Antithrombotic Therapy for VTE Disease: Compendium and Review of CHEST Guidelines 2012-2021

The CHEST Antithrombotic Therapy for Venous Thromboembolism Disease evidence-based guidelines are now updated in a more frequent, focused manner. Guidance statements from the most recent full guidelines and two subsequent updates have not been gathered into a single source. An international panel of experts with experience in prior antithrombotic therapy guideline development reviewed the 2012 CHEST antithrombotic therapy guidelines and its two subsequent updates. All guideline statements and their associated patient, intervention, comparator, and outcome questions were assembled. A modified Delphi process was used to select statements considered relevant to current clinical care. The panel further endorsed minor phrasing changes to match the standard language for guidance statements using the modified Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) format endorsed by the CHEST Guidelines Oversight Committee. The panel appended comments after statements deemed as relevant, including suggesting that statements be updated in future guidelines because of interval evidence. We include 58 guidance statements from prior versions of the antithrombotic therapy guidelines, with updated phrasing as needed to adhere to contemporary nomenclature. Statements were classified as strong or weak recommendations based on high-certainty, moderate-certainty, and low-certainty evidence using GRADE methodology. The panel suggested that five statements are no longer relevant to current practice. As CHEST continues to update guidance statements relevant to antithrombotic therapy for VTE disease, this article serves as a unified collection of currently relevant statements from the preceding three guidelines. Suggestions have been made to update specific statements in future publications.

A machine learning approach to predict mortality due to immune-mediated thrombotic thrombocytopenic purpura

Background

Mortality due to immune-mediated thrombotic thrombocytopenic purpura (iTTP) remains significant. Predicting mortality risk may potentially help individualize treatment. The French Thrombotic Microangiopathy (TMA) Reference Score has not been externally validated in the United States. Recent advances in machine learning technology can help analyze large numbers of variables with complex interactions for the development of prediction models.

Objectives

To validate the French TMA Reference Score in the United States Thrombotic Microangiopathy (USTMA) iTTP database and subsequently develop a novel mortality prediction tool, the USTMA TTP Mortality Index.

Methods

We analyzed variables available at the time of initial presentation, including demographics, symptoms, and laboratory findings. We developed our model using gradient boosting machine, a machine learning ensemble method based on classification trees, implemented in the R package gbm.

Results

In our cohort (n = 419), the French score predicted mortality with an area under the receiver operating characteristic curve of 0.63 (95% CI: 0.50-0.77), sensitivity of 0.35, and specificity of 0.84. Our gradient boosting machine model selected 8 variables to predict acute mortality with a cross-validated area under the receiver operating characteristic curve of 0.77 (95% CI: 0.71-0.82). The 2 cutoffs corresponded to sensitivities of 0.64 and 0.50 and specificities of 0.76 and 0.87, respectively.

Conclusion

The USTMA Mortality Index was acceptable for predicting mortality due to acute iTTP in the USTMA registry, but not sensitive enough to rule out death. Identifying patients at high risk of iTTP-related mortality may help individualize care and ultimately improve iTTP survival outcomes. Further studies are needed to provide external validation. Our model is one of many recent examples where machine learning models may show promise in clinical prediction tools in healthcare.

Primary Care Clinicians' Prescribing Patterns of Reduced-Dose Direct Oral Anticoagulants for Extended-Phase Venous Thromboembolism Treatment

The direct anticoagulants (DOACs), apixaban and rivaroxaban, are used for extended-phase treatment of venous thromboembolism (VTE) and have labeling for dose reduction for this indication. The objective of this study was to better understand primary care clinician prescribing patterns of apixaban and rivaroxaban for extended-phase anticoagulation. We conducted a 21-question survey targeting members of the American College of Physicians and United States Veterans Administration anticoagulation management services. Survey questions covered prescribing behaviors for dose reduction of apixaban and rivaroxaban for extended VTE treatment, as well as questions related to the respondent's practice setting. We used logistic regression to assess associations between demographics and prescribing behaviors. We used k-means clustering to identify distinct groups of prescribing patterns. Among 227 respondents, most were attending physicians (60%) and one-third (34%) practiced in internal medicine or primary care. Most (59%) indicated they dose-reduced DOACs. Hospitalists (no outpatient care) were least likely to dose-reduce (OR 0.09 [95% CI 0.03-0.22]), as well as early-career clinicians (0.53 [0.30-0.91]). Pharmacists and clinicians who treat over 500 VTE patients annually were most likely to dose reduce (6.4 [2.9-16.3]), (2.9 [1.5-6.0]), respectively. We identified five clusters of dosing behaviors and characterized clinician makeup. Clusters were primarily differentiated by frequency of dose reduction, DOAC preference, and temporary re-escalation of doses. We identified clinician characteristics that are associated with dose-reduction prescribing behaviors; these analyses provide insight into where targeted interventions, such as protocolization and education, would be most beneficial.

American Society of Hematology 2023 guidelines for management of venous thromboembolism: thrombophilia testing

Hereditary and acquired thrombophilia are risk factors for venous thromboembolism (VTE). Whether testing helps guide management decisions is controversial. These evidence-based guidelines from the American Society of Hematology (ASH) intend to support decision making about thrombophilia testing. ASH formed a multidisciplinary guideline panel covering clinical and methodological expertise and minimizing bias from conflicts of interest. The McMaster University GRADE Centre provided logistical support, performed systematic reviews, and created evidence profiles and evidence-to-decision tables. The Grading of Recommendations Assessment, Development, and Evaluation approach (GRADE) was used. Recommendations were subject to public comment. The panel agreed on 23 recommendations regarding thrombophilia testing and associated management. Nearly all recommendations are based on very low certainty in the evidence due to modeling assumptions. The panel issued a strong recommendation against testing the general population before starting combined oral contraceptives (COCs) and conditional recommendations for thrombophilia testing in the following scenarios: (a) patients with VTE associated with nonsurgical major transient or hormonal risk factors; (b) patients with cerebral or splanchnic venous thrombosis, in settings where anticoagulation would otherwise be discontinued; (c) individuals with a family history of antithrombin, protein C, or protein S deficiency when considering thromboprophylaxis for minor provoking risk factors and for guidance to avoid COCs/hormone replacement therapy; (d) pregnant women with a family history of high-risk thrombophilia types; and (e) patients with cancer at low or intermediate risk of thrombosis and with a family history of VTE. For all other questions, the panel provided conditional recommendations against testing for thrombophilia.

Comparison of Venous Thromboembolism Outcomes after COVID-19 and Influenza Vaccinations

Background  Published data on the risk of venous thromboembolism (VTE) with coronavirus disease 2019 (COVID-19) vaccines are scarce and inconclusive, leading to an unmet need for further studies. Methods  A retrospective, multicentered study of adult patients vaccinated for one of the three approved COVID-19 vaccines in the United States of America and a pre-COVID-19 cohort of patients vaccinated for influenza at two institutions: Mayo Clinic Enterprise sites and the Medical College of Wisconsin, looking at rate of VTE over 90 days. VTE was identified by applying validated natural language processing algorithms to relevant imaging studies. Kaplan-Meier curves were used to evaluate rate of VTE and Cox proportional hazard models for incident VTE after vaccinations. Sensitivity analyses were performed for age, sex, outpatient versus inpatient status, and type of COVID-19 vaccine. Results  A total of 911,381 study subjects received COVID-19 vaccine (mean age: 56.8 [standard deviation, SD: 18.3] years, 55.3% females) and 442,612 received influenza vaccine (mean age: 56.5 [SD: 18.3] years, 58.7% females). VTE occurred within 90 days in 1,498 (0.11%) of the total 1,353,993 vaccinations: 882 (0.10%) in the COVID-19 and 616 (0.14%) in the influenza vaccination cohort. After adjusting for confounding variables, there was no difference in VTE event rate after COVID-19 vaccination compared with influenza vaccination (adjusted hazard ratio: 0.95 [95% confidence interval: 0.85-1.05]). No significant difference in VTE rates was observed between the two cohorts on sensitivity analyses. Conclusion  In this large cohort of COVID-19-vaccinated patients, risk of VTE at 90 days was low and no different than a pre-COVID-19 cohort of influenza-vaccinated patients.

Effect of the P-Selectin Inhibitor Crizanlizumab on Survival Free of Organ Support in Patients Hospitalized for COVID-19: A Randomized Controlled Trial

BACKGROUND

COVID-19 has been associated with endothelial injury, resultant microvascular inflammation and thrombosis. Activated endothelial cells release and express P-selectin and von Willebrand factor, both of which are elevated in severe COVID-19 and may be implicated in the disease pathophysiology. We hypothesized that crizanlizumab, a humanized monoclonal antibody to P-selectin, would reduce morbidity and death in patients hospitalized for COVID-19.

METHODS

An international, adaptive, randomized controlled platform trial, funded by the National Heart, Lung, and Blood Institute, randomly assigned 422 patients hospitalized with COVID-19 with moderate or severe illness to receive either a single infusion of the P-selectin inhibitor crizanlizumab (at a dose of 5 mg/kg) plus standard of care or standard of care alone in an open-label 1:1 ratio. The primary outcome was organ support-free days, evaluated on an ordinal scale consisting of the number of days alive free of organ support through the first 21 days after trial entry.

RESULTS

The study was stopped for futility by the data safety monitoring committee. Among 421 randomized patients with known 21-day outcomes, 163 patients (77%) randomized to the crizanlizumab plus standard-of-care arm did not require any respiratory or cardiovascular organ support compared with 169 (80%) in the standard-of-care-alone arm. The adjusted odds ratio for the effect of crizanlizumab on organ support-free days was 0.70 (95% CI, 0.43-1.16), where an odds ratio >1 indicates treatment benefit, yielding a posterior probability of futility (odds ratio <1.2) of 98% and a posterior probability of inferiority (odds ratio <1.0) of 91%. Overall, there were 37 deaths (17.5%) in the crizanlizumab arm and 27 deaths (12.8%) in the standard-of-care arm (hazard ratio, 1.33 [95% CrI, 0.85-2.21]; [probability of hazard ratio>1] = 0.879).

