Analysis of pediatric thrombotic patients in Turkey

Thromboembolism in Children

OBJECTIVE

To study pediatric patients who were diagnosed with thrombosis between January 2009 and March 2020.

METHODS

Patients were evaluated with respect to thrombophilic risk factors, localization of the thrombus, response to treatment, and recurrence rates during the last 11 y.

RESULTS

Among 84 patients, 59 (70%) had venous thrombosis and 20 (24%) had arterial thrombosis. The number of documented thrombosis amongst hospitalized children in authors' hospital has increased over the years. It has been observed that the annual incidence of thromboembolism has increased after 2014. Thirteen patients were recorded between 2009 and 2014 and 71 patients between 2015 and 2020 (until March 2020). Exact thrombosis localization could not be detected in 5 patients. The median age of patients was 8 ± 5.95 (range 0-18). Fourteen children (16.9%) had a history of familial thrombosis. Genetic and/or acquired risk factors were detected in 81 (96.4%) of the patients. Overall, 64 patients (76.1%) had acquired risk factors such as infection (20.2%), catheterization (13.1%), liver disease (11.9%), mastoiditis (8.3%), liver transplantation (6%), hypoxic-ischemic encephalopathy (4.8%), dehydration (3.6%), trauma (3.6%) and cancer (2.4%). As genetic risk factors, the most common genetic mutations were PAI-1 4G>5G, MTHFR C677T, and MTHFR A1298C mutations. Twenty-eight (41.2%) patients had at least one genetic thrombophilic mutation. At least one homozygous mutation in 37 patients (44%) and at least one heterozygous mutation in 55 patients (65.4%) were detected.

CONCLUSIONS

The annual incidence of thrombosis has increased over the years. Genetic predisposition and acquired risk factors play an important role in etiology, treatment, and follow-up in children with thromboembolism. Especially, genetic predisposition is common. Thrombophilic risk factors should be investigated and optimal therapeutic and prophylactic measures should be promptly taken in children with thrombosis.

Incidence and Management of Thromboembolism in Patients with Acute Leukemia

Thromboembolic events (TE) in childhood are relatively rare but, serious complications of acute leukemia. The aim was to define the incidence and risk factors of thrombosis in children with leukemias. The electronic files of pediatric denovo/relapsed acute leukemia patients aged below 18 years, treated between 2011 and 2021 were retrospectively evaluated for thrombotic attacks. Thirty out of 469 patients developed 35 thrombotic events. The median age at the time of the TE was 11.8 (2-17.6) years, and the median time from diagnosis to TE was 9 (0-58) months. The frequency of TE was found at 7.4% (n = 35/469). When catheter related (n = 13) events, superficial venous events (n = 10), and arterial central nervous system thrombosis (n = 1) were excluded, the frequency of TE was decreased to 2.3% (n = 11/469). Children older than 10 years old (13.8%; n = 21/152) had significantly higher thromboembolic events than the others (4.4%; n = 14/317) (p = 0.03). The majority of attacks were symptomatic 66% (n = 23/35). The most common complaints were local pain, swelling, and redness 52% (n = 12/23). The majority of attacks in patients with relapsed (75%; 6/8) and newly diagnosed acute lymphoblastic leukemia (40%; 10/25%) developed during the induction phase. Thrombosis recurred in 13.3% (n = 4/30) of cases more than once. Thrombotic attacks were successfully treated with low molecular weight heparin 60% (n = 21/35), and recombinant tissue plasminogen activator 17% (n = 6/35). None of the children were lost due to thrombosis. Thrombosis is an important complication during acute leukemia treatment. Successful results are obtained with early diagnosis and treatment attempts by creating awareness.

Thrombosis Prevention and Anticoagulation Management in the Pediatric Patient with Congenital Heart Disease

Thrombosis is one of the most frequent complications affecting children with congenital heart disease (CHD). Palliative and reparative cardiac surgeries are some of the main players contributing to the thrombosis risk in this patient population. Additional risk factors related to the CHD itself (e.g., cardiac dysfunction, arrhythmias, and polycythemia in cyanotic cardiac disorders) can contribute to thrombogenicity alone or combined with other factors. Thrombotic complications have been recognized as a significant cause of morbidity and mortality in this patient population. Here, we provide an overview of the pathophysiology and risk factors for thrombosis as well as the indications for and use of different anticoagulation, antiplatelet, and thrombolytic agents. In addition, we describe some of most common thrombotic complications and their management in the pediatric CHD population.

