Body mass index and thromboembolism in children with hematological malignancies

Incidence and risk factors for Central Nervous System thrombosis in paediatric acute lymphoblastic leukaemia during intensive asparaginase treatment: a single-centre cohort study

Central Nervous System (CNS) thrombosis is a complication of acute lymphoblastic leukaemia (ALL) treatment that is potentially associated with significant morbidity and neurological sequelae. Its presumably multifactorial aetiology is poorly characterized. We conducted a single-centre, retrospective cohort study on 346 ALL paediatric patients (1-16 years old) treated with asparaginase intensive Dana Farber Cancer Institute (DFCI) protocols from 1998 to 2011. The incidence, risk factors and outcome of CNS thrombosis were evaluated. CNS thrombosis occurred in 3·8% (13/346) of the patients (95% confidence interval 2·0-6·3%). Twelve events were diagnosed during intensification, all of which resolved within 2 weeks without neurological sequelae or significant impact in survival. Obesity (body mass index above 95th percentile) and asparaginase formulation were the only factors associated with CNS thrombosis, with an increase in the odds of event in obese patients [odds ratio (OR) = 3·37; P = 0·064] and a reduction in patients receiving Erwinia asparaginase (OR = 0·12; P = 0·018). No association could be demonstrated for age, gender, DFCI risk-group, ALL phenotype, steroid or doxorubicin use, central venous line use or CNS radiotherapy. CNS thrombosis is a rare but manageable adverse event without significant sequelae or detrimental effects in survival. Increased awareness is recommended in obese patients particularly during intensive asparaginase use.

The development of thromboembolism may increase the risk of osteonecrosis in children with acute lymphoblastic leukemia

Previous studies indicate pathophysiological and epidemiological parallels between osteonecrosis (ON) and thromboembolism (TE), two common treatment-related morbidities in acute lymphoblastic leukemia (ALL). To elucidate risk factors for ON and explore the relationship between ON and TE, we undertook a retrospective study of children (n = 208) with ALL. Twenty-one (10.1%) children developed ON and 42 (20.2%) TE on therapy. Thromboembolism was a significant predictor of ON on univariate (OR 8.85) and multivariate analysis, along with older age and PEGylated asparaginase. This observation supports a role for hypercoagulability in the pathogenesis of ON. Larger prospective studies are needed to further test these findings.

Impact of obesity on the risk of venous thromboembolism in an inpatient pediatric population

INTRODUCTION

The incidence of venous thromboembolism in children has increased significantly over the past 20 years. Over the same period of time, there was an increase in the prevalence of obesity in the pediatric population. Obesity is a known risk factor for VTE in adults, but little information is available in children.

METHODS

This study evaluates the relation between obesity and VTE using a retrospective, case-control design, comparing the body mass index (BMI) of patients admitted with a diagnosis of VTE versus patients admitted with other diagnoses, at a single institution, between 2007 and 2011.

RESULTS

We studied 48 inpatients diagnosed with deep venous thrombosis or pulmonary embolism and a control group of 274 age and gender matched patients admitted with other diagnoses. We found obese patients (BMI > 95th percentile) to have significantly higher risk of VTE (odds ratio 2.1, with 95% CI 1.1-4.2) than patients of normal weight (BMI < 85th percentile). Overweight patients (BMI 85th-95th percentile) did not demonstrate a significant change in risk. Most of the VTE patients were adolescents and the majority of them had other identifiable risk factors for thrombosis.

CONCLUSION

This study establishes a correlation between obesity and VTE in a group of hospitalized children, showing a risk for VTE in obese children similar to the one described in much larger adult cohorts.

Venous thromboembolism in children with cancer - a population-based cohort study

Introduction

Cancer is a known risk factor for venous thromboembolism (VTE) in adults, but population-based data in children are scarce.

Materials and methods

We conducted a cohort study utilising linkage of the Clinical Practice Research Database (primary care), Hospital Episodes Statistics (secondary care), UK Cancer Registry data and Office for National Statistics cause of death data. From these databases, we selected 498 children with cancer diagnosed between 1997 and 2006 and 20,810 controls without cancer. We calculated VTE incidence rates in children with cancer vs. controls, and hazard ratios (HRs) using Cox regression.

Results

We identified four VTE events in children with cancer compared with four events in the larger control population corresponding to absolute risks of 1.52 and 0.06 per 1000 person-years respectively. The four children with VTE and cancer were diagnosed with hematological, bone or non-specified cancer. Childhood cancer was hence associated with a highly increased risk of VTE (HR adjusted for age and sex: 28.3; 95%CI = 7.0-114.5).

Conclusions

Children with cancer are at increased relative risk of VTE compared to those without cancer. Physicians could consider thromboprophylaxis in children with cancer to reduce their excess risk of VTE however the absolute risk is extremely small and the benefit gained therefore would need to be balanced against the risk invoked of implementing such a strategy.

Novelty & Impact Statements

While there is a reasonable level of knowledge about the risk of VTE in adult populations, it is not well known whether this risk is reflected in paediatric patients. We found a substantial increase in risk of VTE in children with cancer compared to a child population without cancer. While this finding is important, the absolute risk of VTE is still low and must be balanced with the risks of anticoagulation.