Cost-effectiveness of anticoagulants for suspected heparin-induced thrombocytopenia in the United States

The Impact of an Antithrombotic Stewardship Program on Heparin-Induced Thrombocytopenia Management

Background: An antithrombotic stewardship program was implemented to reduce IV DTI use and increase fondaparinux and direct oral anticoagulant (DOAC) use for suspected or confirmed Heparin-induced thrombocytopenia (HIT). Objectives: This study evaluated the impact of an antithrombotic stewardship program on IV DTI utilization in patients with HIT. Methods: A retrospective analysis of adults receiving IV DTIs or fondaparinux from July 2016 to July 2017 (pre-stewardship) and October 2017 to July 2019 (post-stewardship) was conducted. Results: The median duration of IV DTI administration was not significantly different in HIT-negative patients between the pre- and post-stewardship cohorts (1.6 days (25th percentile (p25), 75th percentile (p75): .5, 3.3) vs 1.7 days (p25, p75: .9, 3.9), P = .31). The median duration of IV DTI administration in HIT-positive patients was 9.9 days (p25, p75: 7.6, 21.0) pre-stewardship and 7.3 days (p25, p75: 4.8, 16.5) post-stewardship (P = .18). For HIT-positive patients, the time from HIT diagnosis to discharge was 12.8 days (p25, p75: 8.9, 24.9) and 9.2 days (p25, p75: 4.0, 18.1) in the pre- and post-stewardship cohorts, respectively (P = .07). Fondaparinux and DOAC prescribing rates were 40.7% and 62.2% in the pre- and post-stewardship cohorts, respectively (P = .09). The percentage of patients with no contraindications to IV DTI alternatives receiving these agents increased from 31.2% to 78.6% (P = .01) following stewardship implementation. Conclusions: Intravenous DTI alternative utilization increased significantly after stewardship implementation. Stewardship implementation was associated with a non-statistically significant trend towards decreased IV DTI utilization and decreased length of stay for HIT-positive patients.

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.

Efficacy and safety of Agatroban in improving the prognosis of ischemic stroke patients

OBJECTIVE

To explore and analyze the efficacy and safety of combined treatment of Agatroban and Aspirin in improving short-term and long-term prognosis of ischemic stroke patients.

METHODS

In this retrospective study, the clinical data of patients with ischemic stroke admitted to the Department of Neurology, Songjiang Sijing Hospital from June 2021 to April 2023 were analyzed. A total of 108 patients were selected according to the inclusion and exclusion criteria, including 54 patients treated with Aspirin only, named the control group, and 54 patients treated with Agatroban plus Aspirin, named the study group.

RESULTS

Compared with the control group, the study group had a higher effective rate (P=0.047). There was no significant difference in MIESSS and daily living ability scores between the two groups before treatment (P>0.05). After treatment, compared with the control group, the study group had a lower MIESSS score and a higher daily living ability score (P=0.035; P=0.044). There was no significant difference in coagulation indicators between the two groups before treatment (P>0.05). After treatment, compared with the control group, the study group had lower platelet count, fibrinogen, and D-dimer levels (P=0.031; P=0.042; P=0.047). There was no significant difference in inflammatory cytokines between the two groups before treatment (P>0.05). After treatment, compared with the control group, the study group showed significantly decreased tumor necrosis factor (TNF)-α, interleukin-6 (IL-6) and interleukin-8 (IL-8) (P=0.041; P=0.038; P=0.046). Compared with the control group, the incidence of adverse reactions in the study group was lower (P=0.033), while the prognosis was better (P=0.029; P=0.033; P=0.048).

CONCLUSION

Compared with Aspirin alone, Argatroban plus Aspirin can optimize coagulation parameters to a greater extent and reduce the level of cellular inflammatory factors, further improve the body's neurological functions, remarkably reduce the occurrence of adverse prognosis, and enhance the patient's ability of daily living, with remarkable therapeutic effect.

