Abstract Background Fecal calprotectin (FC) has been considered a potential surrogate biomarker for evaluating gastrointestinal inflammation in Crohn’s disease (CD). We aim to investigate the predictive value of FC for disease activity in CD patients. Methods A retrospective study was conducted on CD patients at our center from January 1, 2016 to December 31, 2024. Data collected included FC test results, as well as other concurrent laboratory, endoscopic and imaging examinations. The Crohn’s Disease Activity Index (CDAI) and the Simple Endoscopic Score for Crohn’s Disease (SES-CD) were used respectively to assess clinical and endoscopic disease activity. Results A total of 217 patients were enrolled (158 underwent multiple FC tests), providing 479 cases of complete data for FC levels and CDAI scores, and 103 cases for FC levels and SES-CD scores. FC levels were significantly higher in patients with colonic involvement than in those without (P 0.05). There was no significant difference in FC levels between patients with and without perianal/penetrating disease (P = 0.138), nor between those with and without stricturing disease (P = 0.452). FC levels were correlated with both CDAI and SES-CD scores (both P 0.001) during biologic therapies. The area under the curve (AUC) for FC in predicting clinical activity was 0.710 (P = 0.001, cutoff: 342.1 μg/g, sensitivity: 0.648, specificity: 0.700). The AUC for predicting endoscopic activity was 0.772 (P 0.001, cutoff: 103.67 μg/g, sensitivity: 0.727, specificity: 0.867). Conclusion FC levels in CD patients vary by disease location, with higher levels observed in those with colonic involvement, and are correlated with both clinical and endoscopic activity, indicating a certain predictive value for assessing disease activity in CD. Conflict of interest: Ms. Yuan, Bingqing: No conflict of interest Chen, Yanjun: No conflict of interest Liu, Ji: No conflict of interest Xie, Yitong: No conflict of interest Feng, Ziqin: None Dong, Rufang: No conflict of interest Chen, Weichang: No conflict of interest
Yuan et al. (2026) studied this question.