Venous thromboembolism in hematopoietic stem cell transplant recipients

Hemostasis and complement in allogeneic hematopoietic stem cell transplantation: clinical significance of two interactive systems

Hematopoietic stem cell transplantation (HCT) represents a curative treatment option for certain malignant and nonmalignant hematological diseases. Conditioning regimens before HCT, the development of graft-versus-host disease (GVHD) in the allogeneic setting, and delayed immune reconstitution contribute to early and late complications by inducing tissue damage or humoral alterations. Hemostasis and/or the complement system are biological regulatory defense systems involving humoral and cellular reactions and are variably involved in these complications after allogeneic HCT. The hemostasis and complement systems have multiple interactions, which have been described both under physiological and pathological conditions. They share common tissue targets, such as the endothelium, which suggests interactions in the pathogenesis of several serious complications in the early or late phase after HCT. Complications in which both systems interfere with each other and thus contribute to disease pathogenesis include transplant-associated thrombotic microangiopathy (HSCT-TMA), sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD), and GVHD. Here, we review the current knowledge on changes in hemostasis and complement after allogeneic HCT and how these changes may define clinical impact.

International recommendations for screening and preventative practices for long-term survivors of transplantation and cellular therapy: a 2023 update

As hematopoietic cell transplantation (HCT) and cellular therapy expand to new indications and international access improves, the volume of HCT performed annually continues to rise. Parallel improvements in HCT techniques and supportive care entails more patients surviving long-term, creating further emphasis on survivorship needs. Survivors are at risk for developing late complications secondary to pre-, peri- and post-transplant exposures and other underlying risk-factors. Guidelines for screening and preventive practices for HCT survivors were originally published in 2006 and updated in 2012. To review contemporary literature and update the recommendations while considering the changing practice of HCT and cellular therapy, an international group of experts was again convened. This review provides updated pediatric and adult survivorship guidelines for HCT and cellular therapy. The contributory role of chronic graft-versus-host disease (cGVHD) to the development of late effects is discussed but cGVHD management is not covered in detail. These guidelines emphasize special needs of patients with distinct underlying HCT indications or comorbidities (e.g., hemoglobinopathies, older adults) but do not replace more detailed group, disease, or condition specific guidelines. Although these recommendations should be applicable to the vast majority of HCT recipients, resource constraints may limit their implementation in some settings.

International Recommendations for Screening and Preventative Practices for Long-Term Survivors of Transplantation and Cellular Therapy: A 2023 Update

As hematopoietic cell transplantation (HCT) and cellular therapy expand to new indications and international access improves, the number of HCTs performed annually continues to rise. Parallel improvements in HCT techniques and supportive care entails more patients surviving long term, creating further emphasis on survivorship needs. Survivors are at risk for developing late complications secondary to pretransplantation, peritransplantation, and post-transplantation exposures and other underlying risk factors. Guidelines for screening and preventive practices for HCT survivors were originally published in 2006 and then updated in 2012. An international group of experts was convened to review the contemporary literature and update the recommendations while considering the changing practices of HCT and cellular therapy. This review provides updated pediatric and adult survivorship guidelines for HCT and cellular therapy. The contributory role of chronic graft-versus-host disease (cGVHD) to the development of late effects is discussed, but cGVHD management is not covered in detail. These guidelines emphasize the special needs of patients with distinct underlying HCT indications or comorbidities (eg, hemoglobinopathies, older adults) but do not replace more detailed group-, disease-, or condition-specific guidelines. Although these recommendations should be applicable to the vast majority of HCT recipients, resource constraints may limit their implementation in some settings.

