Effect of ulcerative colitis duration on the usefulness of immunochemical fecal occult blood test result as a disease activity biomarker.

PURPOSE The effects of ulcerative colitis (UC) duration on biomarker accuracy are unknown. We investigated the effects of UC duration on the predictive accuracy of biomarkers including immunochemical fecal occult blood test (FOBT, also known as FIT), prostaglandin E-major urinary metabolite (PGE-MUM), and C-reactive protein (CRP). METHODS We divided 133 samples into groups based on disease duration. Clinical and endoscopic remission was defined as Lichtiger's clinical activity index (CAI) of ≤ 4, Mayo endoscopic subscore (MES) of 0, and UC endoscopic index of severity (UCEIS) of ≤ 1. RESULTS FIT results were significantly correlated with all activity scores when the disease duration was < 4 years. When the disease duration was ≥ 4 years, FIT results were significantly correlated with the CAI and MES but not with UCEIS. When the disease duration was ≥ 5 years, FIT and CAI were significantly correlated, whereas FIT and MES or FIT and UCEIS did not show any correlation. When the duration was ≥ 4 years, PGE-MUM and CRP showed a significant correlation with CAI, MES, and UCEIS. Receiver operating characteristic curve analysis of biomarker data for predicting endoscopic remission showed that the accuracy of FIT was superior to that of PGE-MUM and CRP in the < 4-year group. CONCLUSIONS FIT is an accurate biomarker reflecting the endoscopic score until 4 years in patients with UC. However, owing to the increased number of false negatives, the usefulness of FIT may decline after 4 years. Hence, evaluation of UC in combination with other biomarkers is recommended.