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Prophylactic tranexamic acid in patients with hematologic malignancy: a placebo controlled, randomized clinical trial
Gernsheimer TB, Brown SP, Triulzi DJ, Key NS, El Kassar N, Herren H, Poston JN, Boyiadzis M, Reeves BN, Selukar S, et al
Blood. 2022
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Editor's Choice
Abstract
Evidence of effectiveness of prophylactic use of tranexamic acid (TXA) in thrombocytopenia is lacking. To determine whether TXA safely reduces bleeding incidence in patients undergoing treatment for hematologic malignancies, a randomized double blind clinical trial was conducted June 2016 through June 2020. Of 3120 screened adults 356 patients were eligible and enrolled, and 337 patients (mean age, 53.9; 141 (41.8%) women), randomized to 1,300mg TXA orally or 1,000mg TXA intravenously (n=168) versus placebo (n=169) thrice daily for maximum 30 days. 330 patients were activated when their platelet counts fell below 30,000/µl; 279 (83%) had complete outcome ascertainment. WHO grade 2 or higher bleeding was observed in the 30 days following activation in 50.3% (73/145) and 54.2% (78/144) of patients in the TXA and placebo groups, adjusted odds ratio: 0.83 (95%CI:0.50,1.34; p=0.44). There was no statistically significant difference in mean number of platelet transfusions (0.1;95%CI:-1.9,2.0), mean days alive without grade 2 or higher bleeding (0.8;95%CI:-0.4,2.0), thrombotic events (6/163 (3.7%) TXA, 9/163 (5.5%) placebo), or deaths due to serious bleeding. Most common adverse events were: diarrhea [(116/164 (70.7%) TXA and 114/163 (69.9%) placebo)]; febrile neutropenia [111/164 (67.7%) TXA, 105/163 (64.4%) placebo]; fatigue [106/164 (64.6%) TXA, 109/163 (66.9%) placebo]; and nausea [104/164 (63.4%) TXA, 97/163 (59.5%) placebo]. Among patients with hematologic malignancy undergoing chemotherapy or hematopoietic stem cell transplantation, prophylactic treatment with tranexamic acid compared with placebo did not significantly reduce the risk of WHO grade 2 or higher bleeding. Trial Registration: Clinicaltrials.gov Identifier: NCT02578901.
PICO Summary
Population
Patients who were thrombocytopenic due to primary bone marrow disorders or chemotherapy, immunotherapy, and/or radiation therapy (n= 337).
Intervention
Tranexamic acid (TXA) orally or intravenously (n= 168).
Comparison
Placebo (n= 169).
Outcome
The primary outcome of WHO grade 2 or higher bleeding during the first 30 days after activation was observed for 73 out of 145 (50.3%) and 78 out of 144 (54.2%) patients in the TXA and placebo groups, respectively. There was no statistically significant difference in mean number of platelet transfusions (0.1), mean days alive without grade 2 or higher bleeding (0.8), thrombotic events (6/163 (3.7%) TXA, 9/163 (5.5%) placebo), or deaths due to serious bleeding.
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Comparison of early mortality between leukapheresis and non-leukapheresis in adult acute myeloid leukemia patients with hyperleukocytosis: a systematic review and meta-analysis
Rinaldi I, Sutandyo N, Winston K
Hematology (Amsterdam, Netherlands). 2022;27(1):141-149
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Editor's Choice
Abstract
OBJECTIVES One of the treatment modalities that can be used for hyperleukocytosis is leukapheresis. However, the result of studies showing the benefit of early mortality through the use of leukapheresis versus no leukapheresis is still inconclusive. Hence, we aimed to conduct a systematic review with meta-analysis to determine the effect of leukapheresis on early mortality in AML patients with hyperleukocytosis. METHODS We conducted a literature search on five databases (PubMed, EBSCOhost, Scopus, Clinicalkey, and JSTOR) up to October 2021 for studies comparing early mortality outcomes between hyperleukocytosis AML patients treated with leukapheresis versus no leukapheresis. Summary odds ratios (OR) and 95% confidence intervals (CI) were calculated using random-effects models. Heterogeneity tests were presented in I(2) value and publication bias was analyzed using a funnel plot. RESULTS Eleven retrospective cohort studies were eligible based on the inclusion and exclusion criteria. Pooled analysis showed that there was no significant difference in early mortality between patients receiving leukapheresis and not receiving leukapheresis in studies using hyperleukocytosis cutoff of 95,000/mm(3) or 100,000/mm(3) (OR: 1.17; 95% CI: 0.74-1.86; p: 0.50; I(2): 0%). Similarly, studies using hyperleukocytosis cutoff of 50,000/mm(3) also showed no benefits of early mortality (OR: 0.67; 95% CI: 0.43-1.05; p: 0.08; I(2): 0%). Most of the studies used had a moderate risk of bias due to being observational studies. Funnel plot showed an indication of publication bias on studies using hyperleukocytosis cutoff of ≥50,000/mm(3). CONCLUSION The use of leukapheresis does not provide early mortality benefit in adult AML patients with hyperleukocytosis.