Characterization of direct oral anticoagulants use in adult hematopoietic stem cell transplant recipients

Direct oral anticoagulants (DOACs) for venous thromboembolism (VTE) treatment are of interest in oncology due to ease of administration and lack of need for therapeutic monitoring compared to other anticoagulants. Data supporting their use in patients with hematologic malignancies post-hematopoietic stem cell transplant (HCT) are limited. The purpose of the study is to characterize DOAC use in HCT patients. This multicenter, retrospective cohort analysis included allogeneic and autologous HCT recipients. The primary outcome was major bleeding. Secondary outcomes included clinically relevant non-major bleeding (CRNMB)/minor bleeding and VTE recurrence. Of 126 patients, 91 (72.2%) patients received an autologous HCT, and 35 (27.8%) patients received an allo-HCT. No major bleeding occurred in either transplant recipient groups. In autologous HCT recipients, CRNMB/minor bleeding occurred in four (4.4%) patients and VTE recurrence occurred in one (1.1%) patient. For allogeneic HCT recipients, CRNMB/minor bleeding occurred in five (14.3%) patients and VTE recurrence occurred in two (5.7%) patients. For patients that experienced a CRNMB, five (100%) of the allogeneic HCT and two (50%) of the autologous HCT recipients were thrombocytopenic at the time of bleeding. Only 38.5% of patients who experienced a drug-drug interaction requiring DOAC dose adjustment received the appropriate dose adjustment. DOACs were associated with low rates of recurrent VTE and no major bleeding events, similar to published data on DOAC use in the general cancer patient population. This suggests that DOACs may be safe therapeutic options with proactive management of drug interactions and careful monitoring for bleeding events, especially in the allogeneic HCT population where minor bleeding rates were slightly higher.

Efficacy and Safety of a DOAC Compared to Unfractionated Heparin and A Low Molecular Weight Heparin in the Prevention of Thromboembolism in Hematopoietic Stem Cell Transplant Recipients

Background

Hematopoietic stem cell transplantation (HSCT) patients are at risk of thromboembolic events, making thromboprophylaxis crucial.

Objectives

This study aimed to compare apixaban, a direct factor Xa inhibitor (DOAC), with dalteparin and unfractionated heparin for thromboprophylaxis in HSCT recipients. The safety outcome included the assessment of hemorrhagic events.

Methods

In this open-label randomized clinical trial, 182 HSCT recipients were divided into three groups: Apixaban (n = 61, 2.5 mg two times a day), dalteparin (n = 59, 5000 IU daily), and unfractionated heparin (n = 62, 5000 IU twice daily). These anticoagulant regimens were administered after central vein catheterization and during hospitalization. The primary clinical outcome was the risk of thrombosis, and the secondary outcome was the rate of bleeding. Relevant laboratory results were analyzed using appropriate statistical tests.

Results

Among the 61 patients in the apixaban group, six experienced thrombosis (9.83%), with four (6.65%) of them on anticoagulants. In the dalteparin group, three patients (5%) developed thrombosis, two of whom (3.38%) were on anticoagulants. In the heparin group, all four thrombosis cases (6.4%) occurred in patients on anticoagulants (P = 0.543 overall and P = 0.776 in anticoagulant users). Only two cases of bleeding were reported (1.09% overall), one in the dalteparin group (1.69%) and the other in the apixaban group (1.63%).

Conclusions

Apixaban, dalteparin, and heparin demonstrated similar effectiveness in preventing thromboembolism in HSCT recipients. Furthermore, the comparison of bleeding rates across the study groups did not reveal significant differences. Larger studies with higher event rates may yield more precise conclusions.

Integration of Daily Patient-Reported Outcome Measures in Pediatric Stem Cell Transplantation

Patients' reports of their health status are increasingly used in hematopoietic stem cell transplantation (SCT) to better understand the negative impact on symptom burden and quality of life. Little is known regarding the implementation in routine clinical care, particularly how it can be used to improve supportive care. We sought to the evaluate feasibility of capturing daily patient-reported outcomes (PROs) in the acute phase of SCT to measure physical and psychosocial symptom burden. In this single-center prospective observational study, we assessed daily PRO from conditioning to neutrophil engraftment in children (age 1 to 18 year) who underwent allogeneic or autologous SCT for malignant and nonmalignant disease. The most common acute adverse effects of chemotherapy (pain, nausea, loss of appetite, sleep disturbance, and physical performance impairment) were reported daily via ePROtect, a web-based program designed to integrate health responses. From February 2021 to March 2023, 20 children undergoing allogeneic (allo-) SCT (n = 11) or autologous (auto-) SCT (n = 9) and their proxies consented to participation, all of whom were included in this analysis. A total of 359 PRO questionnaires were completed, corresponding to a median daily completion rate of 72.7% (interquartile range, 60.4% to 83.6%). After conditioning, pain perception anticipated the rise of infectious parameters and the development of mucositis, thus initiating supportive treatment. Patients reported the strongest symptom burden at a median of 8.5 days post-transplantation. At 4 weeks post-transplantation, baseline values were restored for all symptoms. There were no significant differences between auto-SCT and allo-SCT, except for nausea and loss of appetite after administration of antithymocyte globulin in allo-SCT. This study empirically documents the daily health status of children undergoing SCT and proposes an attractive modus operandi on how continuous feedback on health-related symptoms can be integrated into daily clinical practice.

