Two-sample Fecal Immunochemical Testing as a Tool to avert Colonoscopy in Symptomatic Patients – A prospective multicenter cohort study

Background: In most colonoscopies performed for bowel symptoms, no significant lesions are found. To decrease the number of unnecessary colonoscopies, we evaluated the performance of two-sample fecal immunochemical testing (FIT) in ruling out significant lesions. Methods: Symptomatic patients referred for colonoscopy were instructed to perform two FITs from separate bowel-movements prior to colonoscopy. Colonoscopy and pathology data were collected. Two-sample FIT was considered positive when FIT1 and/or FIT2 was positive. Sensitivity and negative predictive value (NPV) for advanced neoplasia (AN), advanced serrated polyps and colitis were determined at different cut-off values. Results: 949 participants (median age 61 years, 50.6% male) from ten centers were included. Highest NPV and sensitivities were reached with two-sample FIT using the lowest limit of fecal-Hb detection (>1.7 µg/g). For AN this resulted in a NPV of 95.6% with a sensitivity of 71.7% and for CRC in a NPV of 99.7% with a sensitivity of 93.9%. Sensitivity for AN was higher (84.6%) in participants with alarm symptoms rectal bloodloss and/or anemia. NPV and sensitivity for IBD were 99.3% and 83.3%. 675 (71.1%) participants had concordant negative results. Conclusions: Two-sample FIT can achieve a NPV of 99.3% for IBD and 95.6% for AN with a sensitivity of 83.3% and 71.7% respectively. Concordant negative results were found in 71.1%. However, 28.3% of AN was still missed. Therefore, two-sample FIT may play a role in determining the need for colonoscopy in symptomatic patients, but it misses too many lesions to be used as the sole determinant to avert colonoscopy.

Publication History

Received: 26 September 2024

Accepted after revision: 06 July 2025

Accepted Manuscript online:
06 July 2025