CONCLUSIONS

Crizanlizumab, a P-selectin inhibitor, did not result in improvement in organ support-free days in patients hospitalized with COVID-19.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04505774.

Plasma tissue-type plasminogen activator is associated with lipoprotein(a) and clinical outcomes in hospitalized patients with COVID-19

Background

Patients with COVID-19 have a higher risk of thrombosis and thromboembolism, but the underlying mechanism(s) remain to be fully elucidated. In patients with COVID-19, high lipoprotein(a) (Lp(a)) is positively associated with the risk of ischemic heart disease. Lp(a), composed of an apoB-containing particle and apolipoprotein(a) (apo(a)), inhibits the key fibrinolytic enzyme, tissue-type plasminogen activator (tPA). However, whether the higher Lp(a) associates with lower tPA activity, the longitudinal changes of these parameters in hospitalized patients with COVID-19, and their correlation with clinical outcomes are unknown.

Objectives

To assess if Lp(a) associates with lower tPA activity in COVID-19 patients, and how in COVID-19 populations Lp(a) and tPA change post infection.

Methods

Endogenous tPA enzymatic activity, tPA or Lp(a) concentration were measured in plasma from hospitalized patients with and without COVID-19. The association between plasma tPA and adverse clinical outcomes was assessed.

Results

In hospitalized patients with COVID-19, we found lower tPA enzymatic activity and higher plasma Lp(a) than that in non-COVID-19 controls. During hospitalization, Lp(a) increased and tPA activity decreased, which associates with mortality. Among those who survived, Lp(a) decreased and tPA enzymatic activity increased during recovery. In patients with COVID-19, tPA activity is inversely correlated with tPA concentrations, thus, in another larger COVID-19 cohort, we utilized plasma tPA concentration as a surrogate to inversely reflect tPA activity. The tPA concentration was positively associated with death, disease severity, plasma inflammatory, and prothrombotic markers, and with length of hospitalization among those who were discharged.

Conclusion

High Lp(a) concentration provides a possible explanation for low endogenous tPA enzymatic activity, and poor clinical outcomes in patients with COVID-19.

Associations between ABO non-identical platelet transfusions and patient outcomes-A multicenter retrospective analysis

BACKGROUND

Due to platelet availability limitations, platelet units ABO mismatched to recipients are often transfused. However, since platelets express ABO antigens and are collected in plasma which may contain ABO isohemagglutinins, it remains controversial as to whether ABO non-identical platelet transfusions could potentially pose harm and/or have reduced efficacy.

STUDY DESIGN AND METHODS

The large 4-year publicly available Recipient Epidemiology and Donor Evaluation Study-III (REDS-III) database was used to investigate patient outcomes associated with ABO non-identical platelet transfusions. Outcomes included mortality, sepsis, and subsequent platelet transfusion requirements.

RESULTS

Following adjustment for possible confounding factors, no statistically significant association between ABO non-identical platelet transfusion and increased risk of mortality was observed in the overall cohort of 21,176 recipients. However, when analyzed by diagnostic category and recipient ABO group, associations with increased mortality for major mismatched transfusions were noted in two of eight subpopulations. Hematology/Oncology blood group A and B recipients (but not group O) showed a Hazard Ratio (HR) of 1.29 (95%CI: 1.03-1.62) and intracerebral hemorrhage group O recipients (but not groups A and B) showed a HR of 1.75 (95%CI: 1.10-2.80). Major mismatched transfusions were associated with increased odds of receiving additional platelet transfusion each post-transfusion day (through day 5) regardless of the recipient blood group.

DISCUSSION

We suggest that prospective studies are needed to determine if specific patient populations would benefit from receiving ABO identical platelet units. Our findings indicate that ABO-identical platelet products minimize patient exposure to additional platelet doses.

DOAC compared with warfarin for VTE in patients with obesity: a retrospective cohort study conducted through the VENUS network

The effectiveness and safety of direct oral anticoagulants (DOAC) compared with warfarin remains uncertain in obese patients. We assessed the comparative effectiveness and safety of DOACs with warfarin for the treatment of VTE among obese patients. This multi-center retrospective cohort study included adults with a BMI ≥ 35 kg/m2 or weight ≥ 120 kg prescribed either DOAC (apixaban, dabigatran, edoxaban, rivaroxaban) or warfarin for a VTE diagnosis. The primary outcome was the 12-month rate of recurrent VTE. The secondary outcome was the 12-month rate of major bleeding. Among 5626 patients, 67% were prescribed warfarin and 33% were prescribed a DOAC. The 12-month VTE recurrence rate was 3.6% (67/1823) for patients treated with DOAC compared with 3.8% (143/3664) for patients treated with warfarin [odds ratio for recurrent VTE on warfarin versus DOAC (OR) (95% CI).07 (0.80, 1.45)]. The 12-month major bleeding rate was 0.5% (10/1868) for patients on DOAC versus 2.4% (89/3758) on warfarin [OR 4.25 (2.19, 8.22)]. Similar proportions of recurrent VTE occurred across BMI thresholds on DOAC and warfarin: for BMI ≥ 35 kg/m2 (N = 5412), 3.6% versus 3.8%, respectively [OR 1.08 (0.80, 1.46)]; for BMI ≥ 40 kg/m2 (N = 2321), 4.4% versus 3.5%, respectively [OR 0.80 (0.51, 1.26)]; and for BMI ≥ 50 kg/m2 (N = 560), 3.1% versus 3.7%, respectively [OR 1.18 (0.39, 3.56)]. Similar proportions of recurrent VTE occurred in patients with obesity treated for VTE with DOACs and warfarin. DOACs were associated with lower major bleeding compared to warfarin in patients with obesity and VTE.

Effect of P2Y12 Inhibitors on Organ Support-Free Survival in Critically Ill Patients Hospitalized for COVID-19: A Randomized Clinical Trial

Importance

Platelet activation is a potential therapeutic target in patients with COVID-19.

Objective

To evaluate the effect of P2Y12 inhibition among critically ill patients hospitalized for COVID-19.

Design, Setting, and Participants

This international, open-label, adaptive platform, 1:1 randomized clinical trial included critically ill (requiring intensive care-level support) patients hospitalized with COVID-19. Patients were enrolled between February 26, 2021, through June 22, 2022. Enrollment was discontinued on June 22, 2022, by the trial leadership in coordination with the study sponsor given a marked slowing of the enrollment rate of critically ill patients.

Intervention

Participants were randomly assigned to receive a P2Y12 inhibitor or no P2Y12 inhibitor (usual care) for 14 days or until hospital discharge, whichever was sooner. Ticagrelor was the preferred P2Y12 inhibitor.

Main Outcomes and Measures

The primary outcome was organ support-free days, evaluated on an ordinal scale that combined in-hospital death and, for participants who survived to hospital discharge, the number of days free of cardiovascular or respiratory organ support up to day 21 of the index hospitalization. The primary safety outcome was major bleeding, as defined by the International Society on Thrombosis and Hemostasis.

Results

At the time of trial termination, 949 participants (median [IQR] age, 56 [46-65] years; 603 male [63.5%]) had been randomly assigned, 479 to the P2Y12 inhibitor group and 470 to usual care. In the P2Y12 inhibitor group, ticagrelor was used in 372 participants (78.8%) and clopidogrel in 100 participants (21.2%). The estimated adjusted odds ratio (AOR) for the effect of P2Y12 inhibitor on organ support-free days was 1.07 (95% credible interval, 0.85-1.33). The posterior probability of superiority (defined as an OR > 1.0) was 72.9%. Overall, 354 participants (74.5%) in the P2Y12 inhibitor group and 339 participants (72.4%) in the usual care group survived to hospital discharge (median AOR, 1.15; 95% credible interval, 0.84-1.55; posterior probability of superiority, 80.8%). Major bleeding occurred in 13 participants (2.7%) in the P2Y12 inhibitor group and 13 (2.8%) in the usual care group. The estimated mortality rate at 90 days for the P2Y12 inhibitor group was 25.5% and for the usual care group was 27.0% (adjusted hazard ratio, 0.96; 95% CI, 0.76-1.23; P = .77).

Conclusions and Relevance

In this randomized clinical trial of critically ill participants hospitalized for COVID-19, treatment with a P2Y12 inhibitor did not improve the number of days alive and free of cardiovascular or respiratory organ support. The use of the P2Y12 inhibitor did not increase major bleeding compared with usual care. These data do not support routine use of a P2Y12 inhibitor in critically ill patients hospitalized for COVID-19.

Trial Registration

ClinicalTrials.gov Identifier: NCT04505774.

Effect of Thromboprophylaxis on Clinical Outcomes After COVID-19 Hospitalization

BACKGROUND

Patients hospitalized with COVID-19 have an increased incidence of thromboembolism. The role of extended thromboprophylaxis after hospital discharge is unclear.

OBJECTIVE

To determine whether anticoagulation is superior to placebo in reducing death and thromboembolic complications among patients discharged after COVID-19 hospitalization.

DESIGN

Prospective, randomized, double-blind, placebo-controlled clinical trial. (ClinicalTrials.gov: NCT04650087).

SETTING

Done during 2021 to 2022 among 127 U.S. hospitals.

PARTICIPANTS

Adults aged 18 years or older hospitalized with COVID-19 for 48 hours or more and ready for discharge, excluding those with a requirement for, or contraindication to, anticoagulation.

INTERVENTION

2.5 mg of apixaban versus placebo twice daily for 30 days.

MEASUREMENTS

The primary efficacy end point was a 30-day composite of death, arterial thromboembolism, and venous thromboembolism. The primary safety end points were 30-day major bleeding and clinically relevant nonmajor bleeding.

