementation of 4Ts score calculator into electronic medical record orders for HIT testing, while only 1 evaluated the impact of reducing unfractionated heparin use in favor of low-molecular-weight heparin. Six studies focused on the implementation of direct thrombin inhibitor management protocols, while none evaluated the use of alternative anticoagulants in HIT management.

Conclusion

The bulk of published HIT QI research focused on reducing overdiagnosis and promoting safer direct thrombin inhibitor therapy, while minimal attention has been devoted to HIT prevention and the use of evidence-based alternative HIT therapies.

Clinical decision support to reduce unnecessary diagnostic testing for heparin-induced thrombocytopenia

Appropriate evaluation of heparin-induced thrombocytopenia (HIT) is imperative because of the potentially life-threatening complications. However, overtesting and overdiagnosis of HIT are common. Our goal was to evaluate the impact of clinical decision support (CDS) based on the HIT computerized-risk (HIT-CR) score, designed to reduce unnecessary diagnostic testing. This retrospective observational study evaluated CDS that presented a platelet count versus time graph and 4Ts score calculator to clinicians who initiated a HIT immunoassay order in patients with predicted low risk (HIT-CR score 0-2). The primary outcome was the proportion of immunoassay orders initiated but cancelled after firing of the CDS advisory. Chart reviews were conducted to assess anticoagulation usage, 4Ts scores and the proportion of patients who had HIT. In a 20-week period, 319 CDS advisories were presented to users who initiated potentially unnecessary HIT diagnostic testing. The diagnostic test order was discontinued in 80 (25%) patients. Heparin products were continued in 139 (44%) patients, and alternative anticoagulation was not given to 264 (83%). The negative predictive value of the advisory was 98.8% (95% CI: 97.2-99.5). HIT-CR score-based CDS can reduce unnecessary diagnostic testing for HIT in patients with a low pretest probability of HIT.

Heparin-induced thrombocytopenia: An illustrated review

Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse drug effect from unfractionated or low-molecular-weight heparin that results in thrombocytopenia and potentially catastrophic thrombosis. HIT occurs due to the development of platelet-activating antibodies against multimolecular complexes of platelet factor 4 and heparin. Given the frequency of thrombocytopenia and heparin use among hospitalized patients, calculation of the 4Ts Score is recommended to identify patients at increased likelihood of HIT and direct further evaluation. In patients with an intermediate or high probability 4Ts Score, an immunoassay and functional assay are recommended to confirm or refute the diagnosis of HIT. Heparin avoidance and initiation of nonheparin anticoagulation are the mainstays of acute HIT management. In this illustrated review, we provide visual summaries of the diagnosis and management of HIT, highlighting connections between pathophysiology and clinical care as well as summarizing efforts in quality improvement in the field. We further emphasize common pitfalls and pearls in diagnosis and management to encourage evidence-based care. We include graphical representation of the unique challenges of HIT with cardiopulmonary bypass and also delineate autoimmune HIT and its subtypes.

Reducing Inappropriate Simultaneous Ordering of Heparin Antibody and Serotonin Release Assays

INTRODUCTION

A 4T score with intermediate or high probability of heparin-induced thrombocytopenia prompts ordering of anti-platelet 4 heparin complex. If positive, a serotonin release assay (SRA) is recommended to confirm diagnosis. Despite these recommendations, overtesting of both anti-platelet 4 and SRA is highly prevalent.

METHODS

This was a quality improvement initiative using two forms of clinical decision support across 11 acute care hospitals. First, a 4T calculator was incorporated into anti-platelet 4 orders. Second, a Best Practice Advisory fired when anti-platelet 4 and SRA were ordered simultaneously, prompting the provider to remove the SRA order. Data were analyzed by a quasi-experimental interrupted time series linear regression comparing weekly average laboratory tests per 1,000 patient-days pre- and postintervention.

RESULTS

Average ordering frequency of anti-platelet 4 changed from 0.508 to 0.510 per 1,000 patient-days (0.5%, p = 0.42) without significant slope or level differences. Average ordering frequency of SRA decreased from 0.430 to 0.289 per 1,000 patient-days (32.8%, p < 0.001) with a significant level difference of -0.128 orders per 1,000 patient-days (-31.2%, p < 0.05).