Risk factors for venous thromboembolic events in pediatric surgical patients: Defining indications for prophylaxis

BACKGROUND

Venous thromboembolism (VTE) in pediatric surgical patients is a rare event. The risk factors for VTE in pediatric general surgery patients undergoing abdominopelvic procedures are unknown.

STUDY DESIGN

The American College of Surgeon's National Surgical Quality Improvement Program-Pediatric (NSQIP-P) database (2012-2015) was queried for patients with VTE after abdominopelvic general surgery procedures. Patient and operative variables were assessed to identify risk factors associated with VTE and develop a pediatric risk score.

RESULTS

From 2012-2015, 68 of 34,813 (0.20%) patients who underwent abdominopelvic general surgery procedures were diagnosed with VTE. On multivariate analysis, there was no increased risk of VTE based on concomitant malignancy, chemotherapy, inflammatory bowel disease, or laparoscopic surgical approach, while a higher rate of VTE was identified among female patients. The odds of experiencing VTE were increased on stepwise regression for patients older than 15 years and those with preexisting renal failure or a diagnosis of septic shock, patients with American Society of Anesthesia (ASA) classification ≥ 2, and for anesthesia time longer than 2 h. The combination of age > 15 years, ASA classification ≥ 2, anesthesia time > 2 h, renal failure, and septic shock was included in a model for predicting risk of VTE (AUC = 0.907, sensitivity 84.4%, specificity 88.2%).

CONCLUSION

VTE is rare in pediatric patients, but prediction modeling may help identify those patients at heightened risk. Additional studies are needed to validate the factors identified in this study in a risk assessment model as well as to assess the efficacy and cost-effectiveness of prophylaxis methods.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Thrombolysis With Recombinant Tissue Plasminogen Activator in 7 Children

The information about the thromboembolic events, the optimal treatment choice, the dose, and duration of antithrombotic therapy in children are limited. More clinical data are required. Recombinant tissue plasminogen activator (r-tPA) is increasingly used in pediatric thrombosis. We retrospectively analyzed the clinical course of 7 children (9.3 ± 2.1 years; 34 days to 16 years) with arterial thrombosis (n = 1) and intracardiac thrombosis (n = 6). The children were treated with r-tPA. The dose ranged between 0.2 and 0.4 mg/kg per h infused for 3 to 4 hours. This dose was repeated between 2 to 7 times till the thrombolysis was achieved. Treatment side effects were closely monitored. Complete clot lysis was achieved in all cases. None of them had severe bleeding except mild recurrent epistaxis occurring in 2 cases. In conclusion, r-tPA is an effective and safe therapy under close hemostatic control in children.

Thrombophilia testing in neonates and infants with thrombosis

In neonates and infants with idiopathic venous thrombosis (VTE) and in pediatric populations in which thromboses were associated with medical diseases, inherited thrombophilia (IT) have been described as risk factors. Follow-up data for VTE recurrence in neonates suggest a recurrence rate between 3% in provoked and 21% in idiopathic VTE. Apart from underlying medical conditions, recently reported systematic reviews on pediatric VTE have shown significant associations between factor V G1691A, factor II G20210A, and deficiencies of protein C, protein S and antithrombin, even more pronounced when combined IT were involved. Independent from the age at first VTE onset, the pooled odds ratios (OR: single IT) for VTE ranged from 2.4 for the factor II G20210A mutation to 9.4 in neonates and infants with antithrombin deficiency. The pooled OR for persistent antiphospholipid antibodies/lupus anticoagulants was 4.9 for pediatric patients with venous VTE. The factor II G20210A mutation (OR: 2.1), and deficiencies of protein C (OR: 2.4), S (OR: 3.1) and antithrombin (OR: 3.0) also played a significant role at recurrence. Based on these data, screening and treatment algorithms must be discussed.

Incidence of and risk factors for childhood thrombosis: a single-center experience in Ankara, Turkey

