title: Evidence for under-diagnosis of childhood acute lymphoblastic leukaemia in poorer communities within Great Britain.
abstract: BACKGROUND
  Recorded incidence of childhood acute lymphoblastic leukaemia tends to be lower in poorer communities. A 'preemptive infection hypothesis' proposes that some children with leukaemia die from infection without diagnosis of leukaemia. Various different blood abnormalities can occur in untreated leukaemia.
  
  
  METHODS
  Logistic regression was used to compare pre-treatment blood counts among children aged 1-13 years at recruitment to national clinical trials for acute lymphoblastic leukaemia during 1980-2002 (N=5601), grouped by address at diagnosis within Great Britain into quintiles of the 1991 Carstairs deprivation index. Children combining severe neutropenia (risk of serious infection) with relatively normal haemoglobin and platelet counts (lack of pallor and bleeding) were postulated to be at risk of dying from infection without leukaemia being suspected. A deficit of these children among diagnosed patients from poorer communities was predicted.
  
  
  RESULTS
  As predicted, there was a deficit of children at risk of non-diagnosis (two-sided P(trend)=0.004; N=2009), and an excess of children with pallor (P(trend)=0.045; N=5535) and bleeding (P(trend)=0.036; N=5541), among cases from poorer communities.
  
  
  CONCLUSIONS
  Under-diagnosis in poorer communities may have contributed to socioeconomic variation in recorded childhood acute lymphoblastic leukaemia incidence within Great Britain, and elsewhere. Implications for clinical practice and epidemiological studies should be considered.
authors.affiliation: Childhood Cancer Research Group, Department of Paediatrics, University of Oxford, UK. mary.kroll@ceu.ox.ac.uk
authors.forename: M E
authors.initials: ME
authors.lastname: Kroll
authors.forename: C A
authors.initials: CA
authors.lastname: Stiller
authors.forename: S
authors.initials: S
authors.lastname: Richards
authors.forename: C
authors.initials: C
authors.lastname: Mitchell
authors.forename: L M
authors.initials: LM
authors.lastname: Carpenter
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002986:Clinical Trials as Topic; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D011203:Poverty / Q000706:statistics & numerical data*; D017410:Practice Guidelines as Topic / Q000592:standards*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000175:diagnosis* / Q000453:epidemiology; D011379:Prognosis; D006113:United Kingdom / Q000453:epidemiology