title: Patterns of uptake in a biennial faecal occult blood test screening programme for colorectal cancer.
abstract: OBJECTIVE
  The patterns of response in faecal occult blood test (FOBT) screening were studied.
  
  
  METHODS
  A total of 251,578 people invited three times for faecal occult blood testing were categorized according to how they responded to the invitations, as follows: YNN, NYN, NNY, NYY, YNY, YYN, YYY or NNN (Y = response; N = no response).
  
  
  RESULTS
  Overall, 163,038 (64.8%) responded at least once, and of those the biggest category was YYY (98,494, 60.4%). Of 1927 cancers diagnosed in the age group eligible for screening, there were 405 screen-detected cancers, 529 interval cancers and 993 cancers arising in people who had not been screened for over 2 years (i.e. falling outside the interval cancer category). In the YYY group, 79 screen-detected cancers would have been missed had the members of this group responded YNN and 65 had they responded YYN. In the YYN group, 104 screening cancers would have been missed if they had followed the YNN pattern. In most cases, the screen-detected cancers were diagnosed at the last invitation accepted, indicating that, after a diagnosis of cancer, further screening invitations were rarely accepted. Accordingly, the numbers of screen-detected and interval cancers were adjusted for likely pattern of response according to the proportion of the whole population falling into each pattern. With this adjustment, 40.9% of the cancers in the YYY group were screen detected compared with 29.3% in the YYN group and 20.7% in the YNN group (P < 0.001). Among those who responded once, twice and three times, the stage distribution of screen-detected cancers was similar, indicating that the prognosis of screen-detected cancer is unlikely to be poorer if not detected at the first screen.
  
  
  CONCLUSIONS
  This study is the first to examine patterns of response to screening invitations and confirms the importance to individuals of continuing to accept repeated screening invitations.
authors.affiliation: Department of Surgery, University of Dundee, Dundee, UK; Scottish Bowel Screening Centre, Dundee, UK; Bowel Screening Research Unit, Scottish Bowel Screening Centre, Dundee, UK.
authors.forename: R J C
authors.initials: RJ
authors.lastname: Steele
authors.forename: P L
authors.initials: PL
authors.lastname: McClements
authors.forename: G
authors.initials: G
authors.lastname: Libby
authors.forename: F A
authors.initials: FA
authors.lastname: Carey
authors.forename: C G
authors.initials: CG
authors.lastname: Fraser
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000473:pathology; D055088:Early Detection of Cancer / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009780:Occult Blood; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data*
keywords: Colorectal cancer screening; faecal occult bleed test; screening uptake