CONCLUSION

A simultaneous Best Practice Advisory was effective in reducing SRA orders, but not anti-platelet 4 orders.

Clinical Decision Support for Laboratory Testing

BACKGROUND

As technology enables new and increasingly complex laboratory tests, test utilization presents a growing challenge for healthcare systems. Clinical decision support (CDS) refers to digital tools that present providers with clinically relevant information and recommendations, which have been shown to improve test utilization. Nevertheless, individual CDS applications often fail, and implementation remains challenging.

CONTENT

We review common classes of CDS tools grounded in examples from the literature as well as our own institutional experience. In addition, we present a practical framework and specific recommendations for effective CDS implementation.

SUMMARY

CDS encompasses a rich set of tools that have the potential to drive significant improvements in laboratory testing, especially with respect to test utilization. Deploying CDS effectively requires thoughtful design and careful maintenance, and structured processes focused on quality improvement and change management play an important role in achieving these goals.

Laboratory test ordering in inpatient hospitals: a systematic review on the effects and features of clinical decision support systems

Background

Studies have revealed inappropriate laboratory testing as a source of waste. This review aimed at evaluating the effects and features of CDSSs on physicians' appropriate laboratory test ordering in inpatient hospitals.

Method

Medline through PubMed, SCOPUS, Web of Science, and Cochrane were queried without any time period restriction. Studies using CDSSs as an intervention to improve laboratory test ordering as the primary aim were included. The study populations in the included studies were laboratory tests, physicians ordering laboratory tests, or the patients for whom laboratory tests were ordered. The included papers were evaluated for their outcomes related to the effect of CDSSs which were categorized based on the outcomes related to tests, physician, and patients. The primary outcome measures were the number and cost of the ordered laboratory tests. The instrument from The National Heart Lung and Blood Institute (NIH) was used to assess the quality of the included studies. Moreover, we applied a checklist for assessing the quality and features of the CDSSs presented in the included studies. A narrative synthesis was used to describe and compare the designs and the results of included studies.

Result

Sixteen studies met the inclusion criteria. Most studies were conducted based on a quasi-experimental design. The results showed improvement in laboratory test-related outcomes (e.g. proportion and cost of tests) and also physician-related outcomes (e.g. guideline adherence and orders cancellation). Patient-related outcomes (e.g. length of stay and mortality rate) were not well investigated in the included studies. In addition, the evidence about applying CDSS as a decision aid for interpreting laboratory results was rare.

Conclusion

CDSSs increase appropriate test ordering in hospitals through eliminating redundant test orders and enhancing evidence-based practice. Appropriate testing and cost saving were both affected by the CDSSs. However, the evidence is limited about the effects of laboratory test CDSSs on patient-related outcomes.

A systematic literature review on unnecessary diagnostic testing: The role of ICT use

BACKGROUND

The negative impact of unnecessary diagnostic tests on healthcare systems and patients has been widely recognized. Medical researchers in various countries have been devoting effort to reduce unnecessary diagnostic tests by using different types of interventions, including information and communications technology-based (ICT-based) intervention, educational intervention, audit and feedback, the introduction of guidelines or protocols, and the reward and punishment of staff. We conducted a review of ICT based interventions and a comparative analysis of their relative effectiveness in reducing unnecessary tests.

METHOD

A systematic Boolean search in PubMed, EMBase and EBSCOhost research databases was performed. Keyword search and citation analysis were also conducted. Empirical studies reporting ICT based interventions, and their implications on relative effectiveness in reducing unnecessary diagnostic tests (pathology tests or medical imaging) were evaluated independently by two reviewers based on a rigorously developed coding protocol.

RESULTS

92 research articles from peer-reviewed journals were identified as eligible. 47 studies involved a single-method intervention and 45 involved multi-method interventions. Regardless of the number of interventions involved in the studies, ICT-based interventions were utilized by 71 studies and 59 of them were shown to be effective in reducing unnecessary testing. A clinical decision support (CDS) tool appeared to be the most adopted ICT approach, with 46 out of 71 studies using CDS tools. The CDS tool showed effectiveness in reducing test volume in 38 studies and reducing cost in 24 studies.