Evaluation of venous thromboembolism prophylaxis protocol in hematopoietic cell transplant patients

Hematopoietic cell transplant (HCT) recipients are at risk for thromboembolic and bleeding complications. There is limited evidence regarding the optimal approach to managing venous thromboembolism (VTE) prophylaxis in hospitalized patients undergoing HCT. In this retrospective cohort study, we evaluated the incidence of bleeding and VTE events in hospitalized HCT patients who received VTE prophylaxis per our institution's VTE Prophylaxis Protocol (VPP), with either enoxaparin 40 mg subcutaneously daily or heparin 5 000 units subcutaneously twice daily, compared to historical controls who did not receive VTE prophylaxis. The primary outcome was a composite of major bleeding events, clinically relevant non-major bleeding (CRNMB), and minor bleeding. The secondary outcome was a composite of VTE events. A total of 614 patients were evaluated, including 278 prior to and 336 after implementation of VPP. VTE prophylaxis resulted in no difference in bleeding events (15.1% in the pre-VPP group vs. 14.6% in the post-VPP group, p = 0.86) or composite of major and CRNMB events (0.72% vs. 0.30%, p = 0.59). There was a trend toward lower incidence of VTE events in the post-VPP group which did not reach statistical significance (8.6% vs. 6.0%, p = 0.20). We conclude that VTE prophylaxis does not pose additional bleeding risk in HCT patients.

Venous thromboembolism in hematopoietic stem cell transplantation: A narrative review

Venous thromboembolism (VTE) is a common complication of hematopoietic stem cell transplantation (HSCT) and its treatment has significant effects on morbidity and non-relapse mortality. There is a complex interplay on balancing the risk for thrombosis and bleeding in these patients, making treatment decisions particularly challenging. Despite this, there are currently no validated risk assessment models or guidelines to aid clinical decision making on thromboprophylaxis and VTE treatment in this population of patients. Herein, we review the many risk factors for VTE in HSCT patients, categorized into patient, disease, catheter, treatment, laboratory, and transplant-related variables. This review also discusses current thromboprophylaxis and VTE management strategies in HSCT patients, with scope into the development of risk assessment models that allow for identification of high-risk subgroups who may benefit from targeted intervention.

Direct oral anticoagulants in patients with venous thromboembolism and hematological malignancies

Data are needed on direct oral anticoagulants (DOACs) for the treatment of venous thromboembolism (VTE) in hematological malignancies (HM). Retrospective studies to date lacked a control group and did not focus on patients with VTE. Out aim was to assess the incidence of VTE recurrence and bleeding in HM patients treated with low molecular weight heparin (LMWH) or DOACs for acute VTE. This is a retrospective cohort study including patients with active HM and newly-diagnosed VTE, indexed on the first day of anticoagulation and followed for 12 months. The outcome was a composite of recurrent VTE, major bleeding or clinically relevant non-major bleeding. Cumulative incidence [95% confidence interval (CI)] was calculated for each anticoagulation group (LMWH, DOAC) and hazard ratios (HR) were calculated using cox-proportional hazards model, with death as a competing risk. 143 HM patients treated with LMWH (96) or DOACs (47) for acute VTE were included. The most common HM types were lymphoma in 83 (58%) and plasma cell dyscrasia in 32 (22.3%). The 12-month cumulative incidence of the composite outcome was 24.2% (95% CI 15.9-33.5%; n = 22) in the LMWH group and 18.5% (8.5-31.5%; n = 8) in the DOAC group (HR 1.51 [0.695-3.297]). Two recurrent VTE occurred (both in the DOAC group while off-treatment). Nine (9.4%) LMWH-treated patients had major bleeding compared to 1 (2.1%) DOAC-treated patient (HR 4.85 [0.64-36.56]). This study generates the hypothesis that DOACs may be a safe and effective alternative to LMWH for VTE in patients with HM types represented in the study.

