Correlation of C-reactive protein with clinical and endoscopic activity in patients with ulcerative colitis

Abstract

Background and aims: Evaluating disease activity is important in ulcerative colitis. Laboratory markers should be a non-invasive alternative to endoscopy for patients. The objective of our study was to scrutinize the correlation between C-reactive protein (CRP) levels and clinical and endoscopic activity in ulcerative colitis patients.

Materials and methods: We conducted a prospective study between January 2007 and December 2009. In the study we chose consecutive patients of our department with ulcerative colitis. All patients received a standardized questionnaire, clinical examination, and colonoscopy. Based on clinical and endoscopic data, we calculated the disease activity index (DAI) and the Rachmilewitz score.

Results: One-hundred and one patients were included. At the time of inclusion, 67 patients had an active disease and 34 patients were in remission. The mean DAI was 6.9 (1-12). The mean Rachmilewitz score was 4.7 (0-12). The median CRP rate was 20.2 ± 24.5 mg/l (1-107 mg/l). An increased CRP was found in 46 patients (46%). An increased CRP level was observed in patients with active disease (P < 0.0001). The DAI was higher in patients with increased CRP (9.5 ± 1.6 vs. 4.7 ± 3.6; P < 0.0001). The Rachmilewitz score was also higher in patients with increased CRP (7.2 ± 2.3 vs. 2.7 ± 3.2; P < 0.0001). A statistically significant association was found between the CRP and the DAI (r = 0.51, P < 0.0001) and between the CRP and the Rachmilewitz score (r = 0.46, P < 0.0001). The optimum cut-off of CRP level that separates active or inactive disease was calculated to be 10 ml/l, with AUC estimated at 0.81 ± 0.04 (95%CI: 0.72-0.88), a sensitivity of 67.1 (95%CI: 54.6-78.1) and a specificity of 97% (95%CI: 84.6-99.5).

Conclusion: Levels of CRP are correlated to clinical and endoscopic activity in ulcerative colitis patients.