Use of fondaparinux in patients with heparin-induced thrombocytopenia on veno-venous extracorporeal membrane oxygenation: A three-patient case series report

Heparin-induced thrombocytopenia is a life-threatening immune-mediated complication of unfractionated heparin therapy. Fondaparinux is a therapeutic alternative, but it has limited evidence for its use in patients on extracorporeal membrane oxygenation (ECMO). We present a series of three adult patients with COVID-19 on ECMO who were diagnosed with heparin-induced thrombocytopenia after 7-12 days of unfractionated heparin treatment and were switched to fondaparinux. Fondaparinux was initiated with an intravenous loading dose of 5 mg, followed by a dose of 2.5 mg subcutaneously every 8-12 h. Dosage was adjusted according to daily measured anti-Xa concentration with a target range of 0.4-0.7 mg/L. The total duration of treatment with fondaparinux and ECMO ranged from 13 to 26 days. One major bleeding episode unrelated to fondaparinux therapy was observed, and the transfusions requirement was also low in all patients. The ECMO circuit was changed once in each patient. This series provides a deep insight into the use of fondaparinux over an extended period of time in patients on ECMO. Based on the presented data, fondaparinux can be considered a reasonable and affordable anticoagulant in patients without a high risk of bleeding.

Cost-effectiveness analysis of alternative anticoagulation in suspected heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a life-threatening complication associated with high medical costs. Factor Xa inhibitors have gradually replace approved treatment with intravenous direct thrombin inhibitors despite their off-label indication, because of easier management and favorable economic profile.Whether they are cost-effective remains unclear. We evaluated the cost-effectiveness of approved and off-label anticoagulants in patients with suspected HIT, based on census data from the largest Swiss hospital between 2015 and 2018. We constructed a decision tree model that reflects important clinical events associated with HIT. Relevant cost data were obtained from the finance department or estimated based on the Swiss-wide cost tariff. We estimated averted adverse events (AE) and incremental cost-effectiveness ratio as primary outcome parameters. We performed deterministic and probabilistic sensitivity analyses with 2000 simulations to assess the robustness of our results. In the base-case analysis, the total cost of averting one AE was 49,565 CHF for argatroban; 30,380 CHF for fondaparinux, and 30,610 CHF for rivaroxaban; after adjusting for 4Ts score: 41,152 CHF (argatroban); 27,710 CHF (fondaparinux) and 37,699 CHF (rivaroxaban). Fondaparinux and rivaroxaban were more clinically-effective than argatroban with AE averted of 0.820; 0.834 and 0.917 for argatroban, fondaparinux and rivaroxaban, respectively. Treatment with fondaparinux resulted in less cost and more AE averted, hence dominating argatroban. Results were most sensitive to AE rates and prolongation of stay. Monte Carlo simulations affirmed our base-case analysis. This is the first cost-effectiveness analysis comparing argatroban with fondaparinux and rivaroxaban using primary data. Fondaparinux and rivaroxaban resulted in more averted AE but fondaparinux had greater cost savings. Fondaparinux could be a viable alternative to argatroban.

Minimizing cost associated with management of heparin-induced thrombocytopenia: A cost analysis of various laboratory testing models

INTRODUCTION

Management of patients with suspected heparin-induced thrombocytopenia (HIT) can lead to significant costs. Reported cost-saving initiatives have focused on minimizing inappropriate testing in low-risk patients and optimizing alternative anticoagulant selection. We sought to further investigate how utilizing various HIT laboratory testing models would impact total cost of testing and alternative anticoagulant use.

METHODS

Utilizing a retrospective cohort of adult patients tested for HIT over three years within our institution, we evaluated how utilization of four distinct laboratory models impacted total number of HIT test combinations completed, time to HIT testing finalization, percentage of patients discharged from the hospital prior to HIT testing finalization, total alternative anticoagulant days, and total anticipated major bleed events. Additionally, we calculated cost of laboratory testing and alternative anticoagulant associated with each model.

RESULTS

A total of 482 patients were included in our cohort. A laboratory testing model that utilized an in-house platelet factor 4 (PF4)-heparin enzyme-linked immunosorbent assay (ELISA) completed three days weekly, and reflex serotonin release assay (SRA) with a five-day turnaround resulted in the shortest mean time to HIT testing finalization, lowest percentage of patients discharged prior to HIT testing finalization, and lowest total alternative anticoagulant days.

