Long-term outcomes of venous thrombosis in children

Use of a real-time risk-prediction model to identify pediatric patients at risk for thromboembolic events: study protocol for the Children's Likelihood Of Thrombosis (CLOT) trial

BACKGROUND

Pediatric patients have increasing rates of hospital-associated venous thromboembolism (HA-VTE), and while several risk-prediction models have been developed, few are designed to assess all general pediatric patients, and none has been shown to improve patient outcomes when implemented in routine clinical care.

METHODS

The Children's Likelihood Of Thrombosis (CLOT) trial is an ongoing pragmatic randomized trial being conducted starting November 2, 2020, in the inpatient units at Monroe Carell Jr. Children's Hospital at Vanderbilt in Nashville, TN, USA. All admitted patients who are 21 years of age and younger are automatically enrolled in the trial and randomly assigned to receive either the current standard-of-care anticoagulation practice or the study intervention. Patients randomized to the intervention arm are assigned an HA-VTE risk probability that is calculated from a validated VTE risk-prediction model; the model is updated daily with the most recent clinical information. Patients in the intervention arm with elevated risk (predicted probability of HA-VTE ≥ 0.025) have an additional review of their clinical course by a team of dedicated hematologists, who make recommendations including pharmacologic prophylaxis with anticoagulation, if appropriate. The anticipated enrollment is approximately 15,000 patients. The primary outcome is the occurrence of HA-VTE. Secondary outcomes include initiation of anticoagulation, reasons for not initiating anticoagulation among patients for whom it was recommended, and adverse bleeding events. Subgroup analyses will be conducted among patients with elevated HA-VTE risk.

DISCUSSION

This ongoing pragmatic randomized trial will provide a prospective assessment of a pediatric risk-prediction tool used to identify hospitalized patients at elevated risk of developing HA-VTE.  TRIAL REGISTRATION: ClinicalTrials.gov NCT04574895. Registered on September 28, 2020. Date of first patient enrollment: November 2, 2020.

A Real-time Risk-Prediction Model for Pediatric Venous Thromboembolic Events

BACKGROUND

Hospital-associated venous thromboembolism (HA-VTE) is an increasing cause of morbidity in pediatric populations, yet identification of high-risk patients remains challenging. General pediatric models have been derived from case-control studies, but few have been validated. We developed and validated a predictive model for pediatric HA-VTE using a large, retrospective cohort.

METHODS

The derivation cohort included 111 352 admissions to Monroe Carell Jr. Children's Hospital at Vanderbilt. Potential variables were identified a priori, and corresponding data were extracted. Logistic regression was used to estimate the association of potential risk factors with development of HA-VTE. Variable inclusion in the model was based on univariate analysis, availability in routine medical records, and clinician expertise. The model was validated by using a separate cohort with 44 138 admissions.

RESULTS

A total of 815 encounters were identified with HA-VTE in the derivation cohort. Variables strongly associated with HA-VTE include history of thrombosis (odds ratio [OR] 8.7; 95% confidence interval [CI] 6.6-11.3; P < .01), presence of a central line (OR 4.9; 95% CI 4.0-5.8; P < .01), and patients with cardiology conditions (OR 4.0; 95% CI 3.3-4.8; P < .01). Eleven variables were included, which yielded excellent discriminatory ability in both the derivation cohort (concordance statistic = 0.908) and the validation cohort (concordance statistic = 0.904).

CONCLUSIONS

We created and validated a risk-prediction model that identifies pediatric patients at risk for HA-VTE development. We anticipate early identification of high-risk patients will increase prophylactic interventions and decrease the incidence of pediatric HA-VTE.

Physical activity in children at risk of postthrombotic sequelae: a pilot randomized controlled trial

Increased physical activity is protective against worsening of postthrombotic syndrome (PTS) in adults. We assessed patient eligibility, consent, adherence, and retention rates in a pilot trial of prescribed physical activity following venous thromboembolism (VTE) in children. Secondary objectives were to describe the within-subject changes in PTS, quality of life, and coagulation biomarkers before and after the intervention in each group. We enrolled and randomized patients between 7 and 21 years of age to the physical activity group or the standard care (education-only) group in a 1:1 allocation ratio. The physical activity group wore a Fitbit for 4 weeks to determine habitual activity and then increased activity over an 8-week "active" period, followed by a 4-week "do-as-you-wish" period. Two hundred thirty-five children were diagnosed with VTE; 111 patients were screened, of whom 40 (36%) met study eligibility criteria. Of these, 23 (57%) consented to participate and were randomized (Fitbit,11; standard group, 12). The trial was of greater interest to overweight and obese children, as they comprised 83% of consented patients. Only 33% adhered to the activity prescription, and 65% (15/23) completed the trial. The PTS scores (P = .001) improved in the physical activity group compared with the education-only group. It is feasible to enroll and randomize pediatric VTE patients to a prescribed physical activity regimen 3 months following VTE. Metrics for adherence to enhanced physical activity and retention were not met. These results provide the rationale to explore low adherence and retention rates before moving forward with a larger trial of exercise training following VTE. This trial was registered at www.clinicaltrials.gov as #NCT03075761.

Community-Onset Venous Thromboembolism in Children: Pediatric Emergency Medicine Perspectives

Pediatric venous thromboembolism (VTE) is a condition increasingly encountered by emergency medicine physicians. Unfortunately, despite increased incidence, the diagnosis of pediatric VTE relies on a high index of suspicion from clinicians. Delays in diagnosis and initiation of treatment can lead to poor outcomes in children, including an increased risk of mortality from pulmonary embolism, increased risk of VTE recurrence, and the development of the post-thrombotic syndrome. The majority of pediatric VTE events are associated with the presence of at least one underlying prothrombotic risk. Timely recognition of these risk factors in the emergency department (ED) setting is paramount for a prompt diagnosis and treatment initiation. Compared with children with hospital-acquired VTE, children presenting to the ED with new onset VTE tend to be older (>11 years of age), have a lower incidence of co-morbidities, and present more frequently with a deep venous thrombosis of the lower extremity. Currently, there are no validated pediatric-specific VTE clinical pretest probability tools that reliably assist with the accurate and timely diagnosis of pediatric VTE. Compression ultrasound with Doppler is the most common imaging modality used for VTE diagnosis, and low molecular weight heparins are the most common anticoagulants initiated in children presenting with VTE in the ED. Special consideration should be given to patients who present to the ED already on anticoagulation therapy who may require acute management for clinically-significant bleeding or change in antithrombotic therapy approach for progression/recurrence of VTE.

