Incidence and risk factors for postthrombotic syndrome in neonates and children in a single-center cohort study.

BACKGROUND: Postthrombotic syndrome (PTS) is a chronic condition following deep vein thrombosis (DVT) and is associated with pain, swelling, and restricted use of the affected limb. In pediatric age groups, its incidence and risk factors are not well-known. METHODS: This observational cohort study of all consecutive children (≤18 years) with DVT treated at the Emma Children's Hospital Amsterdam between January 2001 and January 2021 was conducted to identify incidence and risk factors for PTS in neonates aged ≤2 months and children aged >2 months. PTS was diagnosed using the modified Villalta scale. RESULTS: In total, 315 patients were included. The 20-year incidence of PTS was 20.0% in neonates and 40.0% in children. In neonates, involvement of ≥3 vessels (odds ratio [OR], 6.6; 95% CI, 1.6-26.4) and incomplete thrombus resolution (OR, 3.0; 95% CI, 1.1-8.0) were risk factors for PTS. In children, involvement of ≥3 vessels (OR, 6.2; 95% CI, 2.2-17.8), recurrent DVT (OR, 3.7; 95% CI, 1.3-10.3), and incomplete thrombus resolution (OR, 5.2; 95% CI, 1.6-17.0) were associated with PTS. Exercise ≥3 times/wk (OR, 0.4; 95% CI, 0.2-0.9), central venous catheter-related DVT (OR, 0.2; 95% CI, 0.1-0.5), and provoked DVT (OR, 0.4; 95% CI, 0.1-0.97) were protective factors for PTS. CONCLUSION: This study demonstrated a high incidence of pediatric PTS. Additionally, risk factors for PTS differed between neonates and children. These findings provide a basis for better prevention and management of PTS that may differ between neonates and children.

Apixaban overdose in children: case report and proposed management. A brief communication from the Pediatric and Neonatal Thrombosis and Hemostasis SSC of ISTH.

Background: Direct oral anticoagulants are commonly prescribed for adults and increasingly also for children requiring anticoagulation therapy. While household medications should not be accessible to children, accidental, and intentional overdoses occur. Key Clinical Question: How should apixaban overdose in children be managed?. Clinical Approach: We present a case of an accidental overdose with the factor Xa antagonist apixaban in a young child and propose an approach to the management of cases of apixaban overdose in children. Conclusion: Given the increasing use of direct oral anticoagulants, it is important to have an approach to the management of overdose of these medications.

Anticoagulation in pediatric cancer-associated venous thromboembolism: a subgroup analysis of EINSTEIN-Jr.

Anticoagulant treatment of pediatric cancer-associated venous thromboembolism (VTE) has not been prospectively evaluated. Management of anticoagulation for cancer-associated VTE is often challenged by drug interactions and treatment interruptions. A total of 56 of the 500 children (11.2%) with VTE who participated in the recent EINSTEIN-Jr randomized study had cancer (hematologic malignancy, 64.3%, solid malignant tumor, 35.7%). Children were allocated to either therapeutic-dose bodyweight-adjusted oral rivaroxaban (n=40) or standard anticoagulation with heparins, with or without vitamin K antagonists (n=16) and received a median of 30 concomitant medications. Based on sparse blood sampling at steady-state, pharmacokinetic (PK) parameters of rivaroxaban were derived using population PK modeling. During the 3 months of treatment, no recurrent VTE or major bleeding occurred (95% confidence interval, 0.0%-6.4%), and 3-month repeat imaging showed complete or partial vein recanalization in 20 and 24 of 52 evaluable children (38.5% and 46.2%, respectively). Anticoagulant treatment was interrupted 70 times in 26 (46.4%) children because of thrombocytopenia, invasive procedures, or adverse events, for a mean individual period of 5.8 days. Anticoagulant therapy was resumed in therapeutic doses and was not associated with thrombotic or bleeding complications. Rivaroxaban exposures were within the adult exposure range and similar to those observed in children with VTE who did not have cancer-associated VTE. Rivaroxaban and standard anticoagulants appeared safe and efficacious and were associated with reduced clot burden in most children with cancer-associated VTE, including those who had anticoagulant treatment interruptions. Rivaroxaban exposures were within the adult exposure range despite significant polypharmacy use. This trial was registered at www.clinicaltrials.gov as #NCT02234843.