PICO Summary
Population
Adult acute myeloid leukemia patients (11 studies, n= 1,407).
Intervention
Leukapheresis intervention (n= 1,090).
Comparison
Not receiving leukapheresis (n= 317).
Outcome
Pooled analysis showed that there was no significant difference in early mortality between patients receiving leukapheresis and not receiving leukapheresis in studies using hyperleukocytosis cutoff of 95,000/mm3 or 100,000/mm3. Studies using hyperleukocytosis cutoff of 50,000/mm3 showed no benefits of early mortality.
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Oral eltrombopag versus subcutaneous recombinant human thrombopoietin for promoting platelet engraftment after allogeneic stem cell transplantation: A PROSPECTIVE, NON-INFERIORITY, RANDOMIZED CONTROLLED TRIAL
Wen B, Zhang X, Chen S, Fan J, Yang S, Cai Y, Wang P, Zhang Q, Gu Q, Du X
Hematological oncology. 2022
Abstract
Delayed platelet engraftment (DPE) is associated with poor survival and increased transplantation-related mortality after allogeneic haematopoietic stem cell transplantation (allo-HSCT). Therefore, treatments are needed to improve platelet engraftment and prevent DPE. We performed a phase 3, non-inferior, randomized controlled study of eltrombopag or recombinant human thrombopoietin (rhTPO) to promot platelet engraftment after allo-HSCT. Candidates for allo-HSCT were randomly assigned to receive oral eltrombopag (50mg daily) or subcutaneous rhTPO (15000U daily ) from the first-day post-transplantation. The primary endpoint was the cumulative numbers of platelet engraftment (platelet recovery ≥ 20 × 10(9) /L, without transfusion, for seven consecutive days) on day 60 after transplantation. We performed intention-to-treat analyses with a non-inferior margin of -15%. A total of 92 participants underwent randomization. 44 and 48 patients were randomized to the eltrombopag and rhTPO groups, respectively. The median duration of follow-up was 360 days (range: 12-960 days). The cumulative incidence of platelet engraftment on day 60 after transplantation in eltrombopag group was 86.4% (38/44) compared with 85.4% (41/48) in the rhTPO group (absolute risk difference [ARD] 1%, one-sided lower limit of 95% confidence interval [CI] -13.28%, P(non-inferirioty) =0.014). The rate of DPE in the eltrombopag group was 6.8% (3/44) compared with 12.5% (6/ 48) in the rhTPO group (ARD -5.7%, one-sided higher limit of 95% CI 6.28%, P(non-inferirioty) =0.063). Approximately, 3/4 of non-haematologic adverse events were not observed in the eltrombopag group but three patients (3/48, 6%) experienecd them in the rhTPO group. In addtion, platelet transfusions unite from day 0 to day 21, or from day 22 to day 60, progression-free survival, overall survival were not significantly different between both groups. Eltrombopag was non-inferior to rhTPO in promoting platelet engraftment post allo-HSCT for patients with haematological malignancy. Oral eltrombopag was more convenient for patients than subcutaneous rhTPO (NCT03515096). This article is protected by copyright. All rights reserved.
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Do liberal thresholds for red cell transfusion result in improved quality of life for patients undergoing intensive chemotherapy for acute myeloid leukemia? A randomized cross over feasibility study
Morton S, Sekhar M, Smethurst H, Mora A, Hodge RL, Hudson CL, Parsons J, Hopkins V, Stanworth SJ
Haematologica. 2022
Abstract
Not available.