Reduced Physical Activity Levels in Children after a First Episode of Acute Venous Thromboembolism

OBJECTIVE

To assess physical activity in children following acute venous thromboembolism (VTE), examine predictors of reduced physical activity and its relationship to post-thrombotic syndrome.

STUDY DESIGN

Using a case-control study design, we enrolled 44 children with acute VTE, and compared physical activity using the Godin-Shephard Leisure-Time Physical Activity Questionnaire and health-related quality of life at 3 and 6 months after diagnosis relative to 44 age- and sex-matched controls. We assessed post-thrombotic syndrome scores using the Manco-Johnson Instrument to measure symptoms and signs attributed to sequelae of DVT in cases.

RESULTS

The physical activity of VTE cases was decreased at 3 months after diagnosis (36.6 ± 29.0 vs 56.8 ± 25.0; P = .002), but the differences disappeared at 6 months (57.5 ± 39.0 vs 56.8 ± 25.0; P = .60) relative to controls. At 3 and 6 months after diagnosis, overall, 70% and 50% of VTE cases were below their pre-VTE physical activity levels; providers did not address physical activity in the majority. In multivariable analysis, physical activity of cases was lower by 32 points for completely veno-occlusive thrombosis at diagnosis, 11 points for a diagnosis of pulmonary embolism relative to DVT, and increased by 0.72 points for every unit increase in health-related quality of life score. Physical activity at 3 months after diagnosis did not predict the short-term risk of post-thrombotic syndrome.

CONCLUSIONS

VTE limits physical activity in children in the first 3 months after the acute event, but the differences were nonexistent at 6 months. Only 50 percent of VTE survivors resume their pre-VTE physical activity levels within 6 months after diagnosis.

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.

Design and rationale for the DIVERSITY study: An open-label, randomized study of dabigatran etexilate for pediatric venous thromboembolism

BACKGROUND

The current standard of care (SOC) for pediatric venous thromboembolism (VTE) comprises unfractionated heparin (UFH), or low-molecular-weight heparin (LMWH) followed by LMWH or vitamin K antagonists, all of which have limitations. Dabigatran etexilate (DE) has demonstrated efficacy and safety for adult VTE and has the potential to overcome some of the limitations of the current SOC. Pediatric trials are needed to establish dosing in children and to confirm that results obtained in adults are applicable in the pediatric setting.

OBJECTIVES

To describe the design and rationale of a planned phase IIb/III trial that will evaluate a proposed dosing algorithm for DE and assess the safety and efficacy of DE versus SOC for pediatric VTE treatment.

PATIENTS/METHODS

An open-label, randomized, parallel-group noninferiority study will be conducted in approximately 180 patients aged 0 to <18 years with VTE, who have received initial UFH or LMWH treatment and who are expected to require ≥3 months of anticoagulation therapy. Patients will receive DE or SOC for 3 months. DE will be administered twice daily as capsules, pellets, or an oral liquid formulation according to patient age. Initial doses will be calculated using a proposed dosing algorithm.

RESULTS

There will be two coprimary endpoints: a composite efficacy endpoint comprising the proportion of patients with complete thrombus resolution, freedom from recurrent VTE and VTE-related mortality, and a safety endpoint: freedom from major bleeding events.

CONCLUSION

Findings will provide valuable information regarding the efficacy and safety of DE for the treatment of pediatric VTE. ClinicalTrials.gov registration number: NCT01895777.

Pediatric issues in thrombosis and hemostasis: The how and why of venous thromboembolism risk stratification in hospitalized children

Multiple observational studies have identified risk factors for venous thromboembolism (VTE) in hospitalized children, but very few interventional studies have assessed the safety and efficacy of thromboprophylaxis in this population. In recent years, however, evidence in pediatric VTE risk stratification has grown considerably. This has led to the conception of a pediatric subpopulation-specific risk-based paradigm for mechanical and pharmacological thromboprophylaxis in hospitalized children. More research is required to validate and further refine pediatric subpopulation-specific risk models and to subsequently investigate risk-stratified thromboprophylaxis strategies for hospitalized children.

Safety, tolerability and clinical pharmacology of dabigatran etexilate in adolescents

Venous thromboembolism (VTE) incidence is increasing among children owing to many factors, including improved diagnosis of VTE. There is a need for alternative treatment options. Our objective was to investigate the safety, pharmacokinetics (PK) and pharmacodynamics (PD) of dabigatran etexilate in adolescents with VTE. Adolescents aged 12 to <18 years (n = 9) who successfully completed planned treatment for primary VTE were administered dabigatran etexilate twice daily for three days; initially 1.71 (± 10%) mg/kg (80% of a 150 mg/70 kg twice daily adult dose), followed by 2.14 (± 10%) mg/kg (target adult dose adjusted for patient’s weight), if there were no safety concerns. No bleeding events, deaths or drug-related serious adverse events (AEs) were reported; three treatment-emergent AEs, all gastrointestinal-related, occurred in two patients. In these adolescent patients with normal renal function, presumed steady-state trough plasma concentrations of dabigatran were low (geometric mean dosenormalised total dabigatran plasma concentration: 0.493 ng/ml/mg at 72 hours). Total dabigatran concentrations were well predicted by the RE-LY® population PK model (94% of trough concentrations were within the 80% prediction interval). The relationship between total dabigatran plasma concentration, diluted thrombin time and ecarin clotting time (ECT) was linear; the relationship with activated partial thromboplastin time (aPTT) was non-linear. Adult population PK/PD models predicted the adolescent concentration–ECT and –aPTT relationships well. In conclusion, dabigatran etexilate was generally well tolerated, except for occurrence of dyspepsia in two patients, over the three-day treatment period. The dabigatran PK/PD relationship observed in adolescent patients was similar to that in adult patients.

