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 results were positive. Sensitivity and negative predictive value (NPV) for advanced neoplasia, advanced serrated polyps, and colitis were determined at different cutoff values. Results: 949 patients (median age 61 years, 50.6% male) from 10 centers were included. The highest NPVs and sensitivities were reached with two-sample FIT using the lowest limit of fecal hemoglobin detection (>1.7 µg Hb/g). For advanced neoplasia and CRC, this resulted in NPVs of 95.6% and 99.7%, and sensitivities of 71.7% and 93.9%, respectively. Sensitivity for advanced neoplasia was higher (84.6%) in patients with the alarm symptoms of rectal blood loss and/or anemia. NPV and sensitivity for inflammatory bowel disease were 99.3% and 83.3%, respectively. Concordant negative results were found for 675 patients (71.1%). Conclusions: Despite a high NPV, two-sample FIT still missed 28.3% of advanced neoplasia. 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 for averting colonoscopy.