CONCLUSIONS

This review investigated five frequently utilized intervention methods, ICT-based, education, introduction of guidelines or protocols, audit and feedback, and reward and punishment. It provides in-depth analysis of the efficacy of different types of interventions and sheds insights about the benefits of ICT based interventions, especially those utilising CDS tools, to reduce unnecessary diagnostic testing. The replicability of the studies is limited due to the heterogeneity of the studies in terms of context, study design, and targeted types of tests.

Validation and Implementation of an Ordering Alert to Improve the Efficiency of Monoclonal Gammopathy Evaluation

OBJECTIVES

To evaluate the use of a provider ordering alert to improve laboratory efficiency and reduce costs.

METHODS

We conducted a retrospective study to assess the use of an institutional reflex panel for monoclonal gammopathy evaluation. We then created a clinical decision support (CDS) alert to educate and encourage providers to change their less-efficient orders to the reflex panel.

RESULTS

Our retrospective analysis demonstrated that an institutional reflex panel could be safely substituted for a less-efficient and higher-cost panel. The implemented CDS alert resulted in 79% of providers changing their high-cost order panel to an order panel based on the reflex algorithm.

CONCLUSIONS

The validated decision support alert demonstrated high levels of provider acceptance and directly led to operational and cost savings within the laboratory. Furthermore, these studies highlight the value of laboratory involvement with CDS efforts to provide agile and targeted provider ordering assistance.

Interventions designed to improve the safety and quality of therapeutic anticoagulation in an inpatient electronic medical record

IMPORTANCE

Anticoagulants are high-risk medications with the potential to cause significant patient harm or death. Digital transformation is occurring in hospital practice and it is essential to implement effective, evidence-based strategies for these medications in an electronic medical record (EMR).

OBJECTIVE

To systematically appraise the literature to determine which EMR interventions have improved the safety and quality of therapeutic anticoagulation in an inpatient hospital setting.

METHODS

PubMed, Embase, CINAHL, and the International Pharmaceutical Database were searched for suitable publications. Articles that met eligibility criteria up to September 2018 were included. The review was registered with PROSPERO (CRD42018104899). The web-based software platform Covidence® was used for screening and data extraction. Studies were grouped according to the type of intervention and the outcomes measured. Where relevant, a bias assessment was performed.

RESULTS

We found 2624 candidate articles and 27 met inclusion criteria. They included 3 randomised controlled trials, 4 cohort studies and 20 pre/post observational studies. There were four major interventions; computerised physician order entry (CPOE) (n = 4 studies), clinical decision support system (CDSS) methods (n = 21), dashboard utilisation (n = 1) and EMR implementation in general (n = 1). Seven outcomes were used to summarise the study results. Most research focused on prescribing or documentation compliance (n = 18). The remaining study outcome measures were: medication errors (n = 9), adverse drug events (n = 5), patient outcomes (morbidity/mortality/length of hospital stay/re-hospitalisation) (n = 5), quality use of anticoagulant (n = 4), end-user acceptance (n = 4), cost effectiveness (n = 1).

CONCLUSION

Despite the research cited, limited benefits have been demonstrated to date. It appears healthcare organisations are yet to determine optimal, evidence-based-methods to improve EMR utilisation. Further evaluation, collaboration and work are necessary to measure and leverage the potential benefits of digital health systems. Most research evaluating therapeutic anticoagulation management within an EMR focused on prescribing or documentation compliance, with less focus on clinical impact to the patient or cost effectiveness. Evidence suggests that CPOE in conjunction with CDSS is needed to effectively manage therapeutic anticoagulation. Targets for robust research include the integration of 'stealth' alerts, nomograms into digital systems and the use of dashboards within clinical practice.

Decision Support Tools within the Electronic Health Record

Laboratory tests are an integral part of the electronic health record (EHR). Providing clinical decision support (CDS) for the ordering, collection, reporting, viewing, and interpretation of laboratory testing is a fundamental function of the EHR. The implementation of a sustainable, effective laboratory CDS program requires a commitment to standardization and harmonization of the laboratory dictionaries that are the foundation of laboratory-based CDS. In this review, the authors provide an overview of the tools available within the EHR to improve decision making throughout the entire laboratory testing process, from test order to clinical action.