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Intravenous Iron Supplementation for the Treatment of Chemotherapy-Induced Anemia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Buchrits S, Itzhaki O, Avni T, Raanani P, Gafter-Gvili A
Journal of clinical medicine. 2022;11(14)
Abstract
BACKGROUND The pathophysiology of cancer-related anemia is multifactorial, including that of chemotherapy-induced anemia (CIA). The guidelines are not consistent in their approach to the use of intravenous (IV) iron in patients with cancer as part of the clinical practice. MATERIALS AND METHODS All randomized controlled trials that compared IV iron with either no iron or iron taken orally for the treatment of CIA were included. We excluded trials if erythropoiesis-stimulating agents (ESAs) were used. The primary outcome was the percentage of patients requiring a red blood cell (RBC) transfusion during the study period. The secondary outcomes included the hematopoietic response (an increase in the Hb level by more than 1 g/dL or an increase above 11 g/dL), the iron parameters and adverse events. For the dichotomous data, risk ratios (RRs) with 95% confidence intervals (Cis) were estimated and pooled. For the continuous data, the mean differences were calculated. A fixed effect model was used, except in the event of significant heterogeneity between the trials (p < 0.10; I(2) > 40%), in which we used a random effects model. RESULTS A total of 8 trials published between January 1990 and July 2021 that randomized 1015 patients fulfilled the inclusion criteria. Of these, 553 patients were randomized to IV iron and were compared with 271 patients randomized to oral iron and 191 to no iron. IV iron decreased the percentage of patients requiring a blood transfusion compared with oral iron (RR 0.72; 95% CI 0.55-0.95) with a number needed to treat of 20 (95% CI 11-100). IV iron increased the hematopoietic response (RR 1.23; 95% CI 1.01-1.5). There was no difference with respect to the risk of adverse events (RR 0.97; 95% CI 0.88-1.07; 8 trials) or severe adverse events (RR 1.09; 95% CI 0.76-1.57; 8 trials). CONCLUSIONS IV iron resulted in a decrease in the need for RBC transfusions, with no difference in adverse events in patients with CIA. IV iron for the treatment of CIA should be considered in clinical practice.
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Systemic therapy of necrobiotic xanthogranuloma: a systematic review
Steinhelfer L, Kühnel T, Jägle H, Mayer S, Karrer S, Haubner F, Schreml S
Orphanet journal of rare diseases. 2022;17(1):132
Abstract
BACKGROUND Even though a plethora of systemic therapies have been proposed for necrobiotic xanthogranuloma (NXG), there is no systematic review on this topic in literature. OBJECTIVE To review all existing literature on the systemic therapy of NXG in order to identify the most effective therapies. METHODS All reported papers in the literature were screened for systemic treatments of NXG. Papers without proper description of the therapies, papers describing topical therapy, and articles without assessment of effectiveness were excluded. Subsequently, we analyzed 79 papers and a total of 175 cases. RESULTS The most effective treatments for NXG are intravenous immunoglobulins (IVIG), corticosteroids, and combination therapies including corticosteroids. CONCLUSIONS Corticosteroids and IVIG should therefore be considered first-line treatments in patients with NXG.
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Outcomes and Clinical Characteristics of Intracranial Hemorrhage in Patients with Hematological Malignancies: A Systematic Literature Review
Raghavan A, Wright CH, Wright JM, Jensen K, Malloy P, Elder T, Burant C, Sajatovic M, Hoffer A
World Neurosurg. 2020
Abstract
BACKGROUND Many clinical and demographic factors can influence survival of patients with hematological malignancies who have intracranial hemorrhages. Understanding the influence of these factors on patient survival can guide treatment decisions and may inform prognostic discussions. We conducted a systematic literature review to determine survival of patients with intracranial hemorrhages and concomitant hematologic malignancy. METHODS A systematic literature review was conducted and followed Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Pubmed/MEDLINE, Web of Science, Ovid, SCOPUS, and Embase databases were queried with the following terms: ("intracranial hemorrhages" OR "brain hemorrhage" OR "cerebral hemorrhage" OR "subdural hematoma" OR "epidural hematoma" OR "intraparenchymal hemorrhage") AND ("Hematologic Neoplasms" OR "Myeloproliferative Disorders" OR "Myelofibrosis" OR "Essential thrombocythemia" OR "Leukemia"). Abstracts and articles were screened according to inclusion and exclusion criteria that were determined a priori. RESULTS Literature review yielded 975 abstracts from which a total of 68 full-text articles were reviewed. 12 articles capturing 634 unique patients were included in the final qualitative analysis. Median overall survival for all patients ranged from 20 days - 1.5 months while median overall survival for the subset of patients having ICH within 10 days of diagnosis of hematological malignancy was 5 days. Intraparenchymal hemorrhages, multiple foci of hemorrhage, transfusion-resistant low platelet counts, leukocytosis, low GCS scores at presentation, and ICH early in treatment course were associated with worse outcomes. CONCLUSIONS Survival for patients with hematological malignancies and concomitant ICHs remains poor. Early detection, recognition of poor prognostic and correction of hematological abnormalities appears essential to prevention and treatment of ICHs in this patient population.
