Simultaneous measurements of faecal calprotectin and the faecal immunochemical test in quiescent ulcerative colitis patients can stratify risk of relapse

Background: Both faecal calprotectin [Fcal] and the faecal immunochemical test [FIT] are useful to predict clinical relapse of ulcerative colitis [UC]. However, the difference between Fcal and FIT in ability to predict relapse has scarcely been reported. Whether the combined use of these two faecal markers increases the predictability is also unknown. Methods: UC patients in clinical remission who underwent colonoscopy were enrolled prospectively, and the Fcal and FIT values were examined at enrolment. Their clinical course was observed for 2 years or until relapse. The correlation between the incidence of relapse and the values of the two markers was examined. Results: A total of 113 patients were enrolled, and 48 [42%] relapsed. Fcal = 75 μg/g and FIT = 110 ng/mL were defined as Fcal-positive and FIT-positive, respectively, according to the receiver operating characteristic curves. Both Fcal-positive and FIT-positive statuses were independent predictive factors of clinical relapse (hazard ratio [HR] 2.29; 95% confidence interval [CI], 1.23-4.49; p = 0.0086, and HR 2.91; 95% CI, 1.49-5.50; p = 0.0022, respectively). Categorisation of patients into three groups according to the faecal marker status [FIT-positive, FIT-negative and Fcal-positive, and both negative] can efficiently stratify the risk of relapse with graded increases in risk [FIT-negative and Fcal-positive: HR 2.05; 95% CI, 1.02-4.43; p = 0.0045, and FIT-positive: HR 5.43; 95% CI, 2.57- 11.76; p < 0.0001, compared with both negative]. Conclusions: Fcal vs FIT showed distinct properties regarding the prediction of relapse in UC. A risk assessment using both faecal markers could increase the predictability for relapse.