Correlations of C-reactive protein levels and erythrocyte sedimentation rates with endoscopic activity indices in patients with ulcerative colitis

Background: Accurate assessment of endoscopic severity is essential to the early detection of relapses and treatment of patients with ulcerative colitis (UC). However, the relationships between non-invasive biomarkers and invasive endoscopic severity indices remain poorly understood. Methods: A total of 722 endoscopies in 552 patients were evaluated in this study. Endoscopic activity was assessed using five widely used endoscopic scoring systems: the Powell-Tuck assessment, Mayo Endoscopic Score, modified Baron Score, Rachmilewitz Endoscopic Activity Index, and Hanauer's Sigmoidoscopic Index. These five indices were compared with two non-invasive biomarkers, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels. Results: The Pearson's correlation coefficients of CRP and ESR with endoscopic indices were r = 0.457 and 0.342 in the Powell-Tuck assessment, r = 0.503 and r = 0.402 in the Mayo Endoscopic Score, r = 0.507 and 0.408 in Hanauer's Sigmoidoscopic Index, r = 0.520 and 0.433 in the modified Baron Score, and r = 0.523 and 0.435 in the Rachmilewitz Endoscopic Activity Index. Sensitivity and specificity ranges for CRP and ESR were 50.5-53.3 % and 68.7-71.3 % and 85.1-87.2 % and 63.4-66.4 %, respectively, for the detection of endoscopic remission using the five endoscopic indices. Conclusions: CRP and ESR levels were modestly correlated with endoscopic activity indices in UC patients. However, the low sensitivities for detecting endoscopic remission suggest that CRP or ESR alone is not sufficient to reflect endoscopic severity accurately.