CONCLUSIONS

Institutions should evaluate current HIT laboratory testing practices and assess for opportunities for optimization. Testing models utilizing a PF4-heparin antibody ELISA with a reflex SRA for positive results may improve testing metrics and lead to lower utilization of alternative anticoagulants.

Comparative effectiveness and safety of anticoagulants for the treatment of heparin-induced thrombocytopenia

BACKGROUND

The effectiveness and safety of non-heparin anticoagulants for the treatment of heparin-induced thrombocytopenia (HIT) are not fully established, and the optimal treatment strategy is unknown. In a systematic review and meta-analysis, we aimed to determine precise rates of platelet recovery, new or progressive thromboembolism (TE), major bleeding, and death for all non-heparin anticoagulants and to study potential sources of variability.

METHODS

Following a detailed protocol (PROSPERO: CRD42020219027), EMBASE and Medline were searched for all studies reporting clinical outcomes of patients treated with non-heparin anticoagulants (argatroban, danaparoid, fondaparinux, direct oral anticoagulants [DOAC], bivalirudin, and other hirudins) for acute HIT. Proportions of patients with the outcomes of interest were pooled using a random-effects model for each drug. The influence of the patient population, the diagnostic test used, the study design, and the type of article was assessed.

RESULTS

Out of 3194 articles screened, 92 studies with 119 treatment groups describing 4698 patients were included. The pooled rates of platelet recovery ranged from 74% (bivalirudin) to 99% (fondaparinux), TE from 1% (fondaparinux) to 7% (danaparoid), major bleeding from 1% (DOAC) to 14% (bivalirudin), and death from 7% (fondaparinux) to 19% (bivalirudin). Confidence intervals were mostly overlapping, and results were not influenced by patient population, diagnostic test used, study design, or type of article.

DISCUSSION

Effectiveness and safety outcomes were similar among various anticoagulants, and significant factors affecting these outcomes were not identified. These findings support fondaparinux and DOACs as viable alternatives to conventional anticoagulants for treatment of acute HIT in clinical practice.

Thrombolysis and use of argatroban for the treatment of massive pulmonary embolism following anticoagulation failure in a patient with COVID-19

Purpose

Successful use of alteplase and argatroban to treat a patient with coronavirus disease 2019 (COVID-19)–associated massive pulmonary embolism with cardiac arrest is reported.

Summary

This case report describes a 42-year-old male with COVID-19 who developed a massive pulmonary embolism resulting in cardiac arrest after suspected failure of low-molecular-weight heparin therapy for a deep venous thrombosis. Administration of two 50-mg doses of intravenous alteplase resulted in return of spontaneous circulation, and low-dose argatroban was used as follow-up anticoagulation therapy without complications. This is the first case report of use of argatroban in a patient with COVID-19 with cardiac arrest–associated massive pulmonary embolism after failure of previous anticoagulation efforts.

Conclusion

Argatroban may be used as an alternate anticoagulation strategy in COVID-19 patients who fail low-molecular weight therapy. A risk versus benefit discussion should be had regarding appropriateness of therapy as well as dosing. More data is needed to understand the unique hypercoagulable condition in COVID-19 patients as well as research that further highlights the role of argatroban and bivalirudin therapy in this patient population.

Efficiency and safety evaluation of prophylaxes for venous thrombosis after gynecological surgery

BACKGROUND

In this study, we investigate the incidence of venous thrombosis (VT), and evaluate the effectiveness and safety of 3 major thromboprophylaxes and the potential risk factors for VT in women undergoing surgery for a gynecological malignancy.

METHODS

We performed a randomized controlled trial of 307 patients undergoing laparoscopic surgery for gynecological malignancies at a single institution from January 2016 to October 2017. Patients were divided into 3 groups: one receiving a half dose of low-molecular-weight heparin sodium injection (FLUXUM, Alfa Wassermann, Italy) delivered by injection, one receiving a full dose of FLUXUM, and a third group receiving an Argatroban injection.