RESULTS

Enrollment was terminated early, after 1217 participants were randomly assigned, because of a lower than anticipated event rate and a declining rate of COVID-19 hospitalizations. Median age was 54 years, 50.4% were women, 26.5% were Black, and 16.7% were Hispanic; 30.7% had a World Health Organization severity score of 5 or greater, and 11.0% had an International Medical Prevention Registry on Venous Thromboembolism risk prediction score of greater than 4. Incidence of the primary end point was 2.13% (95% CI, 1.14 to 3.62) in the apixaban group and 2.31% (CI, 1.27 to 3.84) in the placebo group. Major bleeding occurred in 2 (0.4%) and 1 (0.2%) and clinically relevant nonmajor bleeding occurred in 3 (0.6%) and 6 (1.1%) apixaban-treated and placebo-treated participants, respectively. By day 30, thirty-six (3.0%) participants were lost to follow-up, and 8.5% of apixaban and 11.9% of placebo participants permanently discontinued the study drug treatment.

LIMITATIONS

The introduction of SARS-CoV-2 vaccines decreased the risk for hospitalization and death. Study enrollment spanned the peaks of the Delta and Omicron variants in the United States, which influenced illness severity.

CONCLUSION

The incidence of death or thromboembolism was low in this cohort of patients discharged after hospitalization with COVID-19. Because of early enrollment termination, the results were imprecise and the study was inconclusive.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Race, rituximab, and relapse in TTP

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is characterized by recurring episodes of thrombotic microangiopathy, causing ischemic organ impairment. Black patients are overrepresented in iTTP cohorts in the United States, but racial disparities in iTTP outcome and response to therapy have not been studied. Using the United States Thrombotic Microangiopathies Consortium iTTP Registry, we evaluated the impact of race on mortality and relapse-free survival (RFS) in confirmed iTTP in the United States from 1995 to 2020. We separately examined the impact of rituximab therapy and presentation with newly diagnosed (de novo) or relapsed iTTP on RFS by race. A total of 645 participants with 1308 iTTP episodes were available for analysis. Acute iTTP mortality did not differ by race. When all episodes of iTTP were included, Black race was associated with shorter RFS (hazard ratio [HR], 1.60; 95% CI, 1.16-2.21); the addition of rituximab to corticosteroids improved RFS in White (HR, 0.37; 95% CI, 0.18-0.73) but not Black patients (HR, 0.96; 95% CI, 0.71-1.31). In de novo iTTP, rituximab delayed relapse, but Black patients had shorter RFS than White patients, regardless of treatment. In relapsed iTTP, rituximab significantly improved RFS in White but not Black patients. Race affects overall relapse risk and response to rituximab in iTTP. Black patients may require closer monitoring, earlier retreatment, and alternative immunosuppression after rituximab treatment. How race, racism, and social determinants of health contribute to the disparity in relapse risk in iTTP deserves further study.

Physician perceptions and use of reduced‐dose direct oral anticoagulants for extended phase venous thromboembolism treatment

Background

The direct oral anticoagulants (DOACs), apixaban and rivaroxaban, have been studied for extended‐phase treatment of venous thromboembolism (VTE). Yet, scant evidence exists surrounding clinician practice and decision‐making regarding dose reduction.

Aims

Report clinician practice and characteristics surrounding dose reduction of DOACs for extended‐phase VTE treatment.

Methods

We conducted a 16‐question REDCap survey between July 14, 2021, and September 13, 2021, among ISTH 2021 Congress attendees and on Twitter. We explored factors associated with dose reduction using logistic regression. We used k‐means clustering to identify distinct groups of dose‐reduction decision‐making. Random forest analysis explored demographics with respect to identified groups.

Results

Among 171 respondents, most were attending academic physicians from North America. Clinicians who treated larger volumes of patients had higher odds of dose reduction. We identified five clusters that showed distinct patterns of behavior regarding dose reduction. Cluster 1 rarely dose reduces and likely prescribes rivaroxaban over apixaban; cluster 2 dose reduces frequently, does not consider age when dose‐reducing, is least likely to temporarily reescalate dosing, and prescribes apixaban and rivaroxaban equally; cluster 3 dose reduces <50% of the time, and temporarily reescalates dosing during increased VTE risk; cluster 4 dose reduces frequently, temporarily reescalates dosing, and is most likely to prescribe apixaban over rivaroxaban; and cluster 5 dose reduces most frequently, and takes the fewest risk factors into consideration when deciding to dose reduce.

Conclusions

Most clinicians elect to dose‐reduce DOACs for extended‐phase anticoagulation. The likelihood of a clinician to dose reduce increases with volume of patients treated. Clinician prescribing patterns cluster around VTE risk factors as well as reescalation during high‐risk periods.

Management of cancer-associated thrombosis with thrombocytopenia: Impact of the ISTH guidance statement

Background

Optimal management of cancer-associated thrombosis (CAT) in patients with thrombocytopenia remains difficult given competing risks of recurrent thrombosis and increased bleeding. We determine the impact of the ISTH Scientific and Standardization Committee (SCC) guidance on CAT management and thrombocytopenia on platelet transfusion, bleeding, and recurrent thrombosis.

Methods

A retrospective review was performed of patients with CAT and thrombocytopenia who required anticoagulation for VTE for 11 months before and after implementation of the ISTH SCC guidance. Medical records were reviewed to identify the type of VTE event, number of platelet transfusions, incidence of bleeding, and VTE recurrence within pre- and postintervention time periods.

Results

A total of 41 and 80 cases were included in the preintervention and postintervention periods, respectively. The preintervention group showed a trend toward less acute VTE events (39% vs 55%; P = .05). The postintervention period had an increased per-patient platelet transfusion (median, 2.5 vs 4; P = .05). Nonmajor bleeding was increased in the postintervention group (2% vs 16%; P = 0.03) and included all six (8%) major hemorrhages (P = .09). There was numerically less recurrent thrombosis in the postintervention group (20% vs 8%; P = .07), which was not significantly different when accounting for acuity of VTE. Management adherence was strong, at 91%, in the postintervention group.

Conclusion

The ISTH guidance on management of cancer-associated thrombosis in patients with thrombocytopenia was successfully implemented in an academic medical center. There was no significant difference in bleeding or recurrent thrombosis outcomes after adjusting for acuity of VTE.

The Recipient Epidemiology and Donor Evaluation Study-IV-Pediatric (REDS-IV-P): A research program striving to improve blood donor safety and optimize transfusion outcomes across the lifespan

BACKGROUND

The Recipient Epidemiology and Donor Evaluation Study-IV-Pediatric (REDS-IV-P) is a new iteration of prior National Heart, Lung, and Blood Institute (NHLBI) REDS programs that focus on improving transfusion recipient outcomes across the lifespan as well as the safety and availability of the blood supply.

STUDY DESIGN AND METHODS

The US program includes blood centers and hospitals (22 including 6 free-standing Children's hospitals) in four geographic regions. The Brazilian program has 5 participating hemocenters. A Center for Transfusion Laboratory Studies (CTLS) and a Data Coordinating Center (DCC) support synergistic studies and activities over the 7-year REDS-IV-P program.

RESULTS

The US is building a centralized, vein-to-vein (V2V) database, linking information collected from blood donors, their donations, the resulting manufactured components, and data extracts from hospital electronic medical records of transfused and non-transfused patients. Simultaneously, the Brazilian program is building a donor, donation, and component database. The databases will serve as the backbone for retrospective and prospective observational studies in transfusion epidemiology, transfusion recipient outcomes, blood component quality, and emerging blood safety issues. Special focus will be on preterm infants, patients with sickle cell disease, thalassemia or cancer, and the effect of donor biologic variability and component manufacturing on recipient outcomes. A rapid response capability to emerging safety threats has resulted in timely studies related to Severe Acute Respiratory Syndrome Corona Virus-2 (SARS-CoV-2).

CONCLUSIONS

The REDS-IV-P program endeavors to improve donor-recipient-linked research with a focus on children and special populations while also maintaining the flexibility to address emerging blood safety issues.

Catheter Based System for the Treatment of Left Ventricular Assist Device Thrombosis

BACKGROUND

Thrombotic complications continue to pose challenges to patients on Left Ventricular Assist Device (LVAD) support. The Hoplon system was developed to administer catheter based lytic therapy with a novel approach to embolic protection.

METHODS

Two porcine non-survival surgeries were performed in which off pump LVAD insertion was followed by injection of thrombus into the impeller, isolation of the pump using the Hoplon system, and administration of lytic therapy to the pump chamber. Successful thrombus resolution was confirmed by pathological examination of the LVAD and brain tissue after animal sacrifice.

RESULTS

Limitations of the prototype design resulted in extrusion of thrombus from around the catheter in the first animal. Subsequent device modifications resulted in resolution of LVAD thrombus as confirmed on removal and examination of the pump. Pathological examination of the brain tissue revealed the absence of any embolic or hemorrhagic complications.

CONCLUSIONS

Early animal studies suggest feasibility in restoring function to an LVAD while at the same time preventing cerebroembolic events using the Hoplon system.

Effect of P2Y12 Inhibitors on Survival Free of Organ Support Among Non-Critically Ill Hospitalized Patients With COVID-19: A Randomized Clinical Trial

Importance

Platelets represent a potential therapeutic target for improved clinical outcomes in patients with COVID-19.

Objective

To evaluate the benefits and risks of adding a P2Y12 inhibitor to anticoagulant therapy among non-critically ill patients hospitalized for COVID-19.

Design, Setting, and Participants

An open-label, bayesian, adaptive randomized clinical trial including 562 non-critically ill patients hospitalized for COVID-19 was conducted between February 2021 and June 2021 at 60 hospitals in Brazil, Italy, Spain, and the US. The date of final 90-day follow-up was September 15, 2021.

