Majority of patients with inflammatory bowel disease in clinical remission have mucosal inflammation.

BACKGROUND: Management of inflammatory bowel disease (IBD) is increasingly focused on mucosal remission. We assessed the prevalence of mucosal inflammation during clinical remission, the clinical consequences, and the impact on disease course.
METHODS: IBD patients from two referral centers who underwent a surveillance colonoscopy while clinically in remission between January 2001 and December 2003 were included. Follow-up ended May 1, 2009. Clinical data were collected from patient charts. Statistical analysis was performed using independent t-tests and nonparametric tests.
RESULTS: In total, 152 IBD patients were included (98 [65%] ulcerative colitis, 46 [30%] Crohn's disease; 85 [56%] males). Median follow-up was 6.8 years (interquartile range [IQR] 6-8). Forty-seven (31%) patients had no signs of inflammation during endoscopy (group A). Of the remaining 105 (68%) patients, 51 (49%) had both endoscopic and histological inflammation (group B), 51 (49%) histological inflammation only (group C), two (2%) endoscopic lesions only (group D). Two years later, 29% of all patients had endoscopic inflammation and another 27% had only microscopic inflammation. In 39% the inflammation had resolved spontaneously. Inflammation was more often found in group B+C (n = 62/102; 61%) than in group A (n = 17/47; 36%; P = 0.21). Inflammation was not associated with more frequent clinical relapses nor with stricture formation, nor with the need for surgery.
CONCLUSIONS: A large proportion of IBD patients have mucosal inflammation without clinical symptoms. Although one-third recover spontaneously, mucosal inflammation in patients who are clinically in remission is associated with more severe mucosal disease activity, but not with more complications or symptomatic flares during follow-up.