Endoscopy within 7 days after detecting high calprotectin levels can be useful for therapeutic decision-making in ulcerative colitis

The aim of this study was to assess the appropriate time interval to identify the association between the fecal calprotectin (FC) test and endoscopic activity, and to evaluate whether the time interval affects the therapeutic plan adjustment in patients with ulcerative colitis (UC). This study included 103 patients who underwent FC tests and endoscopic examinations within the past three months. The FC test results classified cases into three groups as follows: moderate to severe (>200, >250, or >300 μg/g), mild (100–200, 100–250, or 100–300 μg/g), and inactive (<100 μg/g) activity. The Mayo endoscopic subscore was used to determine endoscopic activity. Therapeutic plan adjustment included the addition or increased dosage of anti-inflammatory drugs, steroids, immunomodulators, and biologics. Using the cutoff value for FC of 200 μg/g, the appropriate time interval for dividing the association and non-association between Mayo endoscopic subscore and FC was 7 days (sensitivity, 74.4%; specificity, 50.0%; area under the curve [AUC], 0.6032). When using FC 250 or 300 μg/g, the appropriate time interval was 5.5 days, with a sensitivity of 71.7% and specificity of 49.1 (AUC 0.5862) in FC 250 μg/g, a sensitivity of 69.6%, and a specificity of 47.4 (AUC 0.5549) for FC 300 μg/g. Therapeutic plans changed in 29.1% of patients. In patients with shorter intervals (≤7 days) between the FC test and endoscopy, significant therapeutic plan adjustments were observed in patients with UC (36.5% vs. 17.5%, P = .047). Although the need for endoscopy within 7 days after detecting high FC (≥ 200 μg/g) was not statistically supported, endoscopy within a shorter interval (≤7 days) in UC patients with high FC can help determine the therapeutic plan.