The Role of Complement in HSCT-TMA: Basic Science to Clinical Practice

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy (HSCT-TMA) is a common complication occurring post-HSCT and is associated with substantial morbidity and mortality if not promptly identified and treated. Emerging evidence suggests a central role for the complement system in the pathogenesis of HSCT-TMA. The complement system has also been shown to interact with other pathways and processes including coagulation and inflammation, all of which are activated following HSCT. Three endothelial cell-damaging “hits” are required for HSCT-TMA genesis: a genetic predisposition or existing damage, an endothelial cell-damaging conditioning regimen, and additional damaging insults. Numerous risk factors for the development of HSCT-TMA have been identified (including primary diagnosis, graft type, and conditioning regimen) and validated lists of relatively simple diagnostic signs and symptoms exist, many utilizing routine clinical and laboratory assessments. Despite the relative ease with which HSCT-TMA can be screened for, it is often overlooked or masked by other common post-transplant conditions. Recent evidence that patients with HSCT-TMA may also concurrently present with these differential diagnoses only serve to further confound its identification and treatment. HSCT-TMA may be treated, or even prevented, by removing or ameliorating triggering “hits”, and recent studies have also shown substantial utility of complement-targeted therapies in this patient population. Further investigation into optimal management and treatment strategies is needed. Greater awareness of TMA post-HSCT is urgently needed to improve patient outcomes; the objective of this article is to clarify current understanding, explain underlying complement biology and provide simple tools to aid the early recognition, management, and monitoring of HSCT-TMA.

External validation of the HIGH-2-LOW model: A predictive score for venous thromboembolism after allogeneic transplant

In patients undergoing hematopoietic cell transplantation (HCT), venous thromboembolism (VTE) remains a serious complication that lacks validated risk assessment models (RAMs) to guide thromboprophylaxis. To address this dilemma, we performed a temporal and external validation study of the recently derived HIGH-2-LOW RAM. We selected adult patients undergoing allogeneic HCT from Fred Hutchinson Cancer Research Center (FHCRC) and MD Anderson Cancer Center (MDACC). Patients who died, received anticoagulation, or did not engraft platelets by day 30 were excluded. Primary outcomes were defined as overall VTE and pulmonary embolism ± lower-extremity deep venous thromboembolism (PE/LE-DVT) by day 180. Covariates were weighted according to the original model, except that grade 2-4 GVHD was substituted for grade 3-4. Discrimination and calibration were assessed. A total of 765 patients from FHCRC and 954 patients from MDACC were included. Incident VTE by day 180 was 5.1% at FHCRC and 6.8% at MDACC. The HIGH-2-LOW score had a c-statistic of 0.67 (0.59-0.75) for VTE and 0.75 (0.64-0.81) for PE/LE-DVT at FHCRC and 0.62 (0.55-0.70) for VTE and 0.70 (0.56-0.83) for PE/LE-DVT at MDACC. Twenty-five percent and 23% of patients were classified as high risk (2+ points) in the two cohorts, respectively. High versus low-risk was associated with odds ratio (OR) of 2.80 (1.46-5.38) for VTE and 4.21 (1.82-9.77) for PE/LE-DVT at FHCRC and OR of 3.54 (2.12-5.91) for VTE and 6.82 (2.30-20.16) for PE-LE-DVT at MDACC. The HIGH-2-LOW RAM identified allogeneic HCT recipients at high risk for VTE in both validation cohorts. It can improve evidence-based decision-making for thromboprophylaxis post-transplant.