Institution where work was performed: Main clinical study site: Children’s Hospital of Eastern Ontario, Ottawa, Ontario, Canada.

This study is registered at ClinicalTrials.gov (NCT00844415).

Markers of coagulation activation, inflammation and fibrinolysis as predictors of poor outcomes after pediatric venous thromboembolism: A systematic review and meta-analysis

BACKGROUND

Sequelae of venous thromboembolism (VTE) in children include recurrence, development of post thrombotic syndrome (PTS) when venous return from a limb is affected and chronic thromboembolic pulmonary hypertension (CTEPH) after pulmonary embolism. Identification of laboratory-based risk factors may be useful for individualized risk assessment for VTE sequelae. Coagulation activation and inflammation may contribute to their pathophysiology. We performed a systematic review to investigate the association between biomarkers of coagulation activation, inflammation and fibrinolysis and adverse VTE outcomes in children and young adults.

METHODS

A systematic search of electronic databases, PubMed (NIH), EMBASE (Ovid), Web of Science (Thompson Reuters), and SCOPUS (Elsevier) for studies published through November 2016 was conducted using "VTE" including MeSH terms for "coagulation activation," "inflammation" and "fibrinolysis," with no limit on publication date. A study was eligible for inclusion when it evaluated patients (< 21years) with VTE and biomarkers of coagulation activation, inflammation, and fibrinolysis and assessed for their association with development of adverse thrombotic outcomes. A modified Newcastle Ottawa Scale was applied to examine the quality of included studies.

RESULTS

Our search strategy yielded 200 references. A total of 3 cohort studies representing 220 patients with VTE were included. Two authors independently assessed all references for inclusion. Three studies (2 prospective cohort and one mixed cohort study) were identified that reported on biomarkers of coagulation activation, inflammation and fibrinolysis, checked at least once after VTE diagnosis and assessed association with primary outcomes of recurrent VTE, PTS and CTEPH. Studies varied with regards to definition of outcomes, the type of biomarkers measured and time point of measurement. We were unable to meta-analyze results due to marked clinical heterogeneity and <3 studies available for each biomarker. Descriptively, a significant association was found for elevated plasma levels of FVIII and D-dimer for a compound outcome of PTS, recurrence and progression in one study, and positive lupus anticoagulant at DVT diagnosis and subsequent PTS by another study. No studies were found for CTEPH.

CONCLUSIONS

Elevated D-dimer, FVIII and lupus anticoagulant show promise for predicting recurrent VTE and PTS in children and young adults. Further research is needed to elucidate whether these markers might be useful to predict development of adverse outcomes after VTE in children.

Paediatric venous thromboembolism: a report from the Italian Registry of Thrombosis in Children (RITI)

BACKGROUND

The Italian Registry of Thrombosis in Children (RITI) was established by a multidisciplinary team with the aims of improving knowledge about neonatal and paediatric thrombotic events in Italy and providing a preliminary source of data for the future development of specific clinical trials and diagnostic-therapeutic protocols.

MATERIALS AND METHODS

We analysed the subset of RITI data concerning paediatric systemic venous thromboembolic events that occurred between January 2007 and June 2013.

RESULTS

Eighty-five deep venous thromboses and seven pulmonary emboli were registered in the RITI. A prevalence peak was observed in children aged 10 to 18 years and, unexpectedly, in children aged 1 to 5 years. A central venous line was the main risk factor (55% of venous thromboembolic events); surgery (not cardiac) (25%), concomitant infections (23%) and malignancy (22%) were the clinical conditions most often associated with the onset of venous thromboembolism. There was a diagnostic delay of more than 24 hours in 37% of the venous thromboembolic events. Doppler ultrasound was the most widely used test for the objective diagnosis of deep venous thrombosis (87%). Antithrombotic therapy was administered in 96% of venous thromboembolic events, mainly low molecular weight heparin (60%). In 2% of cases recurrences occurred, while post-thrombotic syndrome developed in 8.5% of cases.

DISCUSSION

Although the data from the RITI are largely in agreement with published data, peaks of prevalence of thrombosis, risk factors and objective tests used for the diagnosis showed some peculiarities which may deserve attention.

Endovascular thrombolysis to salvage central venous access in children with catheter-associated upper extremity deep vein thrombosis: technique and initial results

Nine patients (average age 8.3 years, range 20 days to 17 years; average weight 31 kg, range 2.7-79 kg) with catheter-associated UE-DVT underwent upper extremity venous thrombolysis with the goal of access salvage. Catheter directed therapy with alteplase (tPA), balloon angioplasty, and mechanical thrombectomy was used in all cases. The mean total dose of TPA was 15 mg (range 1-40 mg). Venous access was ultimately preserved in all patients. No stents or superior vena cava filters were used. There was one episode of symptomatic clinically suspected pulmonary embolism managed by systemic tPA and heparin without long term sequaele. Mean imaging and clinical follow-up was 351 ± 208 and 613 ± 498 days respectively. Endovenous thrombolysis for catheter-associated upper-extremity DVT in children may be safe and effective and could be considered particularly in patients in whom long-term venous access is needed.

Management and Outcomes of Patients with Occlusive Thrombosis after Pediatric Cardiac Surgery

OBJECTIVES

To evaluate management and outcomes of thrombosis after pediatric cardiac surgery and stratify thrombi according to risk of short- and long-term complications to better guide therapeutic choices.

STUDY DESIGN

Retrospective review was performed of 513 thrombi (400 occlusive) diagnosed after 213 pediatric cardiac operations. Long-term outcomes over time were assessed with the use of parametric hazard regression models.

