title: Venous thromboembolism occurring during adolescence.
abstract: OBJECTIVE
  Risk assessment for venous thromboembolism (VTE) and thromboprophylaxis in those with risk factors is established in adult practice. Evidence to support efficacy and safety of this approach in adolescents is lacking. We aimed to describe thrombotic risk factors and to determine the proportion of potentially preventable events in a retrospective cohort study of adolescents with VTE.
  
  
  METHODS
  Data were collected between 2008 and 2014 from eight tertiary UK centres. Qualifying events were radiologically confirmed VTE in subjects aged 12-17 years. Central venous line-related upper venous system events were excluded.
  
  
  RESULTS
  76 cases were identified, 41 males, median age 15 years. Frequent risk factors were: reduced mobility, 45%; thrombophilia, 24%; malignancy, 20%; surgery, 18%; combined oral contraceptive pill, 12%; congenital venous anomaly, 5%. 28 (37%) had no significant underlying diagnosis and no provoking event/hospitalisation, presenting as outpatients with VTE which was considered 'unpreventable'. Of 48 where there had been opportunity for risk assessment, chemical thromboprophylaxis was not indicated in 26 and was contraindicated in 8. 14/76 (18%) had an indication to consider thromboprophylaxis and no contraindication. Of these, four had cerebral palsy, five malignancy and two inflammatory bowel disease. All had reduced mobility with recent surgery in eight. Four received chemical thromboprophylaxis prior to presentation.
  
  
  CONCLUSIONS
  Among a cohort of adolescents with VTE, a small proportion (13%) had an indication to consider chemical thromboprophylaxis but did not receive it. VTE risk assessment and prevention should focus on adolescents with immobility or surgery, particularly in those with malignancy.
authors.affiliation: Department of Haematology, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK.
authors.forename: Tina
authors.initials: T
authors.lastname: Biss
authors.affiliation: Haemophilia and Thrombosis Centre, University Hospital of Wales, Cardiff, UK.
authors.forename: Raza
authors.initials: R
authors.lastname: Alikhan
authors.affiliation: Department of Haematology, Sheffield Children's Hospital, Sheffield, UK.
authors.forename: Jeanette
authors.initials: J
authors.lastname: Payne
authors.affiliation: Department of Haematology, Evelina London Children's Hospital, London, UK.
authors.forename: Jayanthi
authors.initials: J
authors.lastname: Alamelu
authors.affiliation: Department of Haematology, Birmingham Children's Hospital NHS Trust, Birmingham, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Williams
authors.affiliation: Department of Paediatric Haematology, Leeds Children's Hospital, Leeds, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Richards
authors.affiliation: Haematology Department, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK.
authors.forename: Mary
authors.initials: M
authors.lastname: Mathias
authors.affiliation: Department of Haematology, The University Hospitals Bristol NHS Trust, Bristol, UK.
authors.forename: Oliver
authors.initials: O
authors.lastname: Tunstall
authors.affiliation: Department of Haematology, Royal Hospital for Children, Glasgow, UK.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Chalmers
mesh_terms: D000293:Adolescent; D000925:Anticoagulants / Q000627:therapeutic use; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D006113:United Kingdom; D054556:Venous Thromboembolism / Q000209:etiology* / Q000517:prevention & control
chemical_list: D000925:Anticoagulants
keywords: Adolescent Health; Haematology; Thromboprophylaxis; Thrombosis