RESULTS

None of the patients in our study developed a pulmonary embolism, bleeding, or infectious complications. There were no statistical differences in the rate of deep venous thrombosis (DVT) (0%, 0%, and 2.38%) and the superficial venous thromboembolism (SVT) (15.66%, 8.97%, and 18.6%) among the 3 groups. None of the patients developed symptomatic VT. The effect of treatment on alanine aminotransferase and aspartate aminotransferase differed between the groups, with a minimal effect in the Argatroban group, and all 3 methods resulted in minimal impairment of renal function. Decreased hemoglobin, elevated levels of D-dimer, and prothrombin time were closely related to thrombogenesis.

CONCLUSION

In conclusion, the incidence of postoperative thrombosis in gynecological malignancy among these Chinese people is not as low as we had originally presumed. Argatroban is not more effective than Parnaparin as a direct thrombin inhibitor, but it has less influence on liver function, which is beneficial for patients undergoing chemotherapy. Hemoglobin, D-dimer, and prothrombin time may be used to predict or detect thrombogenesis.

Potential impact of a delayed ADAMTS13 result in the treatment of thrombotic microangiopathy: an economic analysis

BACKGROUND

A pre-plasma exchange ADAMTS13 measurement differentiates thrombotic thrombocytopenic purpura (TTP) from other forms of thrombotic microangiopathy (TMA). Given that many hospitals do not perform the ADAMTS13 assay in-house and that the turnaround time (TAT) differs among reference laboratories, we performed an analysis investigating the potential impact of a delay in obtaining the results on the healthcare system.

METHODS

An economic model was developed to estimate the impact of a delay in obtaining the pretreatment ADAMTS13 results on patients admitted with TMA with cost (US dollars) as the primary outcome. Incremental cost-effectiveness ratio (ICER) as a composite outcome was calculated from both cost and life days [LDs], an effectiveness surrogate marker. Model parameters were gathered from the medical literature, except for the institutional cost of the ADAMTS13 test.

RESULTS

In patients with TMA, during the 6-day study period, the incremental cost to the healthcare system ranged from approximately $4155 to $5123 for every 1-day delay in obtaining the pre-exchange ADAMTS13 results with virtually no change in the effectiveness marker. The ICER composite outcome established the cost-effectiveness of having a fast TAT for pre-exchange ADAMTS13 results. Probabilistic sensitivity analyses also confirmed the robustness of the model.

CONCLUSIONS

In patients with clinical presentations of TMAs, having a rapid TAT for pre-exchange ADAMTS13 measurement appeared to be cost-effective. If testing cannot be performed in-house, then our findings support the necessity of contracting with a reference laboratory that can reliably provide the result, preferably within 1 day of admission.

Comparison of polyspecific versus IgG specific ELISA in predominately cardiac patients with suspected heparin induced thrombocytopenia

A diagnosis of heparin induced thrombocytopenia (HIT) must often be made based on clinical and laboratory evidence. This was a quasi-experimental study of patients admitted from June 2016 to October 2017. The primary endpoint was the incidence of false positive results in polyspecific and IgG specific enzyme-linked immunosorbent assay (ELISA); then we compared the sensitivity and specificity of each assays in predominately cardiac patients with suspected HIT. A sensitivity/specificity analysis was conducted using serotonin release assay (SRA) as the 'gold standard'. The secondary outcome measures included length of hospital stay. We identified a total of 155 patients who met the inclusion criteria. Confirmatory tests with SRA on both groups were completed; false positive result was higher in the polyspecific group when compared to the IgG group [60% vs. 5%]. The IgG specific ELISA test yielded a sensitivity of 100% and a specificity of 95% however, the polyspecific ELISA had a low yield for specificity of 24% but maintained 100% sensitivity. In the IgG specific group with HIT-, their median length of stay was halved compared to those who were HIT + ; hospital LOS in days, IQR [30 (27-81) vs. 15 (7-33) p = 0.023] and a shorter median LOS in the ICU, IQR [24 (5-47) vs. 6 (2-14); p = 0.079]. Hospital or ICU LOS was the same in both (HIT+ and HIT-) groups managed with polyspecific ELISA. The IgG specific test had few false positive results and a high sensitivity score. Ensuring appropriate testing can bring a substantial decrease in drug expenditure, reduced length of stay and prevent unnecessary anticoagulation.