RESULTS

Serious complications and/or high-intensity treatment occurred with 17%-24% of thrombi depending on location, most commonly in thrombi affecting the cardiac and cerebral circulation. Bleeding complications affected 13% of patients; associated factors included thrombolytics (OR 8.7, P < .001), greater daily dose of unfractionated heparin (OR 1.25 per 5 U/kg/day, P = .03), and extracorporeal support (OR 4.5, P = .007). Radiologic thrombus persistence was identified in 30% ± 3% at 12 months; associated factors included extracorporeal support (hazard ratio [HR] 1.9, P = .003), venous (HR 1.7, P = .003), and occlusive thrombi at presentation (HR 1.8, P = .001); greater oxygen saturation before surgery (HR 1.13/10%, P = .05) and thrombi in femoral veins (HR 1.9, P = .001) were associated with increased hazard of resolution. Freedom from postthrombotic syndrome was 83% ± 4% at 6 years, greater number of persistent vessel segment occlusions (HR 1.8/vessel, P = .001) and greater fibrinogen at diagnosis (HR 1.1 per g/L, P = .02) were associated with increased hazard.

CONCLUSIONS

Thrombosis outcomes after pediatric cardiac surgery remain suboptimal. Given that more intensive treatment would likely increase the risk of bleeding, the focus should be on both thrombosis-prevention strategies, as well as in tailoring therapy according to a thrombosis outcome risk stratification approach.

Acute paraplegia in a preterm infant with cerebral sinovenous thrombosis

We report the case of a 1-month old, 28-week gestational age infant who presented with acute paraplegia after cardiopulmonary arrest. Later imaging confirms cerebral sinovenous thrombosis (CSVT) and a suspected infarction in the conus medullaris of the spinal cord. A prothrombotic state may explain the numerous areas of infarction visualized on neuroimaging. To our knowledge this is the first case report of acute and persistent paraplegia in an infant with CSVT and conus medullaris injury, which may be due to venous infarction of the spinal cord.

Challenging aspects of managing hemostasis in adolescents

The prevalence of symptomatic childhood venous thromboembolism increases among adolescents. The occurrence of nonhereditary prothrombotic risk factors, e.g. oral contraceptive pills, often prescribed to adolescent females for various indications, such as tobacco use, obesity and hypertension may trigger symptomatic thrombosis, especially in carriers of genetic thrombophilia traits. On the other hand, heavy menstrual bleeding is a common clinical problem of young adolescent women. A proper diagnostic workup of these women may enable physicians to detect and treat congenital bleeding disorders, e.g. von Willebrand disease, presenting with menorrhagia. The challenges of diagnosis and treatment of either thrombosis or bleeding disorders in young adults will be discussed in this review.

Endovascular venous thrombolysis in children younger than 24 months

PURPOSE

To evaluate the technical feasibility and safety of percutaneous endovascular thrombolysis for extremity deep venous thrombosis (DVT) in children < 24 months old.

MATERIALS AND METHODS

A retrospective chart review of a clinical and imaging database was performed for pediatric patients who underwent endovascular therapy for DVT between January 2010 and July 2013. Indications, techniques, technical and clinical success, and complications were reviewed. Techniques for thrombolysis included catheter-directed therapy (CDT) using alteplase infusion via a multi-side hole catheter, mechanical thrombectomy, and angioplasty. Short-term outcomes were assessed using surgical and imaging follow-up examinations for patency of the targeted vessel. Patients included 11 children (mean age, 9 mo; range, 3 wk-23 mo) who consecutively underwent endovascular thrombolysis for upper extremity (n = 6) or lower extremity (n = 5) DVT. The most common indication was preservation of venous access for future cardiac surgery or medical therapy.

RESULTS

The most common risk factor was the presence of a central venous catheter (10 of 11 patients). All patients with upper extremity DVT had congenital heart disease. CDT and angioplasty were performed in all patients. Venous patency was established in all patients. A grade III (95%-100%) thrombolysis response was achieved in seven patients, and a grade II (50%-95%) thrombolysis response was achieved in four patients. A major complication of pulmonary embolism occurred in one patient with upper extremity thrombolysis and was managed by intravenous systemic alteplase and heparin. No recurrence of thrombosis was found on average follow-up of 11.8 months (range, 1-41 mo).

CONCLUSIONS

Percutaneous endovascular thrombolysis for extremity DVT is safe and technically feasible in children < 24 months old.

Antithrombotic therapies: anticoagulation and thrombolysis

Pediatric deep vein thrombosis is an increasingly recognized phenomenon, especially with advances in treatment and supportive care of critically ill children and with better diagnostic capabilities. High-quality evidence and uniform management guidelines for antithrombotic treatment, particularly thrombolytic therapy, remain limited. Optimal dosing, intensity and duration strategies for anticoagulation as well as thrombolytic regimens that maximize efficacy and safety need to be determined through well-designed clinical trials using use of a risk-stratified approach.

Management of thrombotic complications in acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common type of cancer diagnosed in children, and has been reported as the most common malignancy associated with thromboembolism in the pediatric age group. Treatment with Escherichia coli asparaginase, concomitant steroids, presence of central venous lines, and thrombophilic abnormalities are established risk factors for thromboembolism. The incidence varies with age, co-morbidities and chemotherapy regimens but the risk is highest during the induction and intensification phases. Treatment is necessary in majority of children to prevent serious sequelae. Mortality from thromboembolic events in any location is 2 to 4 % and the risk of recurrence is 7 to 10 %, further enhanced in the setting of malignancy. Randomized trials of venous thromboembolism (VTE) management in pediatric patients with ALL are lacking due to the low overall incidence, resulting in considerable variation in practice. The objective of this article is to review current knowledge on the treatment and prevention of thrombosis associated with pediatric ALL.