Reduction in Prevalence of Thrombotic Events in Sickle Cell Disease after Allogeneic Hematopoietic Transplantation

Thrombosis is a recognized complication in sickle cell disease (SCD). Allogeneic hematopoietic cell transplantation (allo-HCT) remains the only curative options for patients with severe SCD phenotypes. There is limited data describing the effects of allo-HCT on recurrent thrombotic events (venous and arterial events). We evaluated 31 patients with SCD who have undergone allo-HCT with a median follow up of 34.5 months (range:13-115) post-transplant. No patient continued anticoagulation or anti-platelets after allo-HCT. There was an absolute difference of 32% [95% CI=12.3-32.2, p=0.002] in the prevalence of venous thromboembolic (VTE) events before and after allo-HSCT. In addition, there was an absolute 38.5% [95% CI=10.63-45.96, p=0.006] difference in the number of ischemic cerebrovascular accidents (CVA) before and after allo-HSCT. Patients with severe SCD who undergo allo-HCT are less likely to develop recurrent thrombotic events OR 0.22 [95% CI=0.058 - 0.83, p=0.025] when compared to a control cohort of patients matched for age and genotype. Following curative therapy with allo-HCT, there is a reduction in recurrent arterial and venous thrombosis in patients with severe SCD phenotypes.

Risk Factors for Catheter-Related Thrombosis in Multiple Myeloma Patients Undergoing Autologous Stem Cell Transplantation

Background and Objectives: Cancer associated thrombosis (CAT) is a common complication of neoplasms. Multiple myeloma (MM) carries one of the highest risks of CAT, especially in the early phases of treatment. Autologous stem cell transplantation (ASCT) as the standard of care in transplant-eligible patients with MM carries a risk of catheter-related thrombosis (CRT). The aim of this study was identification of the risk factors of CRT in MM patients undergoing ASCT in 2009–2019. Materials and Methods: We retrospectively analyzed patients with MM undergoing ASCT. Each patient had central venous catheter (CVC) insertion before the procedure. The clinical symptoms of CRT (edema, redness, pain in the CVC insertion area) were confirmed with Doppler ultrasound examination. We examined the impacts of four groups of factors on CRT development: (1) patient-related: age, gender, Body Mass Index (BMI), obesity, Charlson comorbidity index, hematopoietic stem cell transplantation comorbidity index, renal insufficiency, and previous thrombotic history; (2) disease-related: monoclonal protein type, stage of the disease according to Salmon–Durie and International Staging System, number of prior therapy lines, and MM response before ASCT; (3) treatment-related: melphalan dose, transplant-related complications, and duration of post-ASCT neutropenia; (4) CVC-related: location, time from placement to removal. Results: Symptomatic CRT was present in 2.5% (7/276) of patients. Univariate analysis showed an increased risk of CRT in patients with a catheter-related infection (OR 2.4, 95% CI; 1.109–5.19, p = 0.026), previous thrombotic episode (OR 2.49, 95% CI; 1.15–5.39, p = 0.021), previous thrombotic episode on initial myeloma treatment (OR 2.75, 95% CI; 1.15–6.53, p = 0.022), and gastrointestinal complications of ASCT such as vomiting and diarrhea (OR 3.87, 95% CI; 1.57–9.53, p = 0.003). In multivariate analysis, noninfectious complications were associated with higher CRT incidence (OR 2.75, 95% CI; 1.10–6.19, p = 0.031). Conclusions: The incidence of symptomatic CRT in ASCT in MM was relatively low. Previous thrombotic events, especially during the induction of myeloma treatment, increased CRT risk during ASCT. Dehydration following gastrointestinal complications may predispose to higher CRT incidence.