Potential Role of Direct Oral Anticoagulants in the Management of Heparin-induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a rare, potentially life-threatening condition secondary to unfractionated heparin or low molecular weight heparin exposure. This immune-mediated drug reaction manifests as thrombocytopenia with a paradoxical hypercoagulable state that can result in life-threatening thrombosis. It is imperative to ensure cessation of heparin-based products as soon as HIT is identified. Traditional treatment options include argatroban, bivalirudin, fondaparinux, and danaparoid with a transition to warfarin upon platelet recovery. These anticoagulants are notwithstanding limitations including parenteral administration and routine laboratory monitoring leading to prolonged hospitalizations, emphasizing the need for new therapies. Direct oral anticoagulants (DOACs) have been increasingly investigated for the management of HIT and may overcome the aforementioned challenges of current therapies. The objective of this narrative review is to summarize the current HIT guidelines, discuss limitations to contemporary treatment options, provide insight into the emerging evidence for the DOACs rivaroxaban, apixaban, and dabigatran, and conclude with a clinical summary for their use in this setting. The PubMed, Google Scholar, and MEDLINE databases were searched for peer-reviewed literature from January 1, 2012, to June 31, 2018. Twenty-seven articles met inclusion criteria for review: 1 prospective trial, 5 retrospective cohort studies, and 21 case reports totaling 104 patients treated with a DOAC for HIT. The DOACs prevented new and recurrent thrombosis in 98% (n=102) of cases, and bleeding complications occurred in 3% (n=3). While current literature remains limited, it is suggestive of a potential role of DOACs for HIT, which has led to their integration into the 2018 American Society Hematology Guidelines with a conditional recommendation.

Monitoring Fondaparinux in the Setting of Antithrombin Deficiency

Heparin-induced thrombocytopenia (HIT) is a not-uncommon adverse effect of heparin exposure, with potentially serious and/or fatal thrombotic consequences. Recent studies looking at the off-label use of fondaparinux for HIT show similar efficacy and adverse-effect profiles, as well as improved costs, compared with some commonly used direct thrombin inhibitors. Although routine laboratory monitoring of fondaparinux-specific anti-Xa levels typically is not recommended, we present a case report that suggests fondaparinux monitoring may be needed in patients with hepatic impairment causing acquired antithrombin deficiency. We performed daily assessment of antithrombin- and fondaparinux-specific anti-Xa levels in a 50-year-old female of unknown ethnicity to ensure that fondaparinux dosing was maintained within an acceptable range. With this management strategy, the patient experienced no thrombotic or hemorrhagic complications during the hospital admission or the following 2 months in outpatient treatment.

Pharmacogenetics to prevent heparin-induced thrombocytopenia: what do we know?

Heparin-induced thrombocytopenia (HIT) is a life-threatening, immune-mediated adverse reaction to heparin anticoagulants. The inability to predict HIT represents a considerable liability associated with heparin administration. Genetic studies of HIT are challenging due to the scarcity of true HIT cases, potential for misclassification, and many environmental risk factors. Genetic studies have not consistently identified risk alleles for HIT, the production of platelet factor 4/heparin antibodies or the thromboembolic complications of HIT. Genes implicated in HIT and platelet factor 4/heparin antibody levels include FCGR2A, TDAG8, HLA-DR and others. Compelling evidence also suggests that the FCGR2A H131R polymorphism is associated with HIT-related thrombosis. There is a need for well-powered, multiethnic studies with laboratory confirmation of HIT, detailed patient- and drug-specific data, and inclusion of both serologic and thromboembolic outcomes. Genomic biomarkers identified from such studies offer the possibility of shifting current clinical practice paradigms from early detection and treatment to prevention.

Heparin-Induced Thrombocytopenia in the Critically Ill Patient

Heparin-induced thrombocytopenia (HIT) is associated with clinically significant morbidity and mortality. Patients who are critically ill are commonly thrombocytopenic and exposed to heparin. Although HIT should be considered, it is not usually the cause of thrombocytopenia in the medical-surgical ICU population. A systematic approach to the patient who is critically ill who has thrombocytopenia according to clinical features, complemented by appropriate laboratory confirmation, should lead to a reduction in inappropriate laboratory testing and reduce the use of more expensive and less reliable anticoagulants. If the patient is deemed as being at intermediate or high risk for HIT or if HIT is confirmed by means of the serotonin-release assay, heparin should be stopped, heparin-bonded catheters should be removed, and a direct antithrombin or fondaparinux should be initiated to reduce the risk of thrombosis. Warfarin is absolutely contraindicated in the acute phase of HIT; if administered, its effects must be reversed by using vitamin K.

Nonpharmacist Health Care Providers' Knowledge of and Opinions Regarding Medication Costs in Critically Ill Patients

Purpose: Medication cost is frequently overlooked when treating critically ill patients. Stewardship of health care resources in high-utilization settings is imperative. This study was conducted to determine nonpharmacist health care providers' knowledge and perceptions of medication costs in a medical intensive care unit (MICU). Methods: Nonpharmacist health care providers in a MICU completed a 27-item survey. The survey queried perceptions regarding medication cost, cost-limiting strategies, and most/least expensive medications in 8 classes, medication price ranges, and intravenous-to-oral comparisons for commonly prescribed medications. Responses were analyzed using descriptive statistics and compared between providers using Fisher exact tests. Results: Among 98 health care providers (76 medical trainees, 5 attending physicians, 17 nurses), when ordering a medication, 49% consider its cost. Few (15%) providers considered themselves knowledgeable regarding medication costs with no difference between providers (P = .174). Attending physicians were more aware of the most/least expensive medications than residents (correct out of 16: 9.6 vs 8.5, P = .044). The correct price ranges for select medications (11%-36%, P = .373) and intravenous-to-oral relative costs (3%-49%, P = .596) were similarly low. Most (59%) believed pharmacists limit expensive medication use, particularly senior physicians (58% resident vs 100% attending, P = .007). Conclusion: In spite of a goal of cost consideration, most nonpharmacist health care providers are unaware of medication costs and fail to include them in decision making. These knowledge gaps and perceptions should inform future efforts to improve knowledge and attitudes regarding medication costs.

Evaluation of a Reflex Testing Algorithm for Suspected Heparin-Induced Thrombocytopenia

OBJECTIVES

We implemented a policy of reflex serotonin-release assay (SRA) testing for all patients with a positive heparin-induced thrombocytopenia (HIT) immunoassay.

METHODS

We identified all patients who had SRA testing sent as a consequence of a positive HIT immunoassay test. We reviewed charts of patients to calculate the 4Ts clinical score, determined the effect of testing on clinical management, and documented the change in utilization of direct thrombin inhibitors (DTIs).

RESULTS

The likelihood of a positive SRA varied with the optical density (OD) of the immunoassay. The performance of the immunoglobulin G (IgG)-specific and polytypic enzyme-linked immunosorbent assay was not statistically different. Both OD and 4Ts score correlated with the likelihood of a positive SRA but demonstrated poor specificity. Discontinuation of DTIs in patients with negative SRAs resulted in decreased drug utilization.

CONCLUSIONS

The IgG-specific HIT immunoassay OD correlates with the likelihood of a positive SRA but does not achieve high specificity. The reflex testing algorithm allows for definitive classification of patients, and the cost of such a reflex testing program may be offset by decreased utilization of DTIs.

Implementation of a rapid HIT immunoassay at a university hospital - Retrospective analysis of HIT laboratory orders in patients with thrombocytopenia

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is a rare cause of thrombocytopenia and a potentially life-threatening adverse drug reaction. Clinical overdiagnosis of HIT results in costly laboratory tests and anticoagulation. Criteria and algorithms for diagnosis are established, but their translation into clinical practice is still challenging.