Characteristics of abdominal vein thrombosis in children and adults

The demographic and clinical characteristics of adults and children with lower extremity deep-vein thrombosis and/or pulmonary embolism (LE DVT/PE) may differ from those with abdominal vein thrombosis (abdominal VT). Abdominal VT can be a presenting sign of an underlying prothrombotic state, and its presence in the setting of known disease might have prognostic implications different from LE DVT/PE. This study describes clinical presentations of abdominal VT compared to LE DVT/PE in adults and children. We analysed prospectively-collected data from consecutive consenting patients enrolled in one of seven Centers for Disease Control and Prevention (CDC) funded Thrombosis and Hemostasis Network Centers from August 2003 to April 2011 to compare the demographic and clinical characteristics of adults and children with abdominal VT. Both adults and children with abdominal VT tended to be younger and have a lower body mass index (BMI) than those with LE DVT/PE. Of patients with abdominal VT, children were more likely to have inferior vena cava (IVC) thrombosis than adults. For adults with venous thromboembolism (VTE), relatively more women had abdominal VT than LE DVT/PE, while the proportions with LE DVT/PE and abdominal VT by sex were similar in children. Children with abdominal VT were more likely to have diagnosed inherited thrombophilia, while trauma was more common in children with LE DVT/PE. In conclusion, both children and adults with abdominal VT were younger with a lower BMI than those with LE DVT/PE. Significant differences exist between children and adults in respect to abdominal VT compared to LE DVT/PE.

Venous thrombosis in children: an emerging issue

More and more cases of venous thrombosis are diagnosed in children thanks to newer imaging modalities. Central venous catheters have become commonplace in the care of critically ill children and have contributed to the increased rate of thrombotic events. Lastly, children who develop life-threatening or chronic medical conditions are surviving longer because of advanced medical therapies; these intensive therapies can be complicated by events such as thrombosis. Over the last 10 years, specific guidelines for treating thrombosis in children have become available. Nevertheless, in many situations anticoagulant treatment is specially tailored to each individual patient's needs. Some new antithrombotic drugs which have undergone clinical testing in adults might be beneficial to paediatric patients with thromboembolic disorders; unfortunately, clinical data and reports on the use of these drugs in children, when available, are extremely limited. The aim of this review is to provide physicians with enough background information to be able to manage thrombosis in children. First, by helping them detect a thrombotic event in a child. Upon confirmation of the diagnosis, the physician will request the appropriate tests and will choose the best treatment on the basis of the guidelines and recommendations. Moreover, the paediatrician will have the information he or she needs to identify which children are at highest risk of acute thrombotic events and relevant long-term sequelae and, therefore, to decide on the appropriate prophylactic or pharmacologic strategy. Lastly, we would like to provide the paediatrician with information on future drugs with regard to the treatment and prophylaxis of thrombosis.

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.

The Post-Thrombotic Syndrome

The post-thrombotic syndrome (PTS) is an important chronic complication of deep vein thrombosis (DVT). The present review focuses on risk determinants of PTS after DVT and available means to prevent and treat PTS. More than one-third of patients with DVT will develop PTS, and 5% to 10% of patients develop severe PTS, which can manifest as venous ulcers. PTS has an adverse impact on quality of life as well as significant socioeconomic consequences. The main risk factors for PTS are persistent leg symptoms 1 month after acute DVT, anatomically extensive DVT, recurrent ipsilateral DVT, obesity, and older age. Subtherapeutic dosing of initial oral anticoagulation therapy for DVT treatment may also be linked to subsequent PTS. By preventing the initial DVT and DVT recurrence, primary and secondary prophylaxis of DVT will prevent cases of PTS. Daily use of elastic compression stockings for 2 years after proximal DVT appears to reduce the risk of PTS; however, uncertainty remains regarding optimal duration of use, optimal compression strength, and usefulness after distal DVT. The cornerstone of managing PTS is compression therapy, primarily using elastic compression stockings. Venoactive medications such as aescin and rutosides may provide short-term relief of PTS symptoms. Further studies to elucidate the pathophysiology of PTS, to identify clinical and biological risk factors, and to test new preventive and therapeutic approaches to PTS are needed.

Validation of upper extremity post-thrombotic syndrome outcome measurement in children

Using the Manco-Johnson instrument in a derivation cohort of 107 children with or without a central venous catheter, upper extremity physical findings of post-thrombotic syndrome were absent, and the pain score was 0 in all but one child. Interrater reliability in an independent validation cohort (n = 38) of children with or without upper extremity deep venous thrombosis was 97%-100%.

Post-thrombotic syndrome in children: a systematic review of frequency of occurrence, validity of outcome measures, and prognostic factors

BACKGROUND

Post-thrombotic syndrome is a manifestation of chronic venous insufficiency following deep venous thrombosis. This systematic review was conducted to critically evaluate pediatric evidence on frequency of occurrence, validity of outcome measures, and prognostic indicators of post-thrombotic syndrome.

DESIGN AND METHODS

A comprehensive literature search of original reports revealed 19 eligible studies, totaling 977 patients with upper/lower extremity deep venous thrombosis. Calculated weighted mean frequency of post-thrombotic syndrome was 26% (95% confidence interval: 23-28%) overall, and differed significantly by prospective/non-prospective analysis and use/non-use of a standardized outcome measure.

RESULTS

Standardized post-thrombotic syndrome outcome measures included an adaptation of the Villalta scale, the Clinical-Etiologic-Anatomic-Pathologic classification, and the Manco-Johnson instrument. Data on validity were reported only for the Manco-Johnson instrument. No publications on post-thrombotic syndrome-related quality of life outcomes were identified. Candidate prognostic factors for post-thrombotic syndrome in prospective studies included use/non-use of thrombolysis and plasma levels of factor VIII activity and D-dimer.

CONCLUSIONS

Given that affected children must endure chronic sequelae for many decades, it is imperative that future collaborative pediatric prospective cohort studies and trials assess as key objectives and outcomes the incidence, severity, prognostic indicators, and health impact of post-thrombotic syndrome, using validated measures.

