title: Diagnostic inconsistency of faecal immunochemical tests for haemoglobin in population screening of colorectal cancer.
abstract: BACKGROUND
  There is currently very little data available on the consistency of quantitative and qualitative faecal immunochemical test (FIT) for colorectal cancer screening.
  
  
  METHODS
  A representative random population (n=1889, 40-74 year olds) in Jiashan, China was invited for FIT screening in 2012. Faecal samples were collected by a single specimen collection device and simultaneously tested by a quantitative FIT (OC-SENSOR, OC) and two qualitative FITs (FIT A and FIT B with intrinsic positive haemoglobin cut-off concentrations of 20 μg Hb/g faeces and 40 μg Hb/g faeces, respectively). The observational criteria for a positive result of the qualitative FIT were set according to the density of the colour appearing in the test strip. The results produced by the quantitative and qualitative FIT for each sample were compared. κ coefficient was used to measure consistency.
  
  
  RESULTS
  A total of 1368 (72.4%) individuals returned faecal samples. Both FIT A and FIT B precisely identified all faecal samples with haemoglobin concentration above 100 μg Hb/g faeces, but the overall consistency was poor for OC & FIT A (κ=0.32, 95% CI 0.20-0.44) and was moderate for OC & FIT B (κ=0.74, 95% CI 0.64-0.85). A more favourable consistency (κ=0.64, 95% CI 0.57-0.72) was achieved when a different positive criterion was employed for FIT A.
  
  
  CONCLUSIONS
  The diagnostic inconsistency between quantitative and qualitative FITs mainly exists in the faecal samples with low haemoglobin concentrations. Refining the criterion for a positive result may be a feasible way to improve the accuracy of qualitative FIT.
authors.forename: Yanqin
authors.initials: Y
authors.lastname: Huang
authors.forename: Weiting
authors.initials: W
authors.lastname: Ge
authors.forename: Viktoriya
authors.initials: V
authors.lastname: London
authors.forename: Qilong
authors.initials: Q
authors.lastname: Li
authors.forename: Shanrong
authors.initials: S
authors.lastname: Cai
authors.forename: Suzhan
authors.initials: S
authors.lastname: Zhang
authors.forename: Shu
authors.initials: S
authors.lastname: Zheng
mesh_terms: D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D005243:Feces / Q000737:chemistry*; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007120:Immunochemistry; D008403:Mass Screening; D008875:Middle Aged; D015203:Reproducibility of Results
chemical_list: D006454:Hemoglobins