STUDY DESIGN AND METHODS

In a retrospective approach we studied all HIT related laboratory test requests within four years and evaluated data before (1st period, 24month) and after (2nd period, 24month) replacing particle gel immunoassay (PaGIA) and enzyme-linked immunosorbent assay (ELISA) by a chemiluminescent immunoassay (CLIA). HIT was confirmed by heparin-induced platelet activation (HIPA) test. Clinical pretest probability for HIT using an implemented simplified 4Ts score and platelet count were evaluated. Costs for laboratory tests and alternative anticoagulation were calculated.

RESULTS

In 1850 patients with suspected HIT, 2327 laboratory orders were performed. In 87.2% of these orders an intermediate/high simplified 4Ts score was found. Thrombocytopenia was present in 87.1%. After replacing PaGIA and ELISA by CLIA the number of immunological and functional laboratory tests was reduced by 38.2%. The number of positive HIT immunoassays declined from 22.6% to 6.0%, while the number of positive HIPA tests among positive immunological tests increased by 19%. Altogether, acute HIT was confirmed in 59 patients. A decline in the use of alternative anticoagulants was observed in the 2nd period.

CONCLUSION

Our study shows that in a university hospital setting HIT is well-known, but diagnosis requires a precise laboratory confirmation. Replacing PaGIA and ELISA by CLIA did not influence laboratory order behavior but results in reduced overall costs for laboratory diagnostics and alternative anticoagulation.

Apixaban for treatment of confirmed heparin-induced thrombocytopenia: a case report and review of literature

Background

Heparin-induced thrombocytopenia (HIT) is a life and limb-threatening condition caused by the binding of platelet-activating antibodies (IgG) to multimolecular platelet factor 4 (PF4)/heparin complexes because of heparin exposure. The by-product of this interaction is thrombin formation which substantially increases the risk of venous and/or arterial thromboembolism. Currently, only one anticoagulant, argatroban, is United States Food and Drug Administration-approved for management of HIT; however, this agent is expensive and can only be given by intravenous infusion. Recently, several retrospective case-series, case reports, and one prospective study suggest that direct oral anticoagulants (DOACs) are also efficacious for treating HIT. We further review the literature regarding current diagnosis and clinical management of HIT.

Case presentation

A 66-year-old male patient developed HIT beginning on day 5 post-cardiovascular surgery; the platelet count nadir on day 10 measured 16 × 10⁹/L. Both the PF4-dependent ELISA and Serotonin-release assay were strongly positive. Despite initial anticoagulation with argatroban (day 6), the patient developed symptomatic Doppler ultrasound-documented bilateral lower extremity deep vein thrombosis on day 14 post-surgery. The patient was transitioned to the DOAC, apixaban, while still thrombocytopenic (platelet count 108) and discharged to home, with platelet count recovery and no further thrombosis at 3-month follow-up.

Conclusions

We report a patient with serologically confirmed HIT who developed symptomatic bilateral lower limb deep vein thrombosis despite anticoagulation with argatroban. The patient was switched to oral apixaban and made a complete recovery. Our patient case adds to the emerging literature suggesting that DOAC therapy is safe and efficacious for management of proven HIT.

ADAMTS13 test and/or PLASMIC clinical score in management of acquired thrombotic thrombocytopenic purpura: a cost-effective analysis

BACKGROUND

The ADAMTS13 test distinguishes thrombotic thrombocytopenic purpura (TTP) from other thrombotic microangiopathies (TMAs). The PLASMIC score helps determine the pretest probability of ADAMTS13 deficiency. Due to inherent limitations of both tests, and potential adverse effects and cost of unnecessary treatments, we performed a cost-effectiveness analysis (CEA) investigating the benefits of incorporating an in-hospital ADAMTS13 test and/or PLASMIC score into our clinical practice.

STUDY DESIGN AND METHODS

A CEA model was created to compare four scenarios for patients with TMAs, utilizing either an in-house or a send-out ADAMTS13 assay with or without prior risk stratification using PLASMIC scoring. Model variables, including probabilities and costs, were gathered from the medical literature, except for the ADAMTS13 send-out and in-house tests, which were obtained from our institutional data.

