The meaning of low-grade inflammation in clinically quiescent inflammatory bowel disease

Low-grade inflammation can persist in many patients with inflammatory bowel disease (IBD) who have otherwise obtained clinical remission. This review will summarize the prognostic implications of this finding for patients.

At least 40% of patients with IBD in clinical remission have ongoing histological evidence of inflammation, despite continued use of maintenance therapy. Follow-up endoscopy and biopsy is the current gold standard for identifying these patients. Recent studies have suggested that an elevated C-reactive protein is associated with underlying histological abnormalities in this setting. Patients with histological inflammation at baseline are at increased risk of clinical relapse, hospitalization, surgery, and colon cancer in observational longitudinal studies. Even when endoscopic healing has been achieved, the presence of underlying architectural changes on biopsies can identify patients at a higher risk of complications. Prospective studies to determine if 'histological healing' provides additional outcome benefits beyond endoscopic or clinical remission alone have not been performed to date, but warrant inclusion in future trials.

Chronic low-grade inflammation is common in patients with IBD in clinical remission. Clinicians should actively try to identify these patients and consider a lower threshold for intervention to reduce their higher risk of adverse outcomes over time.