How I treat postthrombotic syndrome

Postthrombotic syndrome (PTS) is a chronic complication of deep venous thrombosis (DVT) that reduces quality of life and has important socioeconomic consequences. More than one-third of patients with DVT will develop PTS, and 5% to 10% of patients will develop severe PTS, which may manifest as venous ulceration. The principal risk factors for PTS are persistent leg symptoms 1 month after the acute episode of DVT, extensive DVT, recurrent ipsilateral DVT, obesity, and older age. Daily use of elastic compression stockings (ECSs) for 2 years after proximal DVT appears to reduce the risk of PTS; however, there is uncertainty about optimal duration of use and compression strength of ECSs and the magnitude of their effect. The cornerstone of managing PTS is compression therapy, primarily using ECSs. Venoactive medications such as aescin and rutoside may provide short-term relief of PTS symptoms. The likelihood of developing PTS after DVT should be discussed with patients, and symptoms and signs of PTS should be monitored during clinical follow-up. Further studies to elucidate the pathophysiology of PTS, to identify clinical and biologic risk factors, and to test new preventive and therapeutic approaches to PTS are needed to ultimately improve the long-term prognosis of patients with DVT.

Thrombosis in childhood acute lymphoblastic leukaemia: epidemiology, aetiology, diagnosis, prevention and treatment

Acute lymphoblastic leukaemia (ALL) is the most common malignancy associated with venous thromboembolism (VTE) in children. The prevalence of symptomatic VTE ranges from 0% to 36%, and the variation can be explained, at least in part, by differences in chemotherapeutic protocols. The mechanism for increased risk of VTE is associated with alterations in the haemostatic system by use of L-asparaginase (ASP) alone or in combination with vincristine or prednisone, presence of central venous lines (CVLs) and/or inherited thrombophilia. The children at greatest risk are generally those receiving Escherichia coli ASP concomitant with prednisone. The majority of symptomatic VTEs occur in the central nervous system or in the upper venous system. In the majority of cases, asymptomatic VTEs are associated with CVLs. External CVLs are affected more often than internal CVLs. Evidence-based guidelines on prevention and treatment guidelines for ALL-related VTE are lacking, and carefully designed clinical trials are needed urgently.

Management of occlusion and thrombosis associated with long-term indwelling central venous catheters

Long-term central venous catheters (CVCs) are important instruments in the care of patients with chronic illnesses, but catheter occlusions and catheter-related thromboses are common complications that can result from their use. In this Review, we summarise management of these complications. Mechanical CVC occlusions need cause-specific treatment, whereas thrombotic occlusions usually resolve with thrombolytic treatment, such as alteplase. Prophylaxis with thrombolytic flushes might prevent CVC infections and catheter-related thromboses, but confirmatory studies and cost-effectiveness analysis of this approach are needed. Risk factors for catheter-related thromboses include previous catheter infections, malposition of the catheter tip, and prothrombotic states. Catheter-related thromboses can lead to catheter infection, pulmonary embolism, and post-thrombotic syndrome. Catheter-related thromboses are usually diagnosed by Doppler ultrasonography or venography and treated with anticoagulation therapy for 6 weeks to a year, dependent on the extent of the thrombus, response to initial therapy, and whether thrombophilic factors persist. Prevention of catheter-related thromboses includes proper positioning of the CVC and prevention of infections; anticoagulation prophylaxis is not currently recommended.

Thrombolysis for intravascular thrombosis in neonates and children

PURPOSE OF REVIEW

Plasminogen activators stimulate the fibrinolytic pathway to accelerate thrombus resolution and can be used to treat serious and life-threatening arterial and venous thrombosis in neonates and children. The main disadvantage of these drugs is the risk of bleeding associated with their use. This article reviews the fibrinolytic pathway and discusses the current agents available for thrombolytic therapy, as well as indications for their use, dosing regimens, safety, and efficacy.

RECENT FINDINGS

There is great variation in the drug dosing regimens used for thrombolysis and in the incidence of bleeding complications that have been reported in pediatric series. Increased experience with these drugs, appropriate patient selection, and careful monitoring appear to have reduced the risk of major bleeding over time. The use of thrombolysis for occlusive deep vein thrombosis, in attempt to reduce the long-term complication of postthrombotic syndrome, is controversial and deserves further investigation.

SUMMARY

The use of thrombolytic therapy in pediatrics has increased over the past two decades. Urokinase and recombinant tissue plasminogen activator are the currently available thrombolytic agents. Catheter-related arterial thrombi that threaten life, organ or limb are the most common indication for their use. There is a tremendous need for well designed clinical studies to improve the safety and efficacy of these drugs in neonates and children.

Influence of the factor II G20210A variant or the factor V G1691A mutation on symptomatic recurrent venous thromboembolism in children: an international multicenter cohort study

OBJECTIVE

To determine the relative importance of the factor (F) II G20210A or FV G1691A mutations as risk factors or predictors for fatal/non-fatal recurrent venous thromboembolism (VTE) in children.

METHODS

In the present cohort, the rate of VTE recurrence and the time to recurrence in relation to FII, FV, age, and sex was determined in consecutively enrolled patients with VTE aged newborn to

RESULTS

Of the 416 children enrolled, 44 had recurrent VTE at a median of 12 months following VTE onset. The overall incidence rate of recurrence was 19.8, 57.9 in patients with the FII variant, 17.9 for FV carriers, and 11.8 in the control cohort. When comparing FII patients, FV children and the control cohort multivariate analysis (Cox regression) adjusted for age and sex showed that the FII variant (hazard ratio 2.6; 95% confidence interval 1.1-5.9) influenced the hazard for recurrent VTE.

CONCLUSIONS

Based on multivariate analysis, the presence of the FII variant was associated with an increased risk of VTE recurrence.

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MESH Headings

• Adolescent
• Age Factors
• Child
• Child, Preschool
• Cohort Studies
• Factor V/genetics
• Female
• Global Health
• Humans
• Infant
• Infant, Newborn
• Male
• Point Mutation
• Polymorphism, Single Nucleotide
• Prothrombin/genetics
• Recurrence
• Sex Factors
• Venous Thromboembolism/genetics

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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.