Limited impact of clinician education on reducing inappropriate PF4 testing for heparin-induced thrombocytopenia

A high frequency of PF4-ELISA testing in patients suspected to have heparin-induced thrombocytopenia (HIT) despite low 4T scores has been observed in multiple medical centers. Education of clinicians has been suggested to reduce inappropriate testing. We determined trends of PF4-ELISA testing in our institution after the introduction of a HIT education program for clinicians. A HIT Program was developed that included ongoing education, individual feedback, and continuous clinical audit of PF4-ELISA utilization. To assess the impact of education on PF4-ELISA testing trends, we conducted a prospective cohort review of all adult patients who had a PF4-ELISA ordered over a 3 month period (the last quarter of the academic year). 72 PF4-ELISA tests were ordered during the study period. Prospectively calculated 4T scores by investigators revealed 60 low-risk (83.3%), 9 intermediate-risk (12.5%), and 3 high-risk (4.16%). We observed divergent 4T scores with the ordering clinician calculating a higher 4T score compared to the Hematology Quality Improvement (QI) team. The majority of PF4-ELISA testing was ordered by the intensive care units (ICUs) (n = 32, 44.44%). Our study revealed that the frequency of calculation of 4T scores remains poor with the majority inappropriately performed in the ICU setting, with ordering clinicians calculating higher 4T scores than the Hematology QI team. This suggests that clinician education alone is insufficient. Introducing mandatory 4T score calculation prior to PF4-ELISA testing may not be helpful as ordering clinicians can bypass the restriction through inaccurate 4T score calculation.

Effectiveness of Practices to Support Appropriate Laboratory Test Utilization: A Laboratory Medicine Best Practices Systematic Review and Meta-Analysis

Objectives

To evaluate the effectiveness of practices used to support appropriate clinical laboratory test utilization.

Methods

This review followed the Centers for Disease Control and Prevention (CDC) Laboratory Medicine Best Practices A6 cycle method. Eligible studies assessed one of the following practices for effect on outcomes relating to over- or underutilization: computerized provider order entry (CPOE), clinical decision support systems/tools (CDSS/CDST), education, feedback, test review, reflex testing, laboratory test utilization (LTU) teams, and any combination of these practices. Eligible outcomes included intermediate, systems outcomes (eg, number of tests ordered/performed and cost of tests), as well as patient-related outcomes (eg, length of hospital stay, readmission rates, morbidity, and mortality).

Results

Eighty-three studies met inclusion criteria. Fifty-one of these studies could be meta-analyzed. Strength of evidence ratings for each practice ranged from high to insufficient.

Conclusion

Practice recommendations are made for CPOE (specifically, modifications to existing CPOE), reflex testing, and combined practices. No recommendation for or against could be made for CDSS/CDST, education, feedback, test review, and LTU. Findings from this review serve to inform guidance for future studies.

Initial and long term impact of a multi-disciplinary task force in the diagnosis and management of heparin-induced thrombocytopenia

Many medical centers are faced with a major challenge in making an accurate diagnosis of heparin-induced thrombocytopenia (HIT) and ensuring appropriate changes in management strategy in line with guideline recommendations. We report the initial and long-term impact and challenges of institution-wide changes in the diagnosis and management of HIT in the inpatient setting at an academic medical center. We established a HIT Task Force, consisting of a multidisciplinary team of non-malignant hematologists, nursing, pharmacist, pathology, blood bank and clinical lab informatics. Changes were implemented from 2011 to 2012. In 2013, testing for PF4 and SRA decreased by 37.5 and 85%, respectively. 100% of positive PF4 received an automatic hematology consult to guide management, leading to a 78% reduction in the use of direct thrombin inhibitors. Annual audits in the subsequent years demonstrated increasing testing for HIT due to changes in the electronic ordering system. Through continuous monitoring, these shortfalls were detected and intervene early on with continued success. The implementation of a centralized hospital-wide protocol via a multidisciplinary task force that coordinates testing and treatment of patients suspected of having HIT led to a substantial reduction in PF4 and SRA testing, as well as use of DTIs, resulting in a safe and cost-effective approach for the diagnosis and treatment of HIT. Our study highlights the important of continuous monitoring to maintain the improvements made. Despite our initial success, annual re-auditing allowed for early detection of challenges, which then allowed appropriate early intervention.