Impact of anticoagulation on recurrent thrombosis and bleeding after hematopoietic cell transplantation

History of venous thromboembolism (VTE) is prevalent among patients undergoing hematopoietic cell transplantation (HCT). Management of anticoagulation is particularly challenging as most patients will have chemotherapy-induced thrombocytopenia while awaiting engraftment post-HCT. We conducted a retrospective study of autologous and allogeneic HCT recipients with prior VTE from 2006-2015 to 1) compare anticoagulant strategies on short-term VTE recurrence and bleeding and 2) assess predictors for VTE recurrence beyond 30 days. Patients with VTE were allocated to two cohorts based on anticoagulant strategy at thrombocytopenia onset and underwent inverse probability weighting to assess primary outcomes of VTE recurrence and bleeding within 30 days post-HCT. Subsequently, multivariable logistic regression model was used to assess the association of 100-day VTE recurrence by the HIGH-2-LOW VTE risk assessment score and whether patients resumed anticoagulation at platelet recovery. Thirteen percent of recipients had VTE prior to HCT; of those meeting inclusion criteria, 227 continued anticoagulation and 113 temporarily discontinued it. Anticoagulant strategy was not significantly associated with decreased risk of VTE recurrence within 30 days (3% vs 4%, p = 0.61); however, risk of overall bleeding was non-significantly higher in those who continued vs discontinued anticoagulation (41% vs 31%, p = 0.08). In a subgroup of 250 allogeneic HCT patients, every one-point increase of HIGH-2-LOW score was significantly associated with VTE recurrence at 100 days (OR 1.57 [95% CI 1.10-2.23]), while anticoagulation resumption upon platelet engraftment was associated with lower recurrent risk (OR 0.48 [0.20-1.14]). Temporarily withholding anticoagulation during thrombocytopenia may optimize risk-benefit tradeoffs, though additional strategies are essential to prevent VTE recurrence after hematopoietic recovery.

HIGH-2-LOW risk model to predict venous thromboembolism in allogeneic transplant patients after platelet engraftment

Venous thromboembolism (VTE) after allogeneic hematopoietic cell transplantation (HCT) is a significant treatment-associated complication, although optimal timing of thromboprophylaxis remains uncertain when weighing concurrent risks of bleeding. We aimed to derive and internally validate a risk assessment model (RAM) using patients who underwent first allogeneic HCT from 2006 through 2015 (n = 1703). Index date was defined as the 30th day after transplant, at which point we estimated >75% of patients would have achieved platelet engraftment >50 × 109/L. Stepwise logistic regression modeling was used for model development, and internal validation was achieved by fitting a logistic regression model with 1000 bootstrapped resamples to estimate the optimism-corrected c-statistic. The final RAM, "HIGH-2-LOW," included 7 predictors obtained at 30 days after transplant: History of catheter-related deep venous thrombosis (DVT), Inpatient at day 30, Graft-versus-host disease grade 3 to 4, History of pulmonary embolism or lower-extremity DVT, Lymphoma diagnosis, Obesity with body mass index ≥35 kg/m2, and White blood cell count ≥11 × 109/L. Approximately 16% of patients were stratified as high risk, with incident VTE rate of 10.3% at 100 days compared with 1.5% for those at low risk. VTE odds ratios at 100 days were 5.87 (95% confidence interval [CI], 2.98-11.57) and 2.71 (95% CI, 1.38-5.35) in the high- and intermediate-risk vs low-risk groups, respectively. HIGH-2-LOW model serves as a novel and potentially clinically meaningful tool to identify high-risk allogeneic HCT patients who may benefit from early thromboprophylaxis after platelet engraftment.

Outcomes of symptomatic venous thromboembolism after haploidentical donor hematopoietic stem cell transplantation and comparison with human leukocyte antigen-identical sibling transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is regarded as a curative therapy for majority of hematologic malignancies and some non-malignant hematologic diseases. Venous thromboembolism (VTE) has become increasingly recognized as a severe complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT).

OBJECTIVES

To show the characteristics of VTE after haploidentical donor hematopoietic stem cell transplantation (HID-HSCT) and make comparisons with matched related donor HSCT (MRD-HSCT).

PATIENTS/METHODS

A retrospective nested case-control study design was used, cases with VTE and matched controls were selected, with 3534 patients underwent HID-HSCT and 1289 underwent MRD-HSCT.