Anti-Xa Stability of Diluted Dalteparin for Pediatric Use

BACKGROUND:

The low-molecular-weight heparin (LMWH) dalteparin is approved by the Food and Drug Administration for prophylaxis of venous thromboembolism (VTE) in adults and has recently received an indication for acute VTE therapy in adults with cancer. Published reports of experience with dalteparin use in European children suggest that this LMWH agent is safe and effective in the prophylaxis and treatment of VTE in the pediatric population. However, dalteparin is commonly available in the US in a concentrated form that requires dilution for accurate administration in infants and young children.

OBJECTIVE:

To investigate the in vitro stability of diluted dalteparin for pediatric use, as measured by serial anti-Xa activity assays over the course of 4 weeks.

METHODS:

At 2 clinical research pharmacies, dalteparin multidose vials (anti-Xa concentration 25,000 U/mL) of the 2 distinct lots presently available for clinical use were diluted 1:10 with preservative-free NaCl 0.9% and maintained in tuberculin syringes at 4 °C. Syringes were then sampled for anti-Xa activity by chromogenic assay at baseline and weekly over the course of 4 weeks.

RESULTS:

For each lot of dalteparin, there was strong agreement in anti-Xa activity between corresponding diluted syringes prepared at the 2 pharmacy sites. No statistically significant difference in anti-Xa activity was detected from baseline to any time point, nor was a trend of change detected in anti-Xa activity with time for either lot of dalteparin.

CONCLUSIONS:

These data indicate that the anti-Xa activity of diluted dalteparin for pediatric use is stable over the course of 4 weeks.

Thrombophilia states and markers of coagulation activation in the prediction of pediatric venous thromboembolic outcomes: a comparative analysis with respect to adult evidence

Venous thromboembolism (VTE) in children is an important clinical concern for which risk factors include clinical conditions that incite venous stasis, endothelial damage, or thrombophilia (i.e., hypercoagulability) states. Acquired thrombophilia and markers of coagulation activation are common in pediatric VTE, while potent genetic thrombophilia states are less frequently encountered; nevertheless, the latter are more likely to present in the pediatric age than in older adulthood. Sequelae of VTE and its treatment in childhood survivors include bleeding, persistent or progressive thrombosis, recurrent VTE, and (when venous return from a limb is affected) the development of post-thrombotic syndrome (PTS). The focus of the present review is to discuss the role of tests of thrombophilia and coagulation activation as key predictors of outcome in this disease. Based upon this understanding, coupled with existing knowledge of clinical prognostic factors, new risk-stratified approaches of antithrombotic therapy have emerged for clinical investigation in the field of pediatric VTE.

Help me, Doctor! My D-dimer is raised

Although optimal strategy for management of patients with suspected venous thromboembolism depends on local expertise and cost, diagnostic algorithms including clinical assessment and D-dimer have been validated in several trials. However, a new paradigm shift is emerging, giving an extended role of D-dimer measurement in clinical practice. D-dimer is a useful biomarker to help determine initial anticoagulant therapy in patients with thrombosis. Emerging evidence also endorses a 'predictive' role for raised D-dimer levels, since its measurement provides prognostic indications for a variety of conditions, including venous thromboembolism, disseminated intravascular coagulation, cardiovascular disease, infectious diseases, and cancer. Additional investigation is needed to clarify whether raised D-dimer is an epiphenomenon or it is actively involved in pathophysiology. Further studies are also required to establish whether D-dimer testing, alone or combined with other prognostic indicators, can be used to identify patient candidates for further triage and treatment. Nevertheless, the hazard(s) associated with raised D-dimer in plasma requires re-emphasis in the teaching of post-graduates, junior doctors and medical students, including the most effective treatments to inhibit clot spread and decrease the probability of further significant thrombotic incidents even in the absence of any 'detectable' thrombosis.

Renal Vein Thrombosis

OBJECTIVE

The aim of this article is to review the published English literature on aetiology, pathology, clinical presentation, diagnostic methods and treatment of renal vein thrombosis.

MATERIALS AND METHODS

We searched the published literature from Medline & Pubmed using keywords renal vein thrombosis, anti-phospholipid syndrome and nephrotic syndrome. Data was extracted from individual case reports, case series, articles on pathology, diagnostic tests, treatment modalities, and previous reviews. Case reports which did not add any new information were excluded.

RESULTS

We selected 60 references based on the above criteria. Renal vein thrombosis is relatively rare. CT angiography is considered the investigation of choice. Alternatives include MR angiography or renal venography in highly selected patients. As the condition is relatively uncommon, consensus on the best form of therapy for this condition has been slow to evolve. The trend in management has shifted to non-surgical therapies particularly systemic anticoagulation except in highly selected group of patients.

Venous thromboembolism in the neonatal period

Thromboembolism occurs more frequently in newborns than in older infants or children. The developing hemostasis system of neonates has decreased concentrations of procoagulant proteins and the naturally occurring anticoagulants and hemostatic control proteins. Overall, neonatal hemostasis provides protection from excessive bleeding at the expense of an increased risk for thromboembolism. Intensive medical care for premature and ill infants often requires central vascular assess, and the most frequent risk factor for thromboembolism is the presence of an indwelling vascular catheter. Management of venous thromboembolism in the newborn period varies depending on the location and extent of the thrombus as well as the risk for acute embolic complications and later vascular compromise. Therapeutic decisions are guided by practitioners' past experience, published case reports and case series, several large registries, and extrapolation from results of clinical trials in adults with thromboembolic disease. Valuable consensus guidelines have been compiled by the AACP Conference on Antithrombotic and Thrombolytic Therapy. Heparin, either unfractionated or a low molecular weight preparation, is the most commonly utilized anticoagulant to treat thromboembolism in newborn infants. Thrombolytic therapy may be considered if the thrombus is life or limb threatening and there is no hemorrhagic contraindication. Multicenter, prospective, controlled clinical trials in this important patient population are needed to provide evidence-based data to better inform optimal management.