Management of heparin-induced thrombocytopenia

PURPOSE OF REVIEW

The purpose of this review is to summarize recent findings on heparin-induced thrombocytopenia (HIT), a prothrombotic disorder caused by platelet-activating IgG targeting platelet factor 4 (PF4)/polyanion complexes.

RECENT FINDINGS

HIT can explain unusual clinical events, including adrenal hemorrhages, arterial/intracardiac thrombosis, skin necrosis, anaphylactoid reactions, and disseminated intravascular coagulation. Sometimes, HIT begins/worsens after stopping heparin ('delayed-onset' HIT). Various HIT-mimicking disorders are recognized (e.g., acute disseminated intravascular coagulation/'shock liver' with limb ischemia). HIT has features of both B-cell and T-cell immune responses; uptake of PF4/heparin complexes into macrophages ('macropinocytosis') facilitates the anti-PF4/heparin immune response. Antibody-induced activation of monocytes and platelets via their FcγIIA receptors triggers an intense procoagulant response. Sometimes, HIT antibodies recognize PF4 bound to (platelet-associated) chondroitin sulfate, explaining how HIT might occur without concurrent or recent heparin (delayed-onset HIT, 'spontaneous HIT syndrome'). The molecular structure of HIT antigen(s) has been characterized, providing a rationale for future drug design to avoid HIT and improve its treatment. The poor correlation between partial thromboplastin time and plasma argatroban levels (risking subtherapeutic anticoagulation) and need for intravenous administration of argatroban have led to increasing 'off-label' treatment with fondaparinux or one of the direct oral anticoagulants.

SUMMARY

Understanding the molecular mechanisms and unusual clinical features of HIT will improve its management.

Clinical outcomes in a cohort of patients with heparin-induced thrombocytopenia

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is a thrombotic disorder usually prompting treatment with non-heparin anticoagulants. The benefits and risks of such treatments have not been fully assessed.

METHODS

We analyzed data for 442 patients having a positive heparin-platelet factor 4 antibody test and recent heparin exposure. The primary outcome was a composite endpoint (death, limb amputation/gangrene, or new thrombosis). Secondary outcomes included bleeding and the effect of anticoagulation.

FINDINGS

Seventy-one patients (16%) had HIT with thrombosis (HIT-T); 284 (64%) had HIT without thrombosis (isolated HIT); 87 (20%) did not have HIT. An intermediate or high "4T" score was found in 85%, 58%, and 8% of the three respective groups. Non-heparin anticoagulation was begun in 80%, 56%, and 45%. The composite endpoint occurred in 48%, 36%, and 17% (P = .01) of which 61%, 38%, and 40% were receiving non-heparin anticoagulation. Compared with the no HIT group, the composite endpoint was significantly more likely in HIT-T [HR 2.48 (1.35-4.55), P = .003)] and marginally more likely in isolated HIT [HR 1.66 (0.96-2.85), P = .071]. Importantly, risk increased (HR 1.77, P = .02) after platelet transfusion. Major bleeding occurred in 48%, 36%, and 16% of the three groups (P = .005). Non-heparin anticoagulation was not associated with a reduction in composite endpoint events in either HIT group.

INTERPRETATION

HIT patients have high risks of death, limb amputation/gangrene, thrombosis, and bleeding. Non-heparin anticoagulant treatment may not benefit all patients and should be considered only after careful assessment of the relative risks of thrombosis and bleeding in individual patients.

Heparin-induced thrombocytopenia: research and clinical updates

Heparin-induced thrombocytopenia (HIT) remains an important diagnosis to consider in hospitalized patients developing thrombocytopenia. HIT is an immune-mediated prothrombotic disorder caused by antibodies to platelet factor 4 (PF4) and heparin. Recent basic scientific studies have advanced our understanding of disease pathogenesis through studies of the PF4/heparin structure, immune mechanisms, and cellular basis of thrombosis. Clinical advances have also occurred in areas of HIT prevention, description of disease variants, and diagnostic strategies. Emerging anticoagulants with the potential to change HIT treatment are evolving, although with limited data. This review will provide a current perspective on HIT pathogenesis, disease features, diagnostic strategies, and role of emerging therapies for the management of HIT.