American Society of Hematology 2018 Guidelines for management of venous thromboembolism: treatment of pediatric venous thromboembolism.

BACKGROUND: Despite an increasing incidence of venous thromboembolism (VTE) in pediatric patients in tertiary care settings, relatively few pediatric physicians have experience with antithrombotic interventions. OBJECTIVE: These guidelines of the American Society of Hematology (ASH), based on the best available evidence, are intended to support patients, clinicians, and other health care professionals in their decisions about management of pediatric VTE. METHODS: ASH formed a multidisciplinary guideline panel that included 2 patient representatives and was balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline-development process, including updating or performing systematic evidence reviews (up to April of 2017). The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The panel used the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, including GRADE Evidence-to-Decision frameworks, to assess evidence and make recommendations, which were subject to public comment. RESULTS: The panel agreed on 30 recommendations, covering symptomatic and asymptomatic deep vein thrombosis, with specific focus on management of central venous access device-associated VTE. The panel also addressed renal and portal vein thrombosis, cerebral sino venous thrombosis, and homozygous protein C deficiency. CONCLUSIONS: Although the panel offered many recommendations, additional research is required. Priorities include understanding the natural history of asymptomatic thrombosis, determining subgroup boundaries that enable risk stratification of children for escalation of treatment, and appropriate study of newer anticoagulant agents in children.

Thrombophilia testing in children: What and when should be tested?

Venous thrombosis (VTE) in children is gaining increased awareness and apart from underlying medical conditions, recently reported systematic reviews on pediatric VTE (70% provoked) have shown significant associations between thrombosis and presence of inherited thrombophilic risk factors (IT), such as protein C-, protein S- and antithrombin deficiency, mutations of factor 5 (F5: rs6025) and factor 2 (F2: rs1799963), even more pronounced when combined IT were involved. Although we have learned more about the pathophysiology of VTE with the increased discovery of IT evidence is still lacking as to whether IT influence the clinical outcome in pediatric VTE. It still remains controversial as to whether children with VTE or offspring from thrombosis-prone families benefit from IT screening. Thus, IT testing in children should be individualized. If the decision "pro screening" is discussed as an appropriate option in adolescents with unprovoked VTE and in children with a positive family history for VTE screening should be performed in a specialized coagulation unit for acquired or inherited and prothrombotic defects based on the individual population background. Apart from the laboratory assessment for the presence/absence of lupus anticoagulants and antiphospholipid antibodies screening should be performed beyond the acute VTE onset and after withdrawal of anticoagulant medication possibly influencing laboratory results.

Prevalence of Symptomatic and Asymptomatic Thrombosis in Pediatric Oncology Patients With Tunneled Central Venous Catheters.

BACKGROUND: Pediatric oncology patients with tunneled central venous catheters (CVCs) are at increased risk to develop venous thromboembolic events (VTEs), but the true prevalence of (a)symptomatic VTE is unknown. Aim of this study was to evaluate the prevalence of (a)symptomatic VTE in pediatric oncology patients with tunneled CVCs. PROCEDURE: All patients were included in the Aristocaths study: a randomized controlled multicenter trial investigating the prophylactic effect of 70% ethanol locks on CVC-associated bloodstream infections (CABSIs) were eligible for this study. We assessed the following outcomes: (i) symptomatic VTE and (ii) asymptomatic CVC-related VTE (using ultrasound [US]). Follow-up was 6 months, unless patients developed one of the following events: VTE, CABSI, CVC removal, or death. RESULTS: We included 305 patients (hematologic malignancy, n = 148; solid tumor, n = 157), median age 9 years (range, 1-18 years). Symptomatic VTE was detected in 8 of 305 patients (2.6%; 95% confidence interval [CI]: 1.1-5.1%), which was related to the CVC in three patients. Patients (185/305) were evaluated with US: 11 of 185 (5.9%; 95% CI: 3.0-10.4%) patients had asymptomatic CVC-related VTE. CONCLUSIONS: Prevalence of both symptomatic VTE and asymptomatic CVC-related VTE was low compared to other studies, which may be explained by the inclusion of patients with solid tumors, reduction of CABSI by ethanol, use of tunneled CVCs, and use of US.