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Exploring the components of bleeding outcomes in transfusion trials for patients with hematologic malignancy
Balitsky AK, Liu Y, Van der Meer PF, Heddle NM, Arnold DM
Transfusion. 2020
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Editor's Choice
Abstract
Clinically significant bleeding in patients with hematologic malignancies is a heterogeneous composite outcome currently defined as World Health Organization (WHO) bleeding Grades 2, 3, and 4. However, the clinical significance of some minor bleeds categorized as WHO Grades 1 and 2 remains controversial. We analyzed the number and frequency of individual signs and symptoms of WHO Grades 1 and 2 bleeds and explored their association with more severe incident bleeds graded as WHO Grades 3 and 4. STUDY DESIGN AND METHODS We aggregated daily bleeding assessment data from three randomized controlled trials conducted in patients with hematologic malignancies that used bleeding as an outcome. Cox proportional hazard regression analysis was used to identify signs and symptoms categorized as WHO Grades 1 and 2 bleeds that were associated with more severe bleeds (Grades 3 and 4). RESULTS We collected data from 315 patients (n = 5476 daily bleeding assessments; 3383 [61.8%] with a bleed documented). A total of 98.3% (3326/3383) were Grade 1 and 2 bleeds and 1.7% (57/3383) were Grades 3 and 4. Grade 1 and 2 bleeds were composed of 20 different bleeding signs and symptoms. Hematuria (hazard ratio, 16.1; 95% confidence interval, 4.4-59.2; P < .0001) was associated with incident Grade 3 or 4 bleeds. CONCLUSION In patients with hematologic malignancy, only hematuria (microscopic and/or macroscopic) was associated with more severe incident bleeds. This findings require validation in independent data sets.
PICO Summary
Population
Patients with haematologic malignancies and chemotherapy-induced thrombocytopenia (3 randomised controlled trials (RCTs), n= 315).
Intervention
Less severe bleeds (WHO Grades 1 and 2).
Comparison
More severe bleeds (WHO Grades 3 and 4).
Outcome
The total data aggregated from the 3 RCTs was 5,476 daily bleeding assessments, 61.8% with a bleed documented. A total of 98.3% were Grade 1 and 2 bleeds and 1.7% were Grades 3 and 4. Grade 1 and 2 bleeds were composed of 20 different bleeding signs and symptoms. Haematuria was associated with incident Grade 3 or 4 bleeds. In patients with haematologic malignancy, only haematuria was associated with more severe bleeds.
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A Multicenter Cross-Sectional Study and Systematic Review of Necrobiotic Xanthogranuloma With Proposed Diagnostic Criteria
Nelson CA, Zhong CS, Hashemi DA, Ashchyan HJ, Brown-Joel Z, Noe MH, Imadojemu S, Micheletti RG, Vleugels RA, Wanat KA, et al
JAMA dermatology. 2020
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Abstract
Importance: Necrobiotic xanthogranuloma (NXG) is a non-Langerhans cell histiocytosis classically associated with paraproteinemia attributable to plasma-cell dyscrasias or lymphoproliferative disorders. Despite the morbidity of NXG, the literature is limited to case reports and small studies, and diagnostic criteria are lacking. Objective: To evaluate the characteristics of NXG and propose diagnostic criteria. Design, Setting, and Participants: This multicenter cross-sectional study was conducted at tertiary academic referral centers and followed by a systematic review and a consensus exercise. The multicenter cohort included patients with NXG diagnosed at the Brigham and Women's and Massachusetts General Hospitals (2000-2018), the University of Iowa Hospitals and Clinics (2000-2018), and the University of Pennsylvania Health System (2008-2018). The systematic review was conducted in 2018 and included patients with NXG identified in the Cochrane, Ovid EMBASE, PubMed, and Web of Science databases. The consensus exercise was conducted by 8 board-certified dermatologists to identify diagnostic criteria. Main Outcomes and Measures: Demographic factors, comorbidities, clinical features, and treatment response. Results: Of 235 included patients with NXG (34 from the multicenter cohort and 201 from the systematic review results), the mean (SD) age at presentation was 61.6 (14.2) years; 147 (62.6%) were female. Paraproteinemia was detected in 193 patients (82.1%), most often IgG-kappa (117 patients [50.0%]). A malignant condition was detected in 59 patients (25.1%), most often multiple myeloma (33 patients [14.0%]). The overall rate of paraproteinemia and/or a malignant condition was 83.8% (197 patients). In the multicenter