Faecal but not serum calprotectin levels look promising in predicting active disease in Behçet's syndrome patients with gastrointestinal involvement.

OBJECTIVES: The faecal calprotectin (FC) test is widely used as a non-invasive method for identifying intestinal inflammation. A recent study suggested FC may help to diagnose gastrointestinal involvement of Behçet's syndrome (GIBS). We aimed to determine whether FC helps to distinguish active from inactive intestinal involvement in GIBS.
METHODS: We tried to contact 70 GIBS patients registered in our tertiary multidisciplinary clinic. We prospectively collected faecal specimens and serum from 39 GIBS patients who gave informed consent assessing calprotectin and CRP levels followed by a colonoscopy. We included 47 Crohn's disease (CD) patients as controls. Active disease was defined as having ulcer/s on colonoscopy. We filled the Disease Activity Index for Intestinal Behçet's Disease (DAIBD) and Crohn's Disease Activity Index (CDAI). The cut-off for positive FC was defined as ≥150 μg/g.
RESULTS: Ulcers were detected in 12/39 GIBS patients. Sensitivity and specificity of the FC test for active disease was 91.7 (95%CI:61.5-99.8) and 74.1% (95%CI:53.7-88.9). Median FC and CRP levels and DAIBD scores were higher among patients with ulcers, whereas serum calprotectin and CDAI scores were not. A negative FC test was the only significant predictor of remission (OR:37.04, 95%CI:2.4-561.6; p=0.009) on multivariate analysis. Among CD patients, 16/25 active patients and 3/22 patients in endoscopic remission had a positive FC test (OR:11, 95%CI:11-49).
CONCLUSIONS: FC, but not serum calprotectin seems to be a useful non-invasive tool for assessing disease activity in GIBS. Whether the presence of oral ulcers can cause false positive results remains to be studied.