title: Venous thromboembolism in children with cancer - a population-based cohort study.
abstract: BACKGROUND
  Cancer is a known risk factor for venous thromboembolism (VTE) in adults, but population-based data in children are scarce.
  
  
  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.
  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.
authors.affiliation: Division of Epidemiology and Public Health, University of Nottingham, Nottingham City Hospital, NG5 1PB UK; Nottingham Digestive Diseases Centre, NIHR Biomedical Research Unit. Electronic address: alex.walker@nottingham.ac.uk.
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Walker
authors.affiliation: Division of Epidemiology and Public Health, University of Nottingham, Nottingham City Hospital, NG5 1PB UK; Nottingham Digestive Diseases Centre, NIHR Biomedical Research Unit.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Grainge
authors.affiliation: Division of Epidemiology and Public Health, University of Nottingham, Nottingham City Hospital, NG5 1PB UK; Nottingham Digestive Diseases Centre, NIHR Biomedical Research Unit.
authors.forename: Tim R
authors.initials: TR
authors.lastname: Card
authors.affiliation: Division of Epidemiology and Public Health, University of Nottingham, Nottingham City Hospital, NG5 1PB UK; Nottingham Digestive Diseases Centre, NIHR Biomedical Research Unit.
authors.forename: Joe
authors.initials: J
authors.lastname: West
authors.affiliation: Childhood Cancer Research Unit, Karolinska Institutet Stockholm Sweden.
authors.forename: Susanna
authors.initials: S
authors.lastname: Ranta
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet Sockholm Sweden; Department of Pediatrics, Örebro University Hospital, Örebro University, Örebro Sweden.
authors.forename: Jonas F
authors.initials: JF
authors.lastname: Ludvigsson
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000097:blood* / Q000453:epidemiology* / Q000473:pathology; D012307:Risk Factors; D013923:Thromboembolism / Q000097:blood / Q000453:epidemiology* / Q000473:pathology; D006113:United Kingdom / Q000453:epidemiology; D054556:Venous Thromboembolism / Q000097:blood / Q000453:epidemiology* / Q000473:pathology
keywords: Cancer; Children; Malignancy; Thromboembolism; Venous thrombosis