cohort, evolution of paraproteinemia into multiple myeloma was observed up to 5.7 years (median [range], 2.4 [0.1-5.7] years) after NXG presentation. Cutaneous lesions consisted of papules, plaques, and/or nodules, typically yellow or orange in color (113 of 187 [60.4%]) with a periorbital distribution (130 of 219 [59.3%]). The eye was the leading site of extracutaneous involvement (34 of 235 [14.5%]). In the multicenter cohort, intravenous immunoglobulin had the best treatment response rate (9 of 9 patients [100%]), followed by antimalarial drugs (4 of 5 patients [80%]), intralesional triamcinolone (6 of 8 patients [75%]), surgery (3 of 4 patients [75%]), chemotherapy (8 of 12 patients [67%]), and lenalidomide or thalidomide (5 of 8 patients [63%]). The consensus exercise yielded 2 major criteria, which were (1) clinical and (2) histopathological features consistent with NXG, and 2 minor criteria, consisting of (1) paraproteinemia, plasma-cell dyscrasia, and/or other associated lymphoproliferative disorder and (2) periorbital distribution of cutaneous lesions. In the absence of foreign body, infection, or another identifiable cause, fulfillment of both major and at least 1 minor criterion were proposed to establish the diagnosis of NXG. Conclusions and Relevance: Necrobiotic xanthogranuloma is a multisystem disorder associated with paraproteinemia and malignant conditions. The proposed diagnostic criteria may advance clinical research and should be validated.
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Prophylaxis of thromboembolism during therapy with asparaginase in adults with acute lymphoblastic leukaemia
Rank CU, Lynggaard LS, Als-Nielsen B, Stock W, Toft N, Nielsen OJ, Frandsen TL, Tuckuviene R, Schmiegelow K
The Cochrane database of systematic reviews. 2020;10:Cd013399
Abstract
BACKGROUND The risk of venous thromboembolism is increased in adults and enhanced by asparaginase-based chemotherapy, and venous thromboembolism introduces a secondary risk of treatment delay and premature discontinuation of key anti-leukaemic agents, potentially compromising survival. Yet, the trade-off between benefits and harms of primary thromboprophylaxis in adults with acute lymphoblastic leukaemia (ALL) treated according to asparaginase-based regimens is uncertain. OBJECTIVES The primary objectives were to assess the benefits and harms of primary thromboprophylaxis for first-time symptomatic venous thromboembolism in adults with ALL receiving asparaginase-based therapy compared with placebo or no thromboprophylaxis. The secondary objectives were to compare the benefits and harms of different groups of primary systemic thromboprophylaxis by stratifying the main results per type of drug (heparins, vitamin K antagonists, synthetic pentasaccharides, parenteral direct thrombin inhibitors, direct oral anticoagulants, and blood-derived products for antithrombin substitution). SEARCH METHODS We conducted a comprehensive literature search on 02 June 2020, with no language restrictions, including (1) electronic searches of Pubmed/MEDLINE; Embase/Ovid; Scopus/Elsevier; Web of Science Core Collection/Clarivate Analytics; and Cochrane Central Register of Controlled Trials (CENTRAL) and (2) handsearches of (i) reference lists of identified studies and related reviews; (ii) clinical trials registries (ClinicalTrials.gov registry; the International Standard Randomized Controlled Trial Number (ISRCTN) registry; the World Health Organisation's International Clinical Trials Registry Platform (ICTRP); and pharmaceutical manufacturers of asparaginase including Servier, Takeda, Jazz Pharmaceuticals, Ohara Pharmaceuticals, and Kyowa Pharmaceuticals), and (iii) conference proceedings (from the annual meetings of the American Society of Hematology (ASH); the European Haematology Association (EHA); the American Society of Clinical Oncology (ASCO); and the International Society on Thrombosis and Haemostasis (ISTH)). We conducted all searches from 1970 (the time of introduction of asparaginase in ALL treatment). We contacted the authors of relevant studies to identify any unpublished material, missing data, or information regarding ongoing studies. SELECTION CRITERIA Randomised controlled trials (RCTs); including quasi-randomised, controlled clinical, cross-over, and cluster-randomised trial designs) comparing any parenteral/oral preemptive anticoagulant or mechanical intervention with placebo or no thromboprophylaxis, or comparing two different pre-emptive anticoagulant interventions in adults aged at least 18 years with ALL treated according to asparaginase-based chemotherapy regimens. For the