RESULTS

If only the cost is considered, in-house ADAMTS13 test for patients with intermediate- to high-risk PLASMIC score is the least expensive option ($4,732/patient). If effectiveness is assessed as measured by the number of averted deaths, send-out ADAMTS13 test is the most effective. Considering the cost/effectiveness ratio, the in-house ADAMTS13 test in patients with intermediate- to high-risk PLASMIC score is the best option, followed by the in-house ADAMTS13 test without the PLASMIC score.

CONCLUSIONS

In patients with clinical presentations of TMAs, having an in-hospital ADAMTS13 test to promptly establish the diagnosis of TTP appears to be cost-effective. Utilizing the PLASMIC score further increases the cost-effectiveness of the in-house ADAMTS13 test. Our findings indicate the benefit of having a rapid and reliable in-house ADAMTS13 test, especially in the tertiary medical center.

Direct oral anticoagulants for treatment of HIT: update of Hamilton experience and literature review

Direct oral anticoagulants (DOACs) are attractive options for treatment of heparin-induced thrombocytopenia (HIT). We report our continuing experience in Hamilton, ON, Canada, since January 1, 2015 (when we completed our prospective study of rivaroxaban for HIT), using rivaroxaban for serologically confirmed HIT (4Ts score ≥4 points; positive platelet factor 4 [PF4]/heparin immunoassay, positive serotonin-release assay). We also performed a literature review of HIT treatment using DOACs (rivaroxaban, apixaban, dabigatran, edoxaban). We focused on patients who received DOAC therapy for acute HIT as either primary therapy (group A) or secondary therapy (group B; initial treatment using a non-DOAC/non-heparin anticoagulant with transition to a DOAC during HIT-associated thrombocytopenia). Our primary end point was occurrence of objectively documented thrombosis during DOAC therapy for acute HIT. We found that recovery without new, progressive, or recurrent thrombosis occurred in all 10 Hamilton patients with acute HIT treated with rivaroxaban. Data from the literature review plus these new data identified a thrombosis rate of 1 of 46 patients (2.2%; 95% CI, 0.4%-11.3%) in patients treated with rivaroxaban during acute HIT (group A, n = 25; group B, n = 21); major hemorrhage was seen in 0 of 46 patients. Similar outcomes in smaller numbers of patients were observed with apixaban (n = 12) and dabigatran (n = 11). DOACs offer simplified management of selected patients, as illustrated by a case of persisting (autoimmune) HIT (>2-month platelet recovery with inversely parallel waning of serum-induced heparin-independent serotonin release) with successful outpatient rivaroxaban management of HIT-associated thrombosis. Evidence supporting efficacy and safety of DOACs for acute HIT is increasing, with the most experience reported for rivaroxaban.

Emerging Role of Direct Oral Anticoagulants in the Management of Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) and heparin-induced thrombocytopenia with thrombosis (HITT) are rare but potentially limb- and life-threatening complications of heparin therapy. Continuation of heparin or low-molecular-weight heparin is contraindicated due to platelet activation in the presence of (heparin-dependent) HIT antibodies. Primary treatment options currently include argatroban, fondaparinux, or bivalirudin. However, the parenteral administration routes and interference of argatroban with traditional coagulation markers complicate management. The goal of this review is to assess the viability of direct oral anticoagulants as an alternative treatment option in patients with HIT/HITT. Their use in HIT/HITT is reasonable, given absent cross-reactivity preformed with HIT antibodies. Furthermore, their rapid onset of action and induction of effective anticoagulation provide a favorable basis for their use in this condition. Herein, we summarize 3 studies and 8 case reports comprising 56 patients in whom direct oral anticoagulants were used in the treatment of HIT/HITT.

HIT the price point with fondaparinux

In this issue of Blood, Aljabri and colleagues report on their analysis of the cost-effectiveness of fondaparinux for the treatment of heparin-induced thrombocytopenia (HIT) in the United States.1 HIT is a relatively uncommon but serious complication of the use of heparin-containing products.2 Treatment of HIT requires use of an alternate anticoagulant such as the direct thrombin inhibitors argatroban and bivalirudin.3