Interventions

Patients were randomized to a therapeutic dose of heparin plus a P2Y12 inhibitor (n = 293) or a therapeutic dose of heparin only (usual care) (n = 269) in a 1:1 ratio for 14 days or until hospital discharge, whichever was sooner. Ticagrelor was the preferred P2Y12 inhibitor.

Main Outcomes and Measures

The composite primary outcome was organ support-free days evaluated on an ordinal scale that combined in-hospital death (assigned a value of -1) and, for those who survived to hospital discharge, the number of days free of respiratory or cardiovascular organ support up to day 21 of the index hospitalization (range, -1 to 21 days; higher scores indicate less organ support and better outcomes). The primary safety outcome was major bleeding by 28 days as defined by the International Society on Thrombosis and Hemostasis.

Results

Enrollment of non-critically ill patients was discontinued when the prespecified criterion for futility was met. All 562 patients who were randomized (mean age, 52.7 [SD, 13.5] years; 41.5% women) completed the trial and 87% received a therapeutic dose of heparin by the end of study day 1. In the P2Y12 inhibitor group, ticagrelor was used in 63% of patients and clopidogrel in 37%. The median number of organ support-free days was 21 days (IQR, 20-21 days) among patients in the P2Y12 inhibitor group and was 21 days (IQR, 21-21 days) in the usual care group (adjusted odds ratio, 0.83 [95% credible interval, 0.55-1.25]; posterior probability of futility [defined as an odds ratio <1.2], 96%). Major bleeding occurred in 6 patients (2.0%) in the P2Y12 inhibitor group and in 2 patients (0.7%) in the usual care group (adjusted odds ratio, 3.31 [95% CI, 0.64-17.2]; P = .15).

Conclusions and Relevance

Among non-critically ill patients hospitalized for COVID-19, the use of a P2Y12 inhibitor in addition to a therapeutic dose of heparin, compared with a therapeutic dose of heparin only, did not result in an increased odds of improvement in organ support-free days within 21 days during hospitalization.

Trial Registration

ClinicalTrials.gov Identifier: NCT04505774.

Symptomatic pulmonary embolus after catheter removal in children with catheter related thrombosis: A report from the CHAT Consortium

BACKGROUND

Appropriate timing of central venous catheter (CVC) removal, in relation to start of anticoagulation, in children after the diagnosis of a CVC-related thrombosis (CRT) is not well established.

OBJECTIVES

This retrospective cohort study evaluated the incidence of symptomatic pulmonary embolism (PE) after CVC removal using data from the multi-institutional Children's Hospital-Acquired Thrombosis (CHAT) Consortium Registry.

PATIENTS/METHODS

The CHAT Registry consists of data from children aged 0-21 years with a hospital-acquired venous thromboembolism. Eligible subjects were those with CRT diagnosed <3 days after CVC removal. Subjects were excluded if the CRT was due to a failed CVC insertion. Subjects were divided into three groups: those with CVC removal without anticoagulation, those with CVC removal <48 h after starting anticoagulation, and those with CVC removal ≥48 h after starting anticoagulation.

RESULTS

A total of 687 CRT events from 663 subjects were included. A majority of CRT events were in subjects with peripherally inserted central catheters (62.3%, n = 428). For the 611 CRT events in which the CVC was removed, there was only one case of symptomatic PE (0.16%), which occurred <48 h after initiation of anticoagulation.

CONCLUSIONS

While current guidelines suggest anticoagulation before CVC removal in the setting of a CRT to prevent embolization, CVC removal is not associated with symptomatic PE regardless of duration of anticoagulation before CVC removal.

Thrombo-inflammatory biomarkers and D-dimer in a biracial cohort study

BACKGROUND

Higher D-dimer is a risk factor for cardiovascular diseases and venous thromboembolism. In the general population, D-dimer and other thrombo-inflammatory biomarkers are higher among Black individuals, who also have higher risk of these conditions compared to White people.

OBJECTIVE

To assess whether Black individuals have an exaggerated correlation between D-dimer and thrombo-inflammatory biomarkers characteristic of cardiovascular diseases.

METHODS

Linear regression was used to assess correlations of 11 thrombo-inflammatory biomarkers with D-dimer in a cross-sectional study of 1068 participants of the biracial Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort.

RESULTS

Adverse levels of most biomarkers, especially fibrinogen, factor VIII, C-reactive protein, N-terminal pro-B-type natriuretic peptide, and interleukin (IL)-6, were associated with higher D-dimer. Several associations with D-dimer differed significantly by race. For example, the association of factor VIII with D-dimer was more than twice as large in Black compared to White participants. Specifically, D-dimer was 26% higher per standard deviation (SD) higher factor VIII in Black adults and was only 11% higher per SD higher factor VIII in White adults. In Black but not White adults, higher IL-10 and soluble CD14 were associated with higher D-dimer.

CONCLUSIONS

Findings suggest that D-dimer might relate to Black/White differences in cardiovascular diseases and venous thromboembolism because it is a marker of amplified thrombo-inflammatory response in Black people. Better understanding of contributors to higher D-dimer in the general population is needed.

Randomized trials of therapeutic heparin for COVID-19: A meta-analysis

BACKGROUND

Pulmonary endothelial injury and microcirculatory thromboses likely contribute to hypoxemic respiratory failure, the most common cause of death, in patients with COVID-19. Randomized controlled trials (RCTs) suggest differences in the effect of therapeutic heparin between moderately and severely ill patients with COVID-19. We did a systematic review and meta-analysis of RCTs to determine the effects of therapeutic heparin in hospitalized patients with COVID-19.

METHODS

We searched PubMed, Embase, Web of Science, medRxiv, and medical conference proceedings for RCTs comparing therapeutic heparin with usual care, excluding trials that used oral anticoagulation or intermediate doses of heparin in the experimental arm. Mantel-Haenszel fixed-effect meta-analysis was used to combine odds ratios (ORs).

RESULTS AND CONCLUSIONS

There were 3 RCTs that compared therapeutic heparin to lower doses of heparin in 2854 moderately ill ward patients, and 3 RCTs in 1191 severely ill patients receiving critical care. In moderately ill patients, there was a nonsignificant reduction in all-cause death (OR, 0.76; 95% CI, 0.57-1.02), but significant reductions in the composite of death or invasive mechanical ventilation (OR, 0.77; 95% CI, 0.60 0.98), and death or any thrombotic event (OR, 0.58; 95% CI, 0.45-0.77). Organ support-free days alive (OR, 1.29; 95% CI, 1.07-1.57) were significantly increased with therapeutic heparin. There was a nonsignificant increase in major bleeding. In severely ill patients, there was no evidence for benefit of therapeutic heparin, with significant treatment-by-subgroup interactions with illness severity for all-cause death (P = .034). In conclusion, therapeutic heparin is beneficial in moderately ill patients but not in severely ill patients hospitalized with COVID-19.

Effectiveness of therapeutic heparin versus prophylactic heparin on death, mechanical ventilation, or intensive care unit admission in moderately ill patients with covid-19 admitted to hospital: RAPID randomised clinical trial

OBJECTIVE

To evaluate the effects of therapeutic heparin compared with prophylactic heparin among moderately ill patients with covid-19 admitted to hospital wards.

DESIGN

Randomised controlled, adaptive, open label clinical trial.

SETTING

28 hospitals in Brazil, Canada, Ireland, Saudi Arabia, United Arab Emirates, and US.

PARTICIPANTS

465 adults admitted to hospital wards with covid-19 and increased D-dimer levels were recruited between 29 May 2020 and 12 April 2021 and were randomly assigned to therapeutic dose heparin (n=228) or prophylactic dose heparin (n=237).

INTERVENTIONS

Therapeutic dose or prophylactic dose heparin (low molecular weight or unfractionated heparin), to be continued until hospital discharge, day 28, or death.

MAIN OUTCOME MEASURES

The primary outcome was a composite of death, invasive mechanical ventilation, non-invasive mechanical ventilation, or admission to an intensive care unit, assessed up to 28 days. The secondary outcomes included all cause death, the composite of all cause death or any mechanical ventilation, and venous thromboembolism. Safety outcomes included major bleeding. Outcomes were blindly adjudicated.

RESULTS

The mean age of participants was 60 years; 264 (56.8%) were men and the mean body mass index was 30.3 kg/m². At 28 days, the primary composite outcome had occurred in 37/228 patients (16.2%) assigned to therapeutic heparin and 52/237 (21.9%) assigned to prophylactic heparin (odds ratio 0.69, 95% confidence interval 0.43 to 1.10; P=0.12). Deaths occurred in four patients (1.8%) assigned to therapeutic heparin and 18 patients (7.6%) assigned to prophylactic heparin (0.22, 0.07 to 0.65; P=0.006). The composite of all cause death or any mechanical ventilation occurred in 23 patients (10.1%) assigned to therapeutic heparin and 38 (16.0%) assigned to prophylactic heparin (0.59, 0.34 to 1.02; P=0.06). Venous thromboembolism occurred in two patients (0.9%) assigned to therapeutic heparin and six (2.5%) assigned to prophylactic heparin (0.34, 0.07 to 1.71; P=0.19). Major bleeding occurred in two patients (0.9%) assigned to therapeutic heparin and four (1.7%) assigned to prophylactic heparin (0.52, 0.09 to 2.85; P=0.69).

CONCLUSIONS

In moderately ill patients with covid-19 and increased D-dimer levels admitted to hospital wards, therapeutic heparin was not significantly associated with a reduction in the primary outcome but the odds of death at 28 days was decreased. The risk of major bleeding appeared low in this trial.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04362085.

Hypertriglyceridemia during hospitalization independently associates with mortality in patients with COVID-19

BACKGROUND

Alteration in blood triglyceride levels have been found in patients with coronavirus disease 2019 (COVID-19). However, the association between hypertriglyceridemia and mortality in COVID-19 patients is unknown.

