title: Test, episode, and programme sensitivities of screening for colorectal cancer as a public health policy in Finland: experimental design.
abstract: OBJECTIVE
  To report the sensitivities of the faecal occult blood test, screening episode, and screening programme for colorectal cancer and the benefits of applying a randomised design at the implementation phase of a new public health policy.
  
  
  METHODS
  Experimental design incorporated in public health evaluation using randomisation at individual level in the target population.
  
  
  METHODS
  161 of the 431 Finnish municipalities in 2004-6.
  
  
  METHODS
  106 000 adults randomised to screening or control arms. In total, 52 998 adults aged 60-64 in the screening arm received faecal occult blood test kits.
  
  
  METHODS
  Test, episode, and programme sensitivities estimated by the incidence method and corrected for selective attendance and overdiagnosis.
  
  
  RESULTS
  The response for screening was high overall (70.8%), and significantly better in women (78.1%) than in men (63.3%). The incidence of cancer in the controls was somewhat higher in men than in women (103 v 93 per 100 000 person years), which was not true for interval cancers (42 v 49 per 100 000 person years). The sensitivity of the faecal occult blood test was 54.6%. Only a few interval cancers were detected among those with positive test results, hence the episode sensitivity of 51.3% was close to the test sensitivity. At the population level the sensitivity of the programme was 37.5%.
  
  
  CONCLUSIONS
  Although relatively low, the sensitivity of screening for colorectal cancer with the faecal occult blood test in Finland was adequate. An experimental design is a prerequisite for evaluation of such a screening programme because the effectiveness of preventing deaths is likely to be small and results may otherwise remain inconclusive. Thus, screening for colorectal cancer using any primary test modality should be launched in a public health programme with randomisation of the target population at the implementation phase.
authors.affiliation: Finnish Cancer Registry, Pieni Roobertinkatu 9, 00130 Helsinki, Finland. nea.malila@cancer.fi
authors.forename: Nea
authors.initials: N
authors.lastname: Malila
authors.forename: Tiina
authors.initials: T
authors.lastname: Oivanen
authors.forename: Outi
authors.initials: O
authors.lastname: Malminiemi
authors.forename: Matti
authors.initials: M
authors.lastname: Hakama
mesh_terms: D015179:Colorectal Neoplasms / Q000517:prevention & control*; D005260:Female; D005387:Finland; D006801:Humans; D015994:Incidence; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D009780:Occult Blood; D012680:Sensitivity and Specificity