Abstract

Background and aims: C-reactive protein (CRP) levels are often used in following up patients with inflammatory bowel disease (IBD). The aims of this study were to establish the relationship of CRP levels to disease extent in patients with ulcerative colitis (UC) and to phenotype in patients with Crohn’s disease (CD), and to investigate the predictive value of CRP levels for disease outcome.

Methods: CRP was measured at diagnosis and after one and five years in patients diagnosed with IBD in south-eastern Norway. After five years, 454 UC and 200 CD patients were alive and provided sufficient data for analysis.

Results: CD patients had a stronger CRP response than UC patients. In UC patients, CRP levels at diagnosis increased with increasing extent of disease. No differences in CRP levels at diagnosis were found between subgroups of CD patients as defined according to the Vienna classification. In UC patients with extensive colitis, CRP levels above 23 mg/L at diagnosis predicted increased risk of surgery (OR 4.8 95 % CI 1.5 - 15.1 p = 0.02) and CRP levels in UC patients above 10 mg/L after one year predicted increased risk of surgery during the subsequent four years (OR 3.0 95 % CI 1.1 - 7.8, p = 0.02). A significant association between CRP levels at diagnosis and risk of surgery was found in CD patients with terminal ileitis (L1), and the risk increased when CRP levels were above 53 mg/L in this subgroup (OR 6.0 95 % CI 1.1 - 31.9, p = 0.03).

Conclusions: CRP levels at diagnosis were related to the extent of disease in UC patients. Phenotype had no influence on CRP levels in CD patients. CRP is a predictor of surgery in subgroups of UC and CD patients.