OBJECTIVE

To investigate the association between alteration in triglyceride level and mortality in hospitalized COVID-19 patients.

METHODS

We conducted a retrospective study of 600 hospitalized patients with COVID-19 diagnosis (ICD10CM:U07.1) and/or SARS-CoV-2 positive testing results between March 1, 2020 and December 21, 2020 at a tertiary academic medical center in Milwaukee, Wisconsin. De-identified data, including demographics, medical history, and blood triglyceride levels were collected and analyzed. Of the 600 patients, 109 patients died. The triglyceride value on admission was considered the baseline and the peak was defined as the highest level reported during the entire period of hospitalization. Hypertriglyceridemia was defined as greater than 150 mg/dl. Logistic regression analyses were performed to evaluate the association between hypertriglyceridemia and mortality.

RESULTS

There was no significant difference in baseline triglyceride levels between non-survivors (n = 109) and survivors (n = 491) [Median 127 vs. 113 mg/dl, p = 0.213]. However, the non-survivors had significantly higher peak triglyceride levels during hospitalization [Median 179 vs. 134 mg/dl, p < 0.001]. Importantly, hypertriglyceridemia independently associated with mortality [odds ratio=2.3 (95% CI: 1.4-3.7, p = 0.001)], after adjusting for age, gender, obesity, history of hypertension and diabetes, high CRP, high leukocyte count and glucocorticoid treatment in a multivariable logistic regression model.

CONCLUSIONS

Hypertriglyceridemia during hospitalization is independently associated with 2.3 times higher mortality in COVID-19 patients. Prospective studies are needed to independently validate this retrospective analysis.

Therapeutic Anticoagulation with Heparin in Noncritically Ill Patients with Covid-19

BACKGROUND

Thrombosis and inflammation may contribute to the risk of death and complications among patients with coronavirus disease 2019 (Covid-19). We hypothesized that therapeutic-dose anticoagulation may improve outcomes in noncritically ill patients who are hospitalized with Covid-19.

METHODS

In this open-label, adaptive, multiplatform, controlled trial, we randomly assigned patients who were hospitalized with Covid-19 and who were not critically ill (which was defined as an absence of critical care-level organ support at enrollment) to receive pragmatically defined regimens of either therapeutic-dose anticoagulation with heparin or usual-care pharmacologic thromboprophylaxis. The primary outcome was organ support-free days, evaluated on an ordinal scale that combined in-hospital death (assigned a value of -1) and the number of days free of cardiovascular or respiratory organ support up to day 21 among patients who survived to hospital discharge. This outcome was evaluated with the use of a Bayesian statistical model for all patients and according to the baseline d-dimer level.

RESULTS

The trial was stopped when prespecified criteria for the superiority of therapeutic-dose anticoagulation were met. Among 2219 patients in the final analysis, the probability that therapeutic-dose anticoagulation increased organ support-free days as compared with usual-care thromboprophylaxis was 98.6% (adjusted odds ratio, 1.27; 95% credible interval, 1.03 to 1.58). The adjusted absolute between-group difference in survival until hospital discharge without organ support favoring therapeutic-dose anticoagulation was 4.0 percentage points (95% credible interval, 0.5 to 7.2). The final probability of the superiority of therapeutic-dose anticoagulation over usual-care thromboprophylaxis was 97.3% in the high d-dimer cohort, 92.9% in the low d-dimer cohort, and 97.3% in the unknown d-dimer cohort. Major bleeding occurred in 1.9% of the patients receiving therapeutic-dose anticoagulation and in 0.9% of those receiving thromboprophylaxis.

CONCLUSIONS

In noncritically ill patients with Covid-19, an initial strategy of therapeutic-dose anticoagulation with heparin increased the probability of survival to hospital discharge with reduced use of cardiovascular or respiratory organ support as compared with usual-care thromboprophylaxis. (ATTACC, ACTIV-4a, and REMAP-CAP ClinicalTrials.gov numbers, NCT04372589, NCT04505774, NCT04359277, and NCT02735707.).

Therapeutic Anticoagulation with Heparin in Critically Ill Patients with Covid-19

BACKGROUND

Thrombosis and inflammation may contribute to morbidity and mortality among patients with coronavirus disease 2019 (Covid-19). We hypothesized that therapeutic-dose anticoagulation would improve outcomes in critically ill patients with Covid-19.

METHODS

In an open-label, adaptive, multiplatform, randomized clinical trial, critically ill patients with severe Covid-19 were randomly assigned to a pragmatically defined regimen of either therapeutic-dose anticoagulation with heparin or pharmacologic thromboprophylaxis in accordance with local usual care. The primary outcome was organ support-free days, evaluated on an ordinal scale that combined in-hospital death (assigned a value of -1) and the number of days free of cardiovascular or respiratory organ support up to day 21 among patients who survived to hospital discharge.

RESULTS

The trial was stopped when the prespecified criterion for futility was met for therapeutic-dose anticoagulation. Data on the primary outcome were available for 1098 patients (534 assigned to therapeutic-dose anticoagulation and 564 assigned to usual-care thromboprophylaxis). The median value for organ support-free days was 1 (interquartile range, -1 to 16) among the patients assigned to therapeutic-dose anticoagulation and was 4 (interquartile range, -1 to 16) among the patients assigned to usual-care thromboprophylaxis (adjusted proportional odds ratio, 0.83; 95% credible interval, 0.67 to 1.03; posterior probability of futility [defined as an odds ratio <1.2], 99.9%). The percentage of patients who survived to hospital discharge was similar in the two groups (62.7% and 64.5%, respectively; adjusted odds ratio, 0.84; 95% credible interval, 0.64 to 1.11). Major bleeding occurred in 3.8% of the patients assigned to therapeutic-dose anticoagulation and in 2.3% of those assigned to usual-care pharmacologic thromboprophylaxis.

CONCLUSIONS

In critically ill patients with Covid-19, an initial strategy of therapeutic-dose anticoagulation with heparin did not result in a greater probability of survival to hospital discharge or a greater number of days free of cardiovascular or respiratory organ support than did usual-care pharmacologic thromboprophylaxis. (REMAP-CAP, ACTIV-4a, and ATTACC ClinicalTrials.gov numbers, NCT02735707, NCT04505774, NCT04359277, and NCT04372589.).

Characteristics and outcomes of patients on concurrent direct oral anticoagulants and targeted anticancer therapies-TacDOAC registry: Communication from the ISTH SSC Subcommittee on Hemostasis and Malignancy

BACKGROUND

Cancer patients are increasingly prescribed direct oral anticoagulants (DOACs) and targeted anticancer therapies, but limited data are available on the outcomes during concurrent use.

OBJECTIVES

We conducted an international registry through the Scientific and Standardization Committee of the ISTH to evaluate the characteristics, bleeding, and thrombotic outcomes in patients receiving concurrent DOACs and targeted anticancer therapies.

PATIENTS/METHODS

Patients receiving concurrent DOACs for venous thromboembolism (VTE) or atrial fibrillation and selected targeted anticancer therapies were followed for 6 months after the start of concurrent use. Data including patient and cancer characteristics, major bleeding, non-major bleeding events, and venous or arterial thromboses were collected.

RESULTS

Two hundred and two patients were included from six institutions in the United States and Israel. The most common malignancies were hematologic (N = 57, 28.2%), followed by breast (N = 50, 24.8%) and lung (N = 44, 21.8%). The most common anticancer therapies were epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) inhibitors (N = 43, 21.3%), followed by Bruton's tyrosine kinase (BTK) inhibitors (N = 42, 20.8%) and palbociclib (N = 42, 20.8%). During follow-up, there were 9 major bleeding and 12 non-major bleeding events, corresponding to cumulative incidences of 4% (95% confidence interval [CI]: 2-8%) and 6% (95% CI: 3-10%), respectively. The cumulative incidence of major bleeding events was highest in BTK inhibitor users (10%). There were 3 VTE and 2 arterial thromboses, corresponding to cumulative incidences of 1.5% (95% CI: 0.4-4.0%) and 1.0% (95% CI: 0.2-3.3%), respectively.

CONCLUSIONS

In this cohort receiving concurrent DOACs and targeted anticancer therapies, the incidence of bleeding is higher compared to thrombosis, particularly with BTK inhibitors. Future larger prospective studies are needed.

Developing Treatment Guidelines During a Pandemic Health Crisis: Lessons Learned From COVID-19

The development of the National Institutes of Health (NIH) COVID-19 Treatment Guidelines began in March 2020 in response to a request from the White House Coronavirus Task Force. Within 4 days of the request, the NIH COVID-19 Treatment Guidelines Panel was established and the first meeting took place (virtually-as did subsequent meetings). The Panel comprises 57 individuals representing 6 governmental agencies, 11 professional societies, and 33 medical centers, plus 2 community members, who have worked together to create and frequently update the guidelines on the basis of evidence from the most recent clinical studies available. The initial version of the guidelines was completed within 2 weeks and posted online on 21 April 2020. Initially, sparse evidence was available to guide COVID-19 treatment recommendations. However, treatment data rapidly accrued based on results from clinical studies that used various study designs and evaluated different therapeutic agents and approaches. Data have continued to evolve at a rapid pace, leading to 24 revisions and updates of the guidelines in the first year. This process has provided important lessons for responding to an unprecedented public health emergency: Providers and stakeholders are eager to access credible, current treatment guidelines; governmental agencies, professional societies, and health care leaders can work together effectively and expeditiously; panelists from various disciplines, including biostatistics, are important for quickly developing well-informed recommendations; well-powered randomized clinical trials continue to provide the most compelling evidence to guide treatment recommendations; treatment recommendations need to be developed in a confidential setting free from external pressures; development of a user-friendly, web-based format for communicating with health care providers requires substantial administrative support; and frequent updates are necessary as clinical evidence rapidly emerges.