This study was conducted to analyze the incidence of and risk for thrombosis in thrombotic children monitored in the Department of Pediatric Hematology of our hospital at the time of diagnosis, in addition to the clinical characteristics of those patients. The clinical and laboratory findings of 122 patients diagnosed with thrombosis from 1997 to 2006 were retrospectively analyzed. The incidence of thrombosis was 88.6/10,000 hospital admissions. The authors found that 31.1% of the patients studied had a thrombosis in more than 1 region. The incidence of thrombosis by anatomic site was as follows: 42 thromboses in the peripheral arterial system, 39 in an intracardiac region, 38 in the abdominal venous system, 36 in the deep peripheral venous system, and 28 in the cerebral vascular system. The mean age of the patients at the time of diagnosis was 4.9 years. Of the patients studied, 10.7% were neonates, 35.3% were infants younger than 1 year, and 48.4% were younger than 2 years. Most of the patients had a congenital cardiac disease and spontaneous thrombosis, and 66.1% had at least 1 acquired risk factor, the most common of which were having undergone surgery (42%) or wearing a central venous catheter (39%). A hereditary factor for the development of thrombosis was present in 54% of the patients. The most frequently observed hereditary risk factor was the MTHFR 677C-T mutation, and the second most common was the factor V Leiden mutation. Thrombosis should be considered a systemic disorder, and thrombotic patients should be evaluated with appropriate methods. Acquired and hereditary risk factors should be analyzed systematically in thrombotic patients.

Impact of Inherited Thrombophilia on Venous Thromboembolism in Children

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.

Venous thromboembolism in children

With improved pediatric survival from serious underlying illnesses, greater use of invasive vascular procedures and devices, and a growing awareness that vascular events occur among the young, venous thromboembolism (VTE) increasingly is recognized as a critical pediatric concern. This review provides background on etiology and epidemiology in this disorder, followed by an in-depth discussion of approaches to the clinical characterization, diagnostic evaluation, and management of pediatric VTE. Prognostic indicators and long-term outcomes are considered, with emphasis on available evidence underlying current knowledge and key questions for further investigation.

Venous thromboembolism in Thai children

This is a retrospective study of 24 pediatric venous thromboembolism (VTE) patients with or without pulmonary embolism, conducted in Bangkok, Thailand, between 1981 and 2005. The incidence rate of VTE in Thai children was 3.9/10,000 hospital admissions per year. The median age was 11.7 years. Seventy-five percent of the patients had at least one associated medical condition accounting for the VTE; the two most common conditions, however, were infection and malignancy. Pulmonary embolism occurred in 29% of patients. Observed outcomes of VTE in this series included death (13%), postphlebitic syndrome (13%), and recurrence (26%). Genetic risk factors were explored in 19 patients, and no factor V Leiden or prothrombin 20210 mutations were detected. Protein C deficiency was found in 4 patients.

The influence of risk factors in promoting thrombosis during childhood: the role of acquired factors

Thrombo-embolism in childhood is a multifactorial disorder. The present study is a case-control study that investigated the role of genetic and acquired risk factors in 60 children with thrombosis and compared the results with the controls. Acquired and inherited risk factors precipitating thrombosis were present in 75 and 40% of the thrombotic children, respectively. The most frequent acquired risk factor was infection (58%). Of the genetic factors, factor V G20210A was the most common (38%). The comparison of the genetic and acquired risk factors in thrombotic versus nonthrombotic settings identified that acquired factors played a more significant role in causing thrombosis (OR:14.44; 95% CI: 7.05-29.94, p < .001). This study has clearly suggested that the prevention of acquired risk factors, particularly infection, could decrease the risk of thrombosis in pediatric cases.

Long-term outcomes of venous thrombosis in children

PURPOSE OF REVIEW

Venous thromboembolism has become an increasingly recognized clinical entity in children over the past decade. Recently, important efforts have been made to track post thrombotic outcomes. The present review discusses the knowledge gained from seminal studies in the field over the past decade, with particular emphasis on the findings of numerous published reports on outcomes of various types of venous thromboembolism in the pediatric literature from January 2003 to January 2005.

RECENT FINDINGS

Large cohort studies involving acute venous thromboembolism of all types in children have recently confirmed a rather low frequency of recurrent venous thromboembolism, but have shown a lack of thrombus resolution following standard-duration anticoagulant therapy in as many as 50% of patients. In addition, the development of the post thrombotic syndrome has been demonstrated in greater than one third of children with venous thromboembolism involving the extremities. Persistent thrombosis despite adequate anticoagulation has been independently associated with complete vaso-occlusion at diagnosis. Furthermore, the presence of elevated levels of factor VIII and D-dimer either at diagnosis or following three to six months anticoagulation has now been defined as a predictor of adverse long-term outcomes of pediatric thrombosis.

SUMMARY

This body of work indicates that the various forms of venous thromboembolism in children are in general associated with a considerable degree of adverse outcomes, particularly in the form of venous thromboembolism-related mortality, recurrent thromboembolism, and development of post thrombotic syndrome. Advances in the prediction of post thrombotic outcomes have begun, and must continue to facilitate a risk-stratified approach to antithrombotic management in children, and to ultimately achieve meaningful improvements in long-term outcomes.