Impact of persistent antiphospholipid antibodies on risk of incident symptomatic thromboembolism in children: a systematic review and meta-analysis.

The aim of this study was to estimate the impact of antiphospholipid (aPL) antibodies on the risk of incident thromboembolism (TE; arterial and venous) in children via meta-analysis of published observational studies. A systematic search of electronic databases (Medline, EMBASE, OVID, Web of Science, The Cochrane Library) for studies published from 1966 to 2010 was conducted using keywords in combination both as MeSH terms and text words. Two authors independently screened citations and those meeting the a priori defined inclusion criteria were retained. Data on year of publication, study design, country of origin, number of patients/controls, ethnicity, TE type, and frequency of recurrence were abstracted. Heterogeneity across studies was evaluated, and summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using either fixed-effects or random-effects models. Of 504, 16 pediatric studies met the inclusion criteria. In total 1403 patients and 1667 population-based controls ≤18 years were enrolled. No significant heterogeneity was discerned across studies, and no publication bias was detected. Thus, data from arterial and venous TE were analyzed together. In addition, meta-regression analysis did not reveal statistically significant differences between site of TE, age at first TE, country, or publication year. A statistically significant association with a first TE was demonstrated for persistent aPL antibodies, with an overall summary ORs/CI of 5.9/3.6-9.7 (arterial 6.6/3.5-12.4; deep vein thrombosis 4.9/2.2-10.9). The present meta-analysis indicates that detection of persistent aPL is clinically meaningful in children with, or at risk for, TE and underscores the importance of pediatric thrombophilia screening programs.

Thrombotic thrombocytopenic purpura in childhood.

Thrombotic thrombocytopenic purpura (TTP) is a rare disease, especially in childhood, and has a high mortality rate in the absence of appropriate treatment. It is characterised by microangiopathic haemolytic anaemia and consumptive thrombocytopenia. TTP may be difficult to distinguish from haemolytic uraemic syndrome (HUS) because of similar clinical manifestations and laboratory findings. In the past, TTP and HUS have often been considered to represent variable expressions of a single entity. Our increased understanding of the pathogenesis of TTP has in turn resulted in significant improvements in its treatment and outcomes. Several immunomodulating agents are currently being used with variable outcomes.

Impact of inherited thrombophilia on venous thromboembolism in children: a systematic review and meta-analysis of observational studies.

BACKGROUND: The aim of the present study was to estimate the impact of inherited thrombophilia (IT) on the risk of venous thromboembolism (VTE) onset and recurrence in children by a meta-analysis of published observational studies. METHODS AND RESULTS: A systematic search of electronic databases (Medline, EMBASE, OVID, Web of Science, The Cochrane Library) for studies published from 1970 to 2007 was conducted using key words in combination as both MeSH terms and text words. Citations were independently screened by 2 authors, and those meeting the inclusion criteria defined a priori were retained. Data on year of publication, study design, country of origin, number of patients/controls, ethnicity, VTE type, and frequency of recurrence were abstracted. Heterogeneity across studies was evaluated, and summary odds ratios and 95% CIs were calculated with both fixed-effects and random-effects models. Thirty-five of 50 studies met inclusion criteria. No significant heterogeneity was discerned across studies. Although >70% of patients had at least 1 clinical risk factor for VTE, a statistically significant association with VTE onset was demonstrated for each IT trait evaluated (and for combined IT traits), with summary odds ratios ranging from 2.63 (95% CI, 1.61 to 4.29) for the factor II variant to 9.44 (95% CI, 3.34 to 26.66) for antithrombin deficiency. Furthermore, a significant association with recurrent VTE was found for all IT traits except the factor V variant and elevated lipoprotein(a). CONCLUSIONS: The present meta-analysis indicates that detection of IT is clinically meaningful in children with, or at risk for, VTE and underscores the importance of pediatric thrombophilia screening programs.