Smoking and inflammatory bowel disease: a meta-analysis.

Objective: To assess whether there is a true effect of smoking on the 2 most prevalent forms of inflammatory bowel disease (IBD): Crohn disease (CD) and ulcerative colitis (UC).

Methods: For this meta-analysis, we searched multiple health care databases, including MEDLINE and EMBASE (January 1980 to January 2006), to examine the relationship between smoking and IBD. Keywords searched included smoking, Inflammatory bowel disease, Crohn's disease, and ulcerative colitis.