Result card

  • TEC18: Are the reference values or cut-off points clearly established?
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Are the reference values or cut-off points clearly established?

Authors: Mirjana Huic, Eleftheria Karampli, Silvia Florescu, Cristian Vladescu

Internal reviewers: Antonio Migliore, Pernilla Östlund, Frida Mowafi, Daniela d’Angela, Jesus Gonzalez

Results {5-8,20}

Cut-off limits are important in CRC screening due the fact that, by increasing the positive cut-off limit, the test sensitivity and positivity rate decreases and specificity and positive predictive values for CRC detection increase.

European guidelines {6} state that “the choice of a cut-off concentration to be used in an immunochemical test to discriminate between a positive and negative result will depend on the test device chosen, the number of samples used and the algorithm adopted to integrate the individual test results. Whilst an increasing number of studies are reporting the experience of different algorithms, local conditions, including the effect on sample stability of transport conditions, preclude a simple prescribed algorithm at this time. Adoption of a test device and the selection of a cut-off concentration should follow a local pilot study to ensure that the chosen test, test algorithm and transport arrangements work together to provide a positivity rate that is clinically, logistically and financially acceptable (VI - A)”.

Two out of three iFOBT are quantitative tests and have adjustable or user defined cut-off values (OC-Sensor and The FOB Gold); Hem-SP/MagStream HT is qualitative, and has a non-adjustable cut-off value:

  • OC-Sensor is CE marked for a user defined cut-off (default setting 100 ng/mL), with 20 ng/mL in buffer as limit of detection.;
  • Hem-SP/MagStream HT is qualitative, and has a non-adjustable cut-off at a Hb concentration equal to or greater than 20 ng/ml;
  • The FOB Gold is CE marked for a user defined cut-off, with limit of detection of 14 ng/mL buffer, and measuring range of 15-1000 ng/ml.

 

Van Rossum at al. {20}, using OC-Sensor collection and OC-Micro analyser  concluded that cut-off of 75 ng/ml brought optimal results and may be recommended for population screening in Netherlands. They concluded also in settings where colonoscopy capacity is insufficient, a cut-off up to 200ng/ml would result in minimal false negative results for cancer although more for advance adenoma.

 

Critical
Completely
Huic M et al. Result Card TEC18 In: Huic M et al. Description and technical characteristics of technology 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: http://corehta.info/ViewCover.aspx?id=206

References