Repeat FIT Offers Greater Differentiation of Patients With, Without Significant Pathology

The likelihood of detecting colorectal cancer (CRC) or significant bowel disease (SBD) increases with repeated fecal immunochemical tests (FIT), according to study results published online ahead of print in Colorectal Disease.

“Repeat FIT can differentiate those most at risk of significant pathology whilst simultaneously offering further reassurance to those patients with negative FIT,” wrote corresponding author Nicholas G. Farkas, MBBS, clinical research fellow at Royal Surrey County Hospital NHS Foundation Trust, Guildford, England, and study coauthors.

The prospective observational study investigated the value of a second and third FIT in 460 patients with suspected CRC or SBD who also underwent colonoscopy. Researchers calculated diagnostic accuracy variables, such as sensitivity, specificity, positive predictive value, and negative predictive value, for 1, 2, and 3 FIT.

Sensitivity for CRC remained static (95.7%) with 1, 2, and 3 negative FIT, according to the study. Specificity and negative predictive value decreased. Specificity lessened from 44.6% with 1 to 40.7% with 2 and 38.4% with 3 FIT, while negative predictive value decreased from 99.5% with 1 to 99.4% with 2 and 3 FIT.

Sensitivity for SBD increased from 78.8% with 1 to 83.8% with 2 and 86.3% with 3 FIT, the study found. Specificity decreased from 47.4% with 1 to 43.7% with 2 and 41.6% with 3 FIT. Negative predictive value increased from 91.4% with 1 to 92.7% with 2 and 93.5% with 3 FIT.

“A repeat FIT strategy offered greater differentiation and improves detection rates when compared to a 1 FIT strategy,” researchers reported. “For CRC, 1 FIT had an 8.3% detection rate in the positive FIT group (95% CI: 7.5–9.3) whereas the 2 and 3 positive FIT groups had 16.1% (95% CI [confidence interval]: 12.9–19.9) and 20.9% (95% CI: 16.3–26.5) rates, respectively. A similar trend was observed for SBD.”

Reference

Farkas NG, Palyvos L, O'Brien JW, et al. The repeat FIT (RFIT) study: does repeating faecal immunochemical tests provide reassurance and improve colorectal cancer detection? Colorectal Dis. Published online August 13, 2024. doi:10.1111/codi.17132