RESULTS

During follow-up, 114 patients with VTE were identified. The incidence of VTE in HID-HSCT group was similar to that of MRD-HSCT group (2.4% versus 2.3%, P = 0.92). In HID-HSCT group, VTE occurred at a median time of 92.5 days, which was earlier than MRD-HSCT group (243.5 days). For HID-HSCT, advanced disease status, cardiovascular risk factors, acute graft-versus-host disease (aGVHD), and relapse were the independent risk factors for VTE. For MRD-HSCT, cardiovascular risk factors, aGVHD, and relapse were associated with VTE. Overall survival (OS) of patients following HID-HSCT and MRD-HSCT were similar, but the OS in patients with VTE was significantly lower than patients without VTE.

CONCLUSIONS

There was no statistical difference in the incidence of VTE after HID-HSCT compared with MRD-HSCT. The development of VTE adversely impacted the OS after allo-HSCT.

Catheter-Related Thrombosis in Patients with Lymphoma or Myeloma Undergoing Autologous Stem Cell Transplantation

Catheter-related thrombosis (CRT) occurs frequently during autologous hematopoietic cell transplantation (AHCT) and data regarding the incidence, risk factors, and management are understudied. We evaluated 789 consecutive patients with lymphoma and myeloma that underwent AHCT over 10 years (2006 to 2016) and detected the incidence of CRT was 6.3%; only 32% of CRT were symptomatic. The majority occurred within 100 days of AHCT (86%) and median time from tunneled line placement to CRT was 44 days (range, 11 to 89 days). Outcomes of these 50 patients with CRT were compared with age- and disease-matched AHCT control subjects to identify risk factors. History of prior venous thromboembolism (VTE) (20.9% versus 7.0%, P = .02) was the only significant risk factor. Treatment with low-molecular-weight heparin was tolerated with rare minor bleeding (4%), although CRT recurrence or extension (10%) and subsequent VTE (12%) were common. CRT did not impact on nonrelapse mortality or risk of relapse; 2-year progression-free survival was 55% in CRT cases versus 54% in control subjects (P = .42). CRT appears to be common in patients with lymphoma and myeloma undergoing AHCT and significantly contributes to morbidity. Further study to determine mitigating strategies and modify risk factors for CRT is warranted.

Venous Thromboembolism in Pediatric Hematopoietic Cell Transplant: A Multicenter Cohort Study

Hematopoietic cell transplant (HCT) is associated with a proinflammatory, procoagulant environment that places recipients at increased risk of venous thromboembolism (VTE). Although the incidence of VTE in adult HCT recipients has been extensively studied, similar data for children are lacking. We conducted a multicenter retrospective study to analyze the prevalence of VTE and associated risk factors in a large cohort of patients who underwent HCT at tertiary care US children's hospitals. The Pediatric Health Information System database, a large administrative database that contains clinical and resource utilization data from 49 freestanding children's hospitals in the United States, was used to extract data. International Classification of Diseases, Ninth Revision, Clinical Modification codes were used to identify HCT recipients, VTE events, post-HCT complications, and associated risk factors up to 1 year post-transplant. Data on patients who received HCT from January 2010 through September 2014 were collected. A total of 4158 unique patients mean ± standard deviation age at transplant admit, 8.8 ± 6.5 years; range, birth to 33.4 years) were identified. After HCT 290 subjects (6.9%) developed VTE. VTE prevalence was greater in patients aged ≥ 13 versus <13 years (8.54% versus 6.33%; P = .01) and in recipients of allogeneic versus autologous grafts (7.7% versus 5%; P ≤ .01). VTE was associated with prolonged median duration of hospitalization (81 versus 54 days; P ≤.01) and increased 1-year mortality (13.9% versus 5.9%; P ≤ .01). Infections and presence of any graft-versus-host disease (GVHD) were significantly associated with VTE occurrence in recipients of allogenic grafts. Prevalence of VTE in patients who underwent HCT at pediatric tertiary care hospitals is about 7%. Age ≥ 13 years and allogeneic grafts were significant pre-HCT VTE risk factors, with GVHD and infections seen more frequently in patients with VTE.