Transition to quantitative faecal immunochemical testing from guaiac faecal occult blood testing in a fully rolled-out population-based national bowel screening programme

Abstract

ObjectiveFaecal immunochemical tests (FIT) are replacing guaiac faecal occult blood tests (FOBT) in colorectal cancer (CRC) screening. Data from the first year of FIT screening were compared with those from FOBT screening and assumptions based on a pilot evaluation of FIT.DesignData on uptake, positivity, positive predictive value (PPV) for CRC and higher-risk adenoma from participants in the first year of the FIT-based Scottish Bowel Screening Programme (n=919 665), with a threshold of 80 µg Hb/g faeces, were compared with those from the penultimate year of the FOBT-based programme (n=862 165) and those from the FIT evaluation (n=66 225).ResultsOverall, uptake of FIT was 63.9% compared with 56.4% for FOBT. Positivity was 3.1% and 2.2% with FIT and FOBT; increases were seen in both sexes, and across age range and deprivation. More CRC and adenomas were detected by FIT, but the PPV for CRC was less (5.2% with FIT and 6.4% with FOBT). However, for higher-risk adenoma, PPV was greater with FIT (24.3% with FIT and 19.3% with FOBT). In the previous FIT evaluation, uptake was 58.5% with FIT compared with 54.0% with FOBT; positivity was 2.5% with FIT and 2.0% with FOBT.ConclusionTransition to FIT from FOBT produced higher uptake and positivity with lower PPV for CRC and higher PPV for adenoma. The FIT pilot evaluation underestimated uptake and positivity. Introducing FIT at the same threshold as the evaluation caused a 67.2% increase in colonoscopy demand instead of a predicted 10%.

Adenoma detection rate in fecal immunochemical test positive colonoscopies: a population-based observational study

“…The overall ADR in FIT-positive colonoscopies was 57.6% in this study, higher than ADRs reported in other FIT screening programs (43.5% to 51.5%), 15,16,26 largely higher than those observed in gFOBT (35% to 47%) 26,27 and colonoscopy screening programs (20% to 25%). 7,28 However, dramatic inter-endoscopist variation in adenoma detection and characterization were observed in our organized screening program supposed to offer to all invited persons an equally high-quality service.…”

Faecal haemoglobin distributions by sex, age, deprivation and geographical region: consequences for colorectal cancer screening strategies

“…The f-Hb is higher in both men and women in all age groups in the SBoSP: this explains the higher overall positivity than that found in the FFLT pilot evaluation. (19) There are several plausible reasons for the discrepancies. Firstly, the quantitative FIT system used in the SBoSP (HM-JACKarc, Hitachi Chemical Diagnostic Systems Co., Ltd, Tokyo, Japan) differs from that used in the FFLT (OC-Sensor Diana, Eiken Chemical Co., Ltd, Tokyo, Japan).…”

“…(18) In November 2017, the SBoSP evolved to use quantitative FIT as the primary screening test. (19) We have here generated the f-Hb distributions by sex, age, deprivation in detail and, for the first time, geographical region, derived from the data generated from a screening population of almost one million participants. We have examined the implications for screening, reference values, the use of stratified f-Hb thresholds and the creation and application of risk scores.…”

Screening and prevention of colorectal cancer

“…A study from Scotland compared initiating a FIT screening program with a participation rate of 63% for FIT compared with 56% for FOBT. 143 A prior study evaluating the role of small value financial incentives failed to show increased participation in FIT screening. 144 Adherence to colonoscopy was lower, but increased participation was noted when patients were offered both stool-based and colonoscopy screening as options.…”