Smoking Status Influences Clinical Outcome in Collagenous Colitis

Andreas Münch, Curt Tysk, Johan Bohr, Ahmed Madisch, Ole K. Bonderup, Ralf Mohrbacher, Ralph Mueller, Roland Greinwald, Magnus Ström, Stephan Miehlke

The relationship between clinical and histological parameters in collagenous colitis (CC) is poorly understood. Smoking is a risk factor for CC, whereas its impact on clinical activity and outcome is not well-known. In a post-hoc analysis from pooled data of two randomized controlled trials we assessed the association between demographical (gender, age, smoking habits, family history of inflammatory bowel disease), clinical variables (duration of symptoms, mean number of stools/watery stools per day, abdominal pain, clinical remission) and histological data (thickness of the collagen band, inflammation of the lamina propria, total numbers of intraepithelial lymphocytes, degeneration). Moreover, we analyzed the predictive value of baseline parameters on clinical outcome in a logistic regression model. Pooled data from 202 patients with active CC were available thereof 36% current smokers, 29% former smokers and 35% non-smokers. Smoking status was associated with decreased ability to achieve clinical remission (current smokers vs non-smokers: OR 0.31, 95% CI: 0.10-0.98, p=0.045; former smokers vs non-smokers: OR 0.19, 95% CI: 0.05-0.73, p=0.016). Current smokers had an increased mean number of watery stools at baseline compared to non-smokers (p=0.051) and increased mean number of watery stools per se was associated with decreased likelihood to obtain clinical remission (OR 0.63, 95% CI: 0.47-0.86, p=0.003). Patient's characteristics or histology at baseline had no association with clinical parameters or any predictive value on clinical outcome. Smoking worsens clinical symptoms in CC and is associated with increased number of watery stools and decreased likelihood to achieve clinical remission. There is no significant association between histology and clinical data.