title: Using record linkage to monitor equity and variation in screening programmes.
abstract: BACKGROUND
  Ecological or survey based methods to investigate screening uptake rates are fraught with many limitations which can be circumvented by record linkage between Census and health services datasets using variations in breast screening attendance as an exemplar. The aim of this current study is to identify the demographic, socio-economic factors associated with uptake of breast screening.
  
  
  METHODS
  Record linkage study: combining 2001 Census data within the Northern Ireland Longitudinal Study (NILS) with data relating to validated breast screening histories from the National Breast Screening System. A cohort was identified of 37,059 women aged 48-64 at the Census who were invited for routine breast screening in the three years following the Census. All cohort attributes were as recorded on the Census form.
  
  
  RESULTS
  The record linkage methodology enabled the records of almost 40,000 of those invited for screening to be analysed at an individual level, exceeding the largest published survey by a factor of ten. This produced a more robust analysis and demonstrated (in fully adjusted models) the lower uptake amongst non-married women and those in the lowest social class (OR 0.74; 95%CI 0.66, 0.82), factors that had not been reported earlier in the UK. In addition, with the availability of both individual and area information it was possible to show that the much lower screening uptake in urban areas is not due to differences in population composition suggesting unrecognised organisational problems.
  
  
  CONCLUSIONS
  Linkage of screening data to Census-based longitudinal studies is an efficient and powerful way to increase the evidence base on sources of variation in screening uptake within the UK.
authors.affiliation: Centre for Public Health, Queen's University Belfast, Belfast, Northern Ireland.
authors.forename: Dermot
authors.initials: D
authors.lastname: O'Reilly
authors.forename: Heather
authors.initials: H
authors.lastname: Kinnear
authors.forename: Michael
authors.initials: M
authors.lastname: Rosato
authors.forename: Adrian
authors.initials: A
authors.lastname: Mairs
authors.forename: Clare
authors.initials: C
authors.lastname: Hall
mesh_terms: D001943:Breast Neoplasms / Q000175:diagnosis; D019352:Censuses; D055088:Early Detection of Cancer / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008498:Medical Record Linkage; D008875:Middle Aged; D015999:Multivariate Analysis; D009660:Northern Ireland; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data*; D011996:Records