Antithrombotic Therapy for VTE Disease: Second Update of the CHEST Guideline and Expert Panel Report - Executive Summary

BACKGROUND

This is the second update to the 9^th edition of these guidelines. We provide recommendations on 17 PICO (Patients, Interventions, Comparators, Outcomes) questions, four of which have not been addressed previously.

METHODS

We generate strong and weak recommendations based on high, moderate, and low-certainty evidence, using GRADE methodology.

RESULTS

The panel generated 29 guidance statements, 13 of which are graded as strong recommendations, covering aspects of antithrombotic management of venous thromboembolism from initial management through secondary prevention and risk reduction of post-thrombotic syndrome. Four new guidance statements are added that did not appear in the 9^th edition (2012) or first update (2016). Eight statements have been substantially modified from the first update.

CONCLUSION

New evidence has emerged since 2016 which further informs the standard of care for patients with venous thromboembolism. Substantial uncertainty remains regarding important management questions, particularly in limited disease and special patient populations.

Heparin for Moderately Ill Patients with Covid-19

Background

Heparin, in addition to its anticoagulant properties, has anti-inflammatory and potential anti-viral effects, and may improve endothelial function in patients with Covid-19. Early initiation of therapeutic heparin could decrease the thrombo-inflammatory process, and reduce the risk of critical illness or death.

Methods

We randomly assigned moderately ill hospitalized ward patients admitted for Covid-19 with elevated D-dimer level to therapeutic or prophylactic heparin. The primary outcome was a composite of death, invasive mechanical ventilation, non-invasive mechanical ventilation or ICU admission. Safety outcomes included major bleeding. Analysis was by intention-to-treat.

Results

At 28 days, the primary composite outcome occurred in 37 of 228 patients (16.2%) assigned to therapeutic heparin, and 52 of 237 patients (21.9%) assigned to prophylactic heparin (odds ratio, 0.69; 95% confidence interval [CI], 0.43 to 1.10; p=0.12). Four patients (1.8%) assigned to therapeutic heparin died compared with 18 patients (7.6%) assigned to prophylactic heparin (odds ratio, 0.22; 95%-CI, 0.07 to 0.65). The composite of all-cause mortality or any mechanical ventilation occurred in 23 (10.1%) in the therapeutic heparin group and 38 (16.0%) in the prophylactic heparin group (odds ratio, 0.59; 95%-CI, 0.34 to 1.02). Major bleeding occurred in 2 patients (0.9%) with therapeutic heparin and 4 patients (1.7%) with prophylactic heparin (odds ratio, 0.52; 95%-CI, 0.09 to 2.85).

Conclusions

In moderately ill ward patients with Covid-19 and elevated D-dimer level, therapeutic heparin did not significantly reduce the primary outcome but decreased the odds of death at 28 days. Trial registration numbers: NCT04362085 ; NCT04444700.

Bariatric surgery in patients with advanced heart failure: A proposed multi-disciplinary pathway for surgical care in medically complex patients

BACKGROUND

The objective of this study was to develop a multi-disciplinary care pathway to minimize perioperative complications in patients with advanced heart failure undergoing bariatric surgery. Patients with severe obesity and heart failure carry increased perioperative surgical risk compared to patients with no heart failure due to the severity of their cardiac disease state and associated comorbidities. Our bariatric program routinely excluded patients with advanced heart failure from undergoing bariatric surgery due to the high reported perioperative risk. However, knowing the potential beneficial impact of bariatric surgery for advanced heart failure, our program hoped that the thoughtful development of a perioperative pathway before inclusion of patients with advanced heart failure in the bariatric surgery program could minimize the morbidity of these high-risk patients in comparison to prior publications in the literature.

METHODS

Two multi-disciplinary care pathways were developed, including advanced heart failure, anticoagulation specialists, and transplant cardiologists, to optimize bariatric care for severely obese patients with advanced heart failure with or without mechanical circulatory support and implementation was evaluated for short-term 30-day complications and 6 month cardiac and weight-loss outcomes.

RESULTS

Two multi-disciplinary care pathways were developed and implemented on 5 patients with heart failure with reduced ejection fraction (pathway 1) and 3 patients requiring mechanical circulatory support (pathway 2). There were no in-hospital complications or mortality following either pathway, and there was only 1 emergency room visit and 1 re-admission. The average length of stay for patients with heart failure with reduced ejection fraction without mechanical circulatory support was 2.4 days and for heart failure with reduced ejection fraction with mechanical circulatory support was 4.3 days. Three patients met body mass index criteria for transplant listing at 6 months. Ejection fraction increased an average of 9% at 6 months postoperatively for patients with heart failure with reduced ejection fraction not requiring mechanical circulatory support.

CONCLUSION

With multi-disciplinary care pathway development designed to maximize safety by intensely supporting preoperative cardiac optimization and medication titration postoperatively, bariatric surgery can be performed in patients with advanced heart failure with or without mechanical circulatory support, allowing patients the opportunity for weight loss as a bridge to transplant or potentially meaningful cardiac recovery.

SARS-CoV-2 receptor binding domain-specific antibodies activate platelets with features resembling the pathogenic antibodies in heparin-induced thrombocytopenia

Severe COVID-19 is associated with unprecedented thromboembolic complications. We found that hospitalized COVID-19 patients develop immunoglobulin Gs (IgGs) that recognize a complex consisting of platelet factor 4 and heparin similar to those developed in heparin-induced thrombocytopenia and thrombosis (HIT), however, independent of heparin exposure. These antibodies activate platelets in the presence of TLR9 stimuli, stimuli that are prominent in COVID-19. Strikingly, 4 out of 42 antibodies cloned from IgG1+ RBD-binding B cells could activate platelets. These antibodies possessed, in the heavy-chain complementarity-determining region 3, an RKH or Y5 motif that we recently described among platelet-activating antibodies cloned from HIT patients. RKH and Y5 motifs were prevalent among published RBD-specific antibodies, and 3 out of 6 such antibodies tested could activate platelets. Features of platelet activation by these antibodies resemble those by pathogenic HIT antibodies. B cells with an RKH or Y5 motif were robustly expanded in COVID-19 patients. Our study demonstrates that SARS-CoV-2 infection drives the development of a subset of RBD-specific antibodies that can activate platelets and have activation properties and structural features similar to those of the pathogenic HIT antibodies.

Treatment of catheter-related thrombosis in patients with hematologic malignancies: A Venous thromboEmbolism Network U.S. retrospective cohort study

INTRODUCTION

Optimal treatment of catheter-related thrombosis (CRT) is uncertain in patients with hematologic malignancy. We aimed to evaluate the treatment strategies, outcomes, and predictors of recurrent venous thromboembolism (VTE) associated with catheter-related thrombosis (CRT) in patients with hematologic malignancy.

METHODS

We performed a multicenter retrospective cohort study of eight institutions through the Venous thromboEmbolism Network US. Patients with hematologic malignancies with documented CRT were identified using ICD-9 and ICD-10 diagnostic codes. Semi-competing risks proportional hazard regression models were created.

RESULTS AND CONCLUSIONS

Of the 663 patients in the cohort, 124 (19%) were treated with anticoagulation alone, 388 (58%) were treated with anticoagulation and catheter removal, 119 (18%) treated with catheter removal only, and 32 (5%) had neither catheter removal nor anticoagulation. 100 (15%) patients experienced a recurrent VTE event. In the 579 patients who had catheter removal, the most common reason for catheter removal was the CRT [392 (68%)]. For subjects who received any anticoagulation (n = 512), total anticoagulation duration was not associated with VTE recurrence [1.000 (0.999-1.002)]. After adjustment patients treated with catheter removal only had an increased risk of VTE recurrence [2.50 (1.24-5.07)] and death [4.96 (2.47-9.97)]. Patients with no treatment had increased risk of death [16.81 (6.22-45.38)] and death after VTE recurrence [27.29 (3.13-238.13)]. In this large, multicenter retrospective cohort, we found significant variability in the treatment of CRT in patients with hematologic malignancy. Treatment without anticoagulation was associated with recurrent VTE.

Coagulopathy of hospitalised COVID-19: A Pragmatic Randomised Controlled Trial of Therapeutic Anticoagulation versus Standard Care as a Rapid Response to the COVID-19 Pandemic (RAPID COVID COAG - RAPID Trial): A structured summary of a study protocol for a randomised controlled trial

Objectives

To determine the effect of therapeutic anticoagulation, with low molecular weight heparin (LMWH) or unfractionated heparin (UFH, high dose nomogram), compared to standard care in hospitalized patients admitted for COVID-19 with an elevated D-dimer on the composite outcome of intensive care unit (ICU) admission, non-invasive positive pressure ventilation, invasive mechanical ventilation or death up to 28 days.

Trial design

Open-label, parallel, 1:1, phase 3, 2-arm randomized controlled trial

Participants

The study population includes hospitalized adults admitted for COVID-19 prior to the development of critical illness. Excluded individuals are those where the bleeding risk or risk of transfusion would generally be considered unacceptable, those already therapeutically anticoagulated and those who have already have any component of the primary composite outcome. Participants are recruited from hospital sites in Brazil, Canada, Ireland, Saudi Arabia, United Arab Emirates, and the United States of America.

The inclusion criteria are:

Laboratory confirmed COVID-19 (diagnosis of SARS-CoV-2 via reverse transcriptase polymerase chain reaction as per the World Health Organization protocol or by nucleic acid based isothermal amplification) prior to hospital admission OR within first 5 days (i.e. 120 hours) after hospital admission;

Admitted to hospital for COVID-19;

One D-dimer value above the upper limit of normal (ULN) (within 5 days (i.e. 120 hours) of hospital admission) AND EITHER:

D-Dimer ≥2 times ULN OR

D-Dimer above ULN and Oxygen saturation ≤ 93% on room air;

> 18 years of age;

Informed consent from the patient (or legally authorized substitute decision maker).

