title: Specific and Non-specific Clinical Presentations in the Year Before the Diagnosis of Childhood Leukaemia.
abstract: Clinical presentations of childhood leukaemia have been reported in case-only studies. The timing when these presentations start to occur prior to diagnosis is less clear.
  
  
  
  In this nested case-control study, 1,025 and 334 children with lymphoid and myeloid leukaemia, respectively, were matched (1:30) to population-based controls by sex, region and year of birth. An index date was assigned for each control when the matched case was diagnosed. Healthcare access records of cases and controls in the year before the index date were extracted.
  
  
  
  Children with lymphoid leukaemia started to visit doctors more often at least 2 months before leukaemia diagnosis (P < 0.05). Various presentations were recorded in these visits: rates of haematological presentations, musculoskeletal presentations, and injuries started to increase significantly at least 3 months before diagnosis; rates of respiratory, gastrointestinal and urinary tract presentations did not increase significantly until the last month. The findings for myeloid lymphoma were less clear, but children appeared to visit doctors more often at least 4 months before diagnosis, and the rate of haematological presentations also started to increase at least 4 months before leukaemia diagnosis. Although haematological presentations were most strongly associated with undiagnosed leukaemia (odds ratio > 290 in the last month), the majority (>96%) of children with haematological presentations did not have leukaemia if they had not been diagnosed in their first visit.
  
  
  
  We described a clinical picture in the year before leukaemia diagnosis. These findings revealed ongoing difficulties in early diagnosis of childhood leukaemia in healthcare settings.
authors.affiliation: Nuffield Department of Population Health, University of Oxford, Oxford, UK.
authors.forename: TienYu Owen
authors.initials: TO
authors.lastname: Yang
authors.affiliation: Department of Pediatrics, Taipei Medical University Hospital, Taipei City, Taiwan.|Ph.D. Program in Translational Medicine, National Taiwan University and Academia Sinica, Taipei, Taiwan.|Department of Pediatrics, National Taiwan University Hospital, Taipei City, Taiwan.
authors.forename: Yen-Lin
authors.initials: YL
authors.lastname: Liu
authors.affiliation: Office of Preventive Medicine, Taiwan Centers for Disease Control, Taipei City, Taiwan.
authors.forename: Wan-Ting
authors.initials: WT
authors.lastname: Huang
authors.affiliation: Department of Pediatrics, National Taiwan University Hospital, Yun-Lin Branch, Yunlin County, Taiwan.
authors.forename: Mei-Huei
authors.initials: MH
authors.lastname: Chen
authors.affiliation: Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei City, Taiwan.|Department of Public Health, College of Public Health, National Taiwan University, Taipei City, Taiwan.|Department of Environmental and Occupational Medicine, College of Medicine and Hospital, National Taiwan University, Taipei City, Taiwan.
authors.forename: Pau-Chung
authors.initials: PC
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005767:Gastrointestinal Diseases / Q000175:diagnosis*; D006801:Humans; D007945:Leukemia, Lymphoid / Q000175:diagnosis* / Q000473:pathology; D007951:Leukemia, Myeloid / Q000175:diagnosis* / Q000473:pathology; D008171:Lung Diseases / Q000175:diagnosis*; D012042:Registries; D013624:Taiwan; D014570:Urologic Diseases / Q000175:diagnosis*
keywords: cancer screening; childhood leukaemia; early diagnosis; electronic health record; epidemiology; personalised medicine