description of harms, non-randomised observational studies with a control group were eligible for inclusion. DATA COLLECTION AND ANALYSIS Using a standardised data collection form, two review authors independently screened and selected studies, extracted data, assessed risk of bias for each outcome using standardised tools (RoB 2.0 tool for RCTs and ROBINS-I tool for non-randomised studies) and the certainty of evidence for each outcome using the GRADE approach. Primary outcomes included first-time symptomatic venous thromboembolism, all-cause mortality, and major bleeding. Secondary outcomes included asymptomatic venous thromboembolism, venous thromboembolism-related mortality, adverse events (i.e. clinically relevant non-major bleeding and heparin-induced thrombocytopenia for trials using heparins), and quality of life. Analyses were performed according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions. For non-randomised studies, we evaluated all studies (including studies judged to be at critical risk of bias in at least one of the ROBINS-I domains) in a sensitivity analysis exploring confounding. MAIN RESULTS We identified 23 non-randomised studies that met the inclusion criteria of this review, of which 10 studies provided no outcome data for adults with ALL. We included the remaining 13 studies in the 'Risk of bias' assessment, in which we identified invalid control group definition in two studies and judged outcomes of nine studies to be at critical risk of bias in at least one of the ROBINS-I domains and outcomes of two studies at serious risk of bias. We did not assess the benefits of thromboprophylaxis, as no RCTs were included. In the main descriptive analysis of harms, we included two retrospective non-randomised studies with outcomes judged to be at serious risk of bias. One study evaluated antithrombin concentrates compared to no antithrombin concentrates. We are uncertain whether antithrombin concentrates have an effect on all-cause mortality (risk ratio (RR) 0.55, 95% confidence interval (CI) 0.26 to 1.19 (intention-to-treat analysis); one study, 40 participants; very low certainty of evidence). We are uncertain whether antithrombin concentrates have an effect on venous thromboembolism-related mortality (RR 0.10, 95% CI 0.01 to 1.94 (intention-to-treat analysis); one study, 40 participants; very low certainty of evidence). We do not know whether antithrombin concentrates have an effect on major bleeding, clinically relevant non-major bleeding, and quality of life in adults with ALL treated with asparaginase-based chemotherapy, as data were insufficient. The remaining study (224 participants) evaluated prophylaxis with low-molecular-weight heparin versus no prophylaxis. However, this study reported insufficient data regarding harms including all-cause mortality, major bleeding, venous thromboembolism-related mortality, clinically relevant non-major bleeding, heparin-induced thrombocytopenia, and quality of life. In the sensitivity analysis of harms, exploring the effect of confounding, we also included nine non-randomised studies with outcomes judged to be at critical risk of bias primarily due to uncontrolled confounding. Three studies (179 participants) evaluated the effect of antithrombin concentrates and six studies (1224 participants) evaluated the effect of prophylaxis with different types of heparins. When analysing all-cause mortality; venous thromboembolism-related mortality; and major bleeding (studies of heparin only) including all studies with extractable outcomes for each comparison (antithrombin and low-molecular-weight heparin), we observed small study sizes; few events; wide CIs crossing the line of no effect; and substantial heterogeneity by visual inspection of the forest plots. Although the observed heterogeneity could arise through the inclusion of a small number of studies with differences in participants; interventions; and outcome assessments, the likelihood that bias due to uncontrolled confounding was the cause of heterogeneity is inevitable. Subgroup analyses were not possible due to insufficient data. AUTHORS' CONCLUSIONS We do not know from the currently available evidence, if thromboprophylaxis used for adults with ALL treated according to asparaginase-based regimens is associated with clinically appreciable benefits and acceptable harms. The existing research on this question is solely of non-randomised design, seriously to critically confounded, and underpowered with substantial imprecision. Any estimates of effect based on the existing insufficient evidence is very uncertain and is likely to change with future research.