To explore the differences of fecal calprotectin (FC), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) between colon and small intestinal Crohn′s disease, and their predictive values for disease activity and mucosal healing in patients with small intestinal Crohn′s disease.

From January 2017 to January 2023, 64 patients with Crohn′s disease who underwent capsule endoscopy in the First Affiliated Hospital of Zhejiang Chinese Medical University were enrolled, among them 28 patients had only small intestinal lesions (small intestine group) and 36 patients had lesions involving both small intestine and colon or only colon involvement (ileocolon group). The FC, CRP, and ESR levels of the two groups were detected and compared 15 days before capsule endoscopy examination. Wilcoxon rank-sum test was used for statistical analysis. Receiver operating characteristic curve analysis was used to evaluate the predictive value of FC, CRP, and ESR for disease activity and mucosal healing in patients with small intestinal Crohn′s disease.

The FC, CRP, and ESR levels of the small intestine group during the active phase of the disease were 1 689.00 μg/g (727.75 μg/g, 1 800.00 μg/g), 5.67 mg/L (1.00 mg/L, 17.01 mg/L), and 4.50 mm/1 h (2.00 mm/1 h, 11.00 mm/1 h), respectively; while FC, CRP, and ESR levels during the mucosal healing phase were 112.00 μg/g (46.50 μg/g, 130.50 μg/g), 1.00 mg/L (1.00 mg/L, 1.62 mg/L), and 2.00 mm/1 h (2.00 mm/1 h, 5.50 mm/1 h), respectively. The FC, CRP, and ESR levels of the ileocolon group during the active phase of the disease were 1 800.00 μg/g (895.50 μg/g, 1 800.00 μg/g), 4.94 mg/L (3.10 mg/L, 14.80 mg/L), and 10.00 mm/1 h (2.00 mm/1 h, 27.75 mm/1 h), respectively, while FC, CRP, and ESR levels during the mucosal healing phase were 66.00 μg/g (32.50 μg/g, 97.50 μg/g), 1.00 mg/L (1.00 mg/L, 1.55 mg/L), and 2.00 mm/1 h (2.00 mm/1 h, 4.50 mm/1 h), respectively. There were no statistically significant differences in FC, CRP, and ESR between the small intestine group and the ileocolon group during the active phase of the disease and mucosal healing phase (all P> 0.05). In the small intestine group, the levels of FC and CRP of patients during the active phase of the disease were 1 173.00 μg/g (312.00 μg/g, 1 800.00 μg/g) and 2.10 mg/1 L (1.00 mg/L, 16.00 mg/L), which were both higher than those of patients during the mucosal healing phase (112.00 μg/g (46.50 μg/g, 130.50 μg/g) and 1.00 mg/L (1.00 mg/L, 1.62 mg/L)), and the differences were statistically significant (Z=-4.35 and-2.67, P<0.001 and =0.008). In the small intestine group, the level of ESR of patients during the active phase of the disease was 4.00 mm/1 h (2.00 mm/1 h, 16.00 mm/1 h), and there was no significant difference compared with that of patients during the mucosal healing phase (2.00 mm/1 h (2.00 mm/1 h, 5.50 mm/1 h)) (P>0.05). When the cut-off level of FC was 188.50 μg/g, the sensitivity, specificity, and area under the curve for predicting disease activity in patients with small intestinal Crohn′s disease was 93.3%, 100.0%, and 0.964, respectively. When the cut-off value of CRP was 3.12 mg/L, the sensitivity, specificity, and area under the curve for predicting disease activity in patients with small intestinal Crohn′s disease was 46.7%, 92.3%, and 0.744, respectively. When the cut-off level of ESR was 10.00 mm/1 h, the sensitivity, specificity, and area under the curve for predicting disease activity in patients with small intestinal Crohn′s disease was 33.3%, 100.0%, and 0.654, respectively. There were no statistically significant differences in the area under the curve between the combinations of FC and CRP, FC and ESR, FC, CRP and ESR, and FC alone for predicting disease activity in patients with small intestinal Crohn′s disease (0.964, 0.959, and 0.959 vs. 0.964, all P> 0.05). There was a statistically significant difference in the area under the curve between the combination of CRP and ESR and FC alone in predicting disease activity in patients with small intestinal Crohn′s disease (0.708 vs. 0.964, Z=-2.57, P=0.010).

There are no statistically significant differences in FC, CRP, and ESR between colon and small intestinal Crohn′s disease. FC has a high predictive value for disease activity and mucosal healing in patients with small intestinal Crohn′s disease and has certain clinical application value.

Fecal calprotectin; C-reactive protein; Erythrocyte sedimentation rate; Crohn disease; Mucosal healing