THE CHANGE FROM GUAIAC TO IMMUNOCHEMICAL FAECAL TEST LEADS TO INCREASED ADENOMA DETECTION RATES IN A REGIONAL COLORECTAL SCREENING PROGRAM

Aims To compare the trends of adenoma and carcinoma detection rates in a regional colorectal screening program after the change from guaiac to faecal immunochemical test (FIT).

Methods Prospective cohort study of asymptomatic patients with positive faecal blood test that underwent a screening colonoscopy in a referral unit in Portugal Centre region. Two groups - Guaiac, in use until 2018; FIT in use since 2019. Recorded data from colonoscopies from 2018 and 2019, demographics, quality colonoscopy metrics, polyp (PDR), adenoma (ADR), advanced ADR and carcinoma detection rates. Statistical analysis with Qui² and t-test.

Results 767 patients, 384 in Guaiac and 383 in FIT group. The groups were similar regarding mean age (62.1 vs. 62.9 years, p=0.13), sex (male: 50% vs. 55%, p=0.16) and characteristics for possible inadequate bowel preparation. Comparing Guaiac vs. FIT, the PDR was 46.9% vs. 58.2% (p=0.002, OR 1.6, 95%CI 1.2-2.1), the mean polyp per procedure was 1.1 vs. 1.9 (p< 0.001) and the ADR was 35.7% vs. 45.7% (p=0.005, OR 1.5, 95%CI 1.1-2); overall, per sex, ADR in female was 31% (26% vs. 37%) and 49.4% in men (45% vs. 53%). Still comparing Guaiac vs. FIT, the advanced ADR was 14% vs. 24% (p< 0.001, OR 1.9, 95%CI 1.3-2.8), the carcinoma detection was 2.1% vs. 4.4%, p=0.07); the mean lesion size increased (7mm vs. 8.7mm, p=0.001) and the resection of >20mm lesions also increased (2.3% vs 5.4%, p=0.053). No differences (Guaiac vs. FIT) were found in bowel preparation (91.5% vs. 91.6%, p=0.9), cecal intubation rate (98.1% vs. 95.3%, p=0.59), withdrawal time (8.1 vs. 8.4 minutes, p=0.38) and complications (0.5% vs. 1.1%, p=0.39).

Conclusions The shift for a FIT-based program allows a better screening and an increase in health gain, by improving the lesions’ detection and removal of premalignant lesions.