Result card

  • EFF30: What is known about the intra- and inter-observer variation in FIT interpretation?

What is known about the intra- and inter-observer variation in FIT interpretation?

Authors: Jesús González-Enríquez, Francesca Gillespie, Stefania Lopatriello, Iñaki Imaz

Internal reviewers: Pseudo125 Pseudo125

Please refer to EFF 20.

The development of automated systems for the interpretation of the test has increased the advantage of FITs. Accurate interpretation of gFOBTs is not easy and requires well-run laboratories. An automated FIT is easier to interpret, and minimizes human error in test processing, thus making it a more objective laboratory test with excellent quality control. Furthermore, it measures the concentration of hemoglobin in the buffer, thus making it possible to choose the cutoff value. It is also possible to reinterpret the test in case of a technical problem {19}.


Direct comparison between quantitative and qualitative immunochemical fecal occult blood tests (FOBTs) has been studied. One cohort study reported that quantitative FITs offers advantages in terms of transparency and flexibility regarding the positivity threshold (e.g., specificity can be oriented toward available colonoscopy resources or personal risk profiles) and in terms of a higher level of standardization regarding test analysis and interpretation {25}.


These findings are also confirmed by another cohort study that reported a positivity rates of 8.1% for the qualitative and 2.5% for the quantitative FIT. The detection rate was 5.2% for the qualitative and 14.4% for the quantitative FIT. The odds ratio of a “suspicious cancer and cancer” versus a “normal” result was 2.73 (95% CI=2.22–3.35) for the quantitative compared to qualitative FIT {33}.


Another study about inter-observer variability in interpretation of 5 visually read FOBTs methods (standard guaiac-based method and four immunochemical methods)  reported  no cases of observer variability except for Hemoccult ITC test this was only minimal (on 1 sample 2 observers recorded a faint band at the cut off and one called the test negative){31}. 

González-Enríquez J et al. Result Card EFF30 In: González-Enríquez J et al. Clinical Effectiveness In: Jefferson T, Cerbo M, Vicari N [eds.]. Fecal Immunochemical Test (FIT ) versus guaiac-based fecal occult blood test (FOBT) for colorectal cancer screening [Core HTA], Agenas - Agenzia nazionale per i servizi sanitari regionali; 2014. [cited 16 June 2021]. Available from: