Correlation of C-Reactive Protein with Clinical and Endoscopic Activity in Patients with Ulcerative Colitis

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.

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.

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).

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