The exclusion criteria are:

pregnancy;

hemoglobin <80 g/L in the last 72 hours;

platelet count <50 x 10⁹/L in the last 72 hours;

known fibrinogen <1.5 g/L (if testing deemed clinically indicated by the treating physician prior to the initiation of anticoagulation);

known INR >1.8 (if testing deemed clinically indicated by the treating physician prior to the initiation of anticoagulation);

patient already prescribed intermediate dosing of LMWH that cannot be changed (determination of what constitutes an intermediate dose is to be at the discretion of the treating clinician taking the local institutional thromboprophylaxis protocol for high risk patients into consideration);

patient already prescribed therapeutic anticoagulation at the time of screening [low or high dose nomogram UFH, LMWH, warfarin, direct oral anticoagulant (any dose of dabigatran, apixaban, rivaroxaban, edoxaban)];

patient prescribed dual antiplatelet therapy, when one of the agents cannot be stopped safely;

known bleeding within the last 30 days requiring emergency room presentation or hospitalization;

known history of a bleeding disorder of an inherited or active acquired bleeding disorder;

known history of heparin-induced thrombocytopenia;

known allergy to UFH or LMWH;

admitted to the intensive care unit at the time of screening;

treated with non-invasive positive pressure ventilation or invasive mechanical ventilation at the time of screening;

Imminent death according to the judgement of the most responsible physician;

enrollment in another clinical trial of antithrombotic therapy involving hospitalized patients.

Intervention and comparator

Intervention: Therapeutic dose of LMWH (dalteparin, enoxaparin, tinzaparin) or high dose nomogram of UFH. The choice of LMWH versus UFH will be at the clinician’s discretion and dependent on local institutional supply.

Comparator: Standard care [thromboprophylactic doses of LMWH (dalteparin, enoxaparin, tinzaparin, fondaparinux)] or UFH. Administration of LMWH, UFH or fondaparinux at thromboprophylactic doses for acutely ill hospitalized medical patients, in the absence of contraindication, is generally considered standard care.

Main outcomes

The primary composite outcome of ICU admission, non-invasive positive pressure ventilation, invasive mechanical ventilation or death at 28 days.

Secondary outcomes include (evaluated up to day 28):

All-cause death

Composite of ICU admission or all-cause death

Composite of mechanical ventilation or all-cause death

Major bleeding as defined by the ISTH Scientific and Standardization Committee (ISTH-SSC) recommendation;

Red blood cell transfusion (>1 unit);

Transfusion of platelets, frozen plasma, prothrombin complex concentrate, cryoprecipitate and/or fibrinogen concentrate;

Renal replacement therapy;

Hospital-free days alive;

ICU-free days alive;

Ventilator-free days alive;

Organ support-free days alive;

Venous thromboembolism (defined as symptomatic or incidental, suspected or confirmed via diagnostic imaging and/or electrocardiogram where appropriate);

Arterial thromboembolism (defined as suspected or confirmed via diagnostic imaging and/or electrocardiogram where appropriate);

Heparin induced thrombocytopenia;

Trajectories of COVID-19 disease-related coagulation and inflammatory biomarkers.

Randomisation

Randomisation will be stratified by site and age (>65 versus ≤65 years) using a 1:1 computer-generated random allocation sequence with variable block sizes. Randomization will occur within the first 5 days (i.e. 120 hours) of participant hospital admission. However, it is recommended that randomization occurs as early as possible after hospital admission. Central randomization using an interactive web response system will ensure allocation concealment.

Blinding (masking)

No blinding involved. This is an open-label trial.

Numbers to be randomised (sample size)

462 patients (231 per group) are needed to detect a 15% risk difference, from 50% in the control group to 35% in the experimental group, with power of 90% at a two-sided alpha of 0.05.

Trial Status

Protocol Version Number 1.4. Recruitment began on May 11^th, 2020. Recruitment is expected to be completed March 2022. Recruitment is ongoing.

Trial registration

ClinicalTrials.gov Identifier: NCT04362085

Date of Trial Registration: April 24, 2020

Full protocol

The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest of expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05076-0.

Red blood cell transfusion does not increase risk of venous or arterial thrombosis during hospitalization

Previous observational studies suggest associations between red blood cell (RBC) transfusion and risk for arterial or venous thrombosis. We determined the association between thrombosis and RBC transfusion in hospitalized patients using the Recipient Database from the National Heart Lung and Blood Institute (NHLBI) Recipient Epidemiology and Donor Evaluation Study-III. A thrombotic event was a hospitalization with an arterial or venous thrombosis ICD-9 code and administration of a therapeutic anticoagulant or antiplatelet agent. Patients with history of thrombosis or a thrombosis within 24 hours of admission were excluded. A proportional hazards regression model with time-dependent covariates was calculated. Estimates were adjusted for age, sex, hospital, smoking, medical comorbidities, and surgical procedures. Of 657 412 inpatient admissions, 67 176 (10.2%) received at least one RBC transfusion. Two percent (12927) of patients experienced a thrombosis. Of these, 2587 developed thrombosis after RBC transfusion. In unadjusted analyses, RBC transfusion was associated with an increased thrombosis risk [HR = 1.3 (95% CI 1.23-1.36)]. After adjustment for surgical procedures, age, sex, hospital, and comorbidities, no association between RBC transfusion on risk of venous and arterial thrombosis was found [HR 1.0 (95% CI: 0.96-1.05)]. Thus, RBC transfusion does not appear to be an important risk factor for thrombosis in most hospitalized patients.

North American Physician Practice Patterns in the Management of Anticoagulation in Pregnancy

Background: During pregnancy and in the postpartum period women are at increased risk of venous thromboembolism (VTE) owing to hypercoagulability and mechanical issues, as well as nonpregnancy conditions including inherited and acquired thrombophilia. Although guidelines exist for the use of thromboprophylaxis in this setting, there are differences in the specifics of the recommendations among expert societies. We assessed the current practice patterns of North American providers in the prevention of pregnancy-associated VTE in women with thrombophilia. Methods: A survey was created and distributed with case studies and questions addressing VTE prevention during the antepartum and postpartum periods. Results: Surveys were completed by 28% of adult providers queried, with broad geographic representation. There was consistent use of a prophylactic dose of low-molecular weight heparin (LMWH) ante- and postpartum for individuals with low-risk thrombophilia and past estrogen-provoked VTE but a lack of a consensus of anticoagulant (AC) use and dose in individuals with higher risk thrombophilia. There was variability in the dose selection and monitoring of AC when using induction versus spontaneous labor, with 47% of providers switching from LMWH to unfractionated heparin for those not having a scheduled delivery, and there were differences in the duration of postpartum prophylaxis based upon delivery mode. Conclusion: In this survey of North American experienced specialists' responses to a variety of commonly encountered scenarios of thrombophilia and pregnancy and the management of AC were not always consistent with published guidelines.

Anticoagulation practice patterns in COVID-19: A global survey

Background

Best practice for prevention, diagnosis, and management of venous thromboembolism (VTE) in patients with coronavirus disease 2019 (COVID-19) is unknown due to limited published data in this population.

Objectives

We aimed to assess current global practice and experience in management of COVID-19-associated coagulopathy to identify information to guide prospective and randomized studies.

Methods

Physicians were queried about their current approach to prophylaxis, diagnosis, and treatment of VTE in patients with COVID-19 using an online survey tool distributed through multiple international organizations between April 10 and 14, 2020.

Results

Five hundred fifteen physicians from 41 countries responded. The majority of respondents (78%) recommended prophylactic anticoagulation for all hospitalized patients with COVID-19, with most recommending use of low-molecular-weight heparin or unfractionated heparin. Significant practice variation was found regarding the need for dose escalation of anticoagulation outside the setting of confirmed or suspected VTE. Respondents reported the use of bedside testing when unable to perform standard diagnostic imaging for diagnosis of VTE. Two hundred ninety-one respondents reported observing thrombotic complications in their patients, with 64% noting that the complication was pulmonary embolism. Of the 44% of respondents who estimated incidence of thrombosis in patients with COVID-19 in their hospital, estimates ranged widely from 1% to 50%. One hundred seventy-four respondents noted bleeding complications (34% minor bleeding, 14% clinically relevant nonmajor bleeding, and 12% major bleeding).

Conclusion

Well-designed epidemiologic studies are urgently needed to understand the incidence and risk factors of VTE and bleeding complications in patients with COVID-19. Randomized clinical trials addressing use of anticoagulation are also needed.

Patient Safety Indicator-12 Rarely Identifies Problems with Quality of Care in Perioperative Venous Thromboembolism

BACKGROUND

Patient safety indicators (PSI) were developed for hospitals to screen for healthcare-associated adverse events. PSIs are believed to be preventable and have become a part of major pay-for-performance programs. PSI-12 captures perioperative venous thromboembolism (VTE), which contributes to morbidity and mortality of hospitalized patients. We aimed to evaluate PSI-12 events at our institution to identify areas for improvement of perioperative VTE prevention.

METHODS

We identified PSI-12 events from June 2015 to June 2017 using the Agency for Healthcare Research and Quality software version 5. Events were reviewed using our electronic medical record to identify further details of each event.

RESULTS

A total of 154 perioperative VTE cases were analyzed in the 2-year period. Pulmonary embolism (PE) occurred in 62.9% of cases, deep venous thrombosis (DVT) in 24%, and concurrent DVT/PE in 12.9%. The mean age of patients was 56 years old. Deficiencies in guideline-appropriate prophylaxis were identified in only 17 (11%) of cases. Unfractionated heparin was used in 61 cases, enoxaparin in 31 cases, and nine events occurred on therapeutic anticoagulation. Mechanical prophylaxis was used in 51 cases because of bleeding risk, thrombocytopenia, and/or liver associated coagulopathy. Four events occurred prior to the index procedure, with another eight cases occurring intraoperatively, or on the day of the procedure.