A thrombolytic regimen for high-risk deep venous thrombosis may substantially reduce the risk of postthrombotic syndrome in children

Important predictors of adverse outcomes of thrombosis in children, including postthrombotic syndrome (PTS), have recently been identified. Given this knowledge and the encouraging preliminary pediatric experience with systemic thrombolysis, we sought to retrospectively analyze our institutional experience with a thrombolytic regimen versus standard anticoagulation for acute, occlusive deep venous thrombosis (DVT) of the proximal lower extremities in children in whom plasma factor VIII activity and/or D-dimer concentration were elevated at diagnosis, from within a longitudinal pediatric cohort. Nine children who underwent the thrombolytic regimen and 13 who received standard anticoagulation alone were followed from time of diagnosis with serial clinical evaluation and standardized PTS outcome assessments conducted in uniform fashion. The thrombolytic regimen was associated with a markedly decreased odds of PTS at 18 to 24 months compared with standard anticoagulation alone, which persisted after adjustment for significant covariates of age and lag time to therapy (odds ratio [OR] = 0.018, 95% confidence interval [CI] = < 0.001-0.483; P = .02). Major bleeding developed in 1 child, clinically judged as not directly related to thrombolysis for DVT. These findings suggest that the use of a thrombolysis regimen may safely and substantially reduce the risk of PTS in children with occlusive lower-extremity acute DVT, providing the basis for a future clinical trial.

[Diagnosis and treatment of thromboembolic events in pediatrics]

Thromboembolic events are an increasingly commonly recognized secondary complications in children treated for serious, life-threatening primary diseases. Nevertheless the incidence of venous thromboembolic disease remains 100 times less frequent in hospitalized children than hospitalized adults, as recent data suggest an incidence of 5,3/10.000 pediatric patients compared to an incidence of 2,5-5/100 in adult patients. Diseases usually associated with thromboembolic events in children are neoplasia, autoimmune or cardiac malformative disease. Contrarily to what is observed in the adult, the majority of deep vein thrombosis events occur at the upper limbs veins, usually at the place where devices for venous access like port-a-cath or central venous lines are inserted. Because of the relatively low incidence of venous thromboembolic events in children, the diagnostic approach used are largely extrapolated from guidelines obtained from adult studies. However, the diagnostic performances of some diagnostic tools like Doppler-Ultrasound are probably diminished in children. Moreover, the concept of developmental hemostasis, which stresses the point that the hemostatic system in children is quite different from the adult one, is widely accepted and clearly suggests that the diagnostic and therapeutic approach in pediatric patients may not be simply extrapolated from data obtained in adult studies. From a more practical point of view, the fact that the hemostatic system in children is a dynamic and evolving system, renders the therapeutic approach quite complex. In particular, doses of anticoagulants vary markedly across the pediatric age. The absence of adapted formulations of commonly used anticoagulants, for example the absence of liquid formulations of anti-vitamin K drugs, further complicates the administration and the correct monitoring of anticoagulation in children, and may diminish observance in adolescent patients. Even though the concept that "children are not little adults" is nowadays widely accepted, there is an urgent need for prospective studies to better assess the modalities of diagnosis and treatment of venous thromboembolic disease in this particular population.

Lemierre's and Lemierre's-like syndromes in children: survival and thromboembolic outcomes

OBJECTIVE

Lemierre's syndrome, or jugular vein thrombosis (JVT) associated with anaerobic infection of the head and neck and frequently complicated by septic pulmonary embolism (PE), has historically been described as a disease of young adults. In recent years, an increasing number of case reports of childhood Lemierre's syndrome have been published, focusing mostly on the clinical and laboratory findings at disease presentation and the outcomes of infection. Given the potentially life-threatening thromboembolic complications of this disorder, we reviewed our single-institutional experience with pediatric Lemierre's and Lemierre's-like syndromes (LALLS) from within the context of a larger cohort study of thrombosis in children.

METHODS

Children who were aged from birth to 21 years and had received a diagnosis of JVT and Lemierre's syndrome at the Children's Hospital (Denver, CO) between 2001 and 2005 were identified for inclusion. Case designation of LALLS required all the following: (1) radiologic confirmation of JVT, (2) clinical diagnosis of pharyngitis or other febrile illness, and (3) intraoperative evidence of loculated infection in the head and neck region or radiologic demonstration of bilateral pulmonary infiltrates. Isolation of a causative organism by microbiologic culture of blood, tissue, or purulent fluid was also a necessary diagnostic criterion among patients who had not been treated with antibiotics before culture. A designation of classic Lemierre's syndrome was reserved for documented cases of anaerobic infection. Children in whom JVT was associated with the presence of an ipsilateral central venous catheter were excluded from the analysis. Analysis included information on underlying medical conditions, microbiologic and radiologic findings, and comprehensive hypercoagulability testing results from the time of diagnosis, as well as antimicrobial and anticoagulant therapies administered. In addition, clinical outcomes were evaluated via serial follow-up and included bleeding complications, thrombus resolution on serial radiologic studies, symptomatic recurrent venous thromboembolism (VTE), and mortality.

RESULTS

From January 2001 to January 2005, 9 children with LALLS were identified. Median age was 15 years (range: 2.5-20 years). Clinical presentation was consistent with septic PE in 5 cases and septic shock in 2. Thrombophilia was present in 100% (7 of 7) of children tested, consisting principally of antiphospholipid antibodies and elevated factor VIII activity. Anticoagulation was given in 89% (8 of 9), for a median duration of 3 months (range: 7 weeks-1 year). After a median follow-up time of 1 year, all children had survived without recurrent VTE or anticoagulant-associated major hemorrhage. JVT failed to resolve at 3 to 6 months in 38% of anticoagulated children.

CONCLUSIONS

Our experience suggests that LALLS is an emerging pediatric concern with serious acute (eg, septic PE) and chronic (eg, persistent vascular occlusion) complications. Septic JVT may not be uniquely anaerobic, and the inflammatory prothrombotic state is often characterized by antiphospholipid antibodies and elevated factor VIII levels. Early diagnosis and aggressive antimicrobial and antithrombotic therapies in LALLS may be necessary for optimal long-term outcomes.