CONCLUSIONS

PSI-12 has several limitations in identifying quality of care issues in perioperative VTE. While it may be useful as a screening tool, further research for improvements are needed if it will remain one of the key measures in pay-for-performance.

Adult and pediatric mechanical circulation: a guide for the hematologist

Mechanical circulatory support (MCS) is the overarching term that encompasses the temporary and durable devices used in patients with severe heart failure. MCS disturbs the hematologic and coagulation system, leading to platelet activation, activation of the contact pathway of coagulation, and acquired von Willebrand syndrome. Ischemic stroke and major hemorrhage occur in up to 30% of patients. Hematologists are an essential part of the MCS team because they understand the delicate balance between bleeding and clotting and alteration of hemostasis with antithrombotic therapy. However, prior to this important collaborative role, learning the terminology used in the field and types of MCS devices allows improved communication with the MCS team and best patient care. Understanding which antithromobotic therapies are used at baseline is also required to provide recommendations if hemorrhage or thrombosis occurs. Additional challenging consultations in MCS patients include the influence of thrombophilia on the risk for thrombosis and management of heparin-induced thrombocytopenia. This narrative review will provide a foundation to understand MCS devices how to prevent, diagnose, and manage MCS thrombosis for the practicing hematologist.

Venous Thromboembolism: A Survey of Oral Anticoagulant Preferences in the Treatment of Challenging Patient Populations

Venous thromboembolism (VTE) is a highly morbid condition with several available oral anticoagulant treatment options. Numerous studies have been published comparing warfarin to direct oral anticoagulants; however, several populations remain underrepresented in these reports. We surveyed members of The Venous ThromboEmbolism Network U.S. working group regarding their oral anticoagulant preferences for the treatment of VTE in different and challenging populations. In individuals with VTE and no other medical comorbidities, respondents preferred either rivaroxaban (48.7%) or apixaban (48.7%). Apixaban (53.3%) was preferred in elderly individuals with an increased risk of bleeding. Warfarin was preferred in individuals with liver or kidney dysfunction (42% and 47%), altered metabolism (>55%), and antiphospholipid antibody syndrome (84.2%). Low-molecular-weight heparin was preferred in individuals with malignancy (56.6%), followed by edoxaban (23.7%). These findings may help guide clinicians when choosing an anticoagulant in these challenging situations and demonstrate the urgent need for additional study in these groups.

Disease burden, complication rates, and health-care costs of heparin-induced thrombocytopenia in the USA: a population-based study

BACKGROUND

Heparin-induced thrombocytopenia can be a life-threatening and limb-threatening complication of heparin therapy. Incidence and complication rates of this condition have been extrapolated from studies with modest sample sizes, and despite the availability of therapeutic interventions the outcomes of heparin-induced thrombocytopenia are not well understood. We aimed to estimate disease burden, complication rates, and costs of heparin-induced thrombocytopenia in the USA.

METHODS

In this population-based study we analysed data from 2009 to 2013 from the Nationwide (National) Inpatient Sample (NIS), a large, all-payer inpatient health-care database in the USA. To validate the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code for heparin-induced thrombocytopenia (289.84), we defined the sensitivity and specificity of this code using patient data from 2013 from a local hospital (Froedtert Memorial Lutheran Hospital, Milwaukee, WI, USA). The primary outcomes assessed were the incidence of hospital discharges with codes for heparin-induced thrombocytopenia and of discharges for heparin-induced thrombocytopenia associated with cardiopulmonary bypass, haemodialysis, hip or knee arthroplasty, trauma or injury (or both), and gingival or periodontal disease (or both). We also assessed the incidence of thrombosis, bleeding, limb or digit amputation, mortality, length of hospital stay, and associated hospital charges.

FINDINGS

Between 2009 and 2013, 97 566 discharges from the NIS assigned the ICD-9-CM code for heparin-induced thrombocytopenia, and 149 911 247 discharges coded for non-heparin-induced thrombocytopenia, were analysed. Overall, heparin-induced thrombocytopenia was identified in 97 566 (0·065%; SE 0·0012) of 150 008 813 discharges, corresponding to approximately one in 1500 hospital admissions. Patients undergoing cardiopulmonary bypass had the highest rates of heparin-induced thrombocytopenia (7702 [0·63%; SE 0·03] of 1 230 362), followed by those undergoing haemodialysis (23 012 [0·47%; 0·01] of 4 908 100), those with gingival or periodontal disease, or both (106 [0·12%; 0·03] of 88 621), and those with trauma or injury, or both (541 [0·09%; 0·01] of 602 944); patients with hip (845 [0·04%; 0·004] of 1 943 353) and knee (676 [0·02%; 0·002] of 3 022 602) arthroplasty had the lowest rates of heparin-induced thrombocytopenia. Thrombosis (29 079 [29·8%; SE 0·4] of 97 566) and bleeding (6044 [6·2%; 0·2] of 97 566) were common complications in heparin-induced thrombocytopenia, and 1446 (23·9%; 1·2) of 6044 patients with heparin-induced thrombocytopenia who had haemorrhage died. 742 (0·76%; SE 0·06) of 97 566 patients with heparin-induced thrombocytopenia discharges underwent amputations compared with 173 043 (0·12%; 0·001) of 149 911 247 with non-heparin-induced thrombocytopenia discharges (adjusted odds ratio 5·095 [95% CI 4·309-6·023]; p<0·0001). Overall, in-hospital mortality was 9842 (10·1%; SE 0·2) of 97 508 in discharge summaries coded for heparin-induced thrombocytopenia compared with 3 206 700 (2·1%; 0·01) of 149 811 891 in discharges for non-heparin-induced thrombocytopenia (adjusted odds ratio 4·075 [95% CI 3·846-4·317]; p<0·0001). The median length of stay among live discharges was 8·9 days (IQR 4·6-17·1) and total hospital charges were US$83 072 (IQR 37 240-188 419) for heparin-induced thrombocytopenia discharges compared with 2·6 days (1·4-4·8) and $21 360 (11 426-41 917) for non-heparin-induced thrombocytopenia discharges (p<0·0001 for both). 333 discharges from a local hospital were analysed to assess the diagnostic sensitivity and specificity of the heparin-induced thrombocytopenia ICD-9-CM code; sensitivity was 90·9% (95% CI 57·1-99·5) and specificity was 94·4% (91·1-96·6).

INTERPRETATION

Complication rates for heparin-induced thrombocytopenia remain high and more effective preventive and treatment interventions are needed.

FUNDING

None.

Initial strides for invent-VTE: Towards global collaboration to accelerate clinical research in venous thromboembolism

Venous thromboembolism (VTE) represents a major global burden of disease and requires collaborative efforts to conduct large, high-quality investigator-initiated and academically sponsored studies addressing the most relevant clinical questions. Owing to increasing regulatory requirements, the highly competitive nature of peer-reviewed funding and costs associated with conducting large, multinational clinical trials, completing practice-changing research constitutes a growing challenge for clinical investigators. As clinical trialists interested in VTE, we founded INVENT (International Network of Venous Thromboembolism Clinical Research Networks) in an effort to promote and accelerate patient-oriented, investigator-initiated, international collaborative research, to identify, prioritize and answer key clinical research questions for patients with VTE. We report on our activities to formalize the INVENT network and our accomplishments in our first year.

The impact of Agent Orange exposure on prognosis and management in patients with chronic lymphocytic leukemia: a National Veteran Affairs Tumor Registry Study

Exposure to Agent Orange (AO) has been associated with the development of chronic lymphocytic leukemia (CLL). We performed a retrospective study of 2052 Vietnam veterans identified in the National VA Tumor Registry to assess the impact of AO exposure on CLL prognosis, treatment and survival. Prognostic factors did not differ based on exposure. Veterans exposed to AO were diagnosed younger (63.2 vs. 70.5 years, p < .0001) and had longer overall survival (median not reached vs. 91 months, p < .001). This prolonged survival was in the subgroups of patients aged 60-69 years (p< .0001) and those with 11q deletion (p < .0001). Those exposed to AO were more likely to be treated with fludarabine, chlorambucil and rituximab (38 vs. 21%, p < .001) and bendamustine plus rituximab (25 vs. 18%, p = 0.039) as first line therapy. Exposure to AO was not associated with either poor prognostic factors or shortened overall survival in our large veteran population with CLL.

Impact of treatment and outcomes for patients with posttransplant drug-associated thrombotic microangiopathy

BACKGROUND

Drug-induced transplant-associated thrombotic microangiopathy (DTA-TMA) is a rare but serious complication that can occur after hematopoietic cell transplantation (HCT) or solid organ transplantation (SOT) without guidelines for optimal management of this condition.

STUDY DESIGN AND METHODS

Given the ambiguity surrounding the treatment for DTA-TMA, we conducted a retrospective review to evaluate the impact of different treatment strategies in DTA-TMA patients. Our primary endpoint was to determine the overall response rate (ORR) for DTA-TMA based on the type of treatment modality chosen while secondary endpoints included the time to response, relapse rates, and overall survival for DTA-TMA cases.

RESULTS

There were a total of 14 DTA-TMA patients of whom nine were post-HCT and five were post-SOT. Most of the DTA-TMA cases were due to tacrolimus (n = 11) with a minority related to sirolimus (n = 3). A total of nine of 14 patients demonstrated response and five had no response to therapy. The ORR among the DTA-TMA patients after HCT and SOT who received plasma exchange (PLEX) were 25 and 100%, respectively. The ORRs among the patients (includes HCT and SOT) who received rituximab (n = 3) and eculizumab (n = 5) were 67 and 60%, respectively. There were two relapses noted in our study and both were in the HCT group.

CONCLUSION

While discontinuation of the offending agent may be sufficient for treatment of DTA-TMA after HCT, PLEX may be a reasonable option for DTA-TMA after SOT. Although the results are encouraging with rituximab and eculizumab in the treatment of DTA-TMA, larger prospective studies are needed to validate our findings.