Background

Microscopic colitis (MC) induces gastrointestinal symptoms, which are partly overlapping with irritable bowel syndrome (IBS), predominately in middle-aged and elderly women. The etiology is unknown, but association with smoking has been found. The aim of this study was to examine whether the increased risk for smokers to develop MC is a true association, or rather the result of confounding factors. Therefore, patients suffering from MC and population-based controls from the same geographic area were studied regarding smoking- and alcohol habits, and other simultaneous, lifestyle factors, concerning the clinical expression of the disease.

Methods

Women at the age of 73 years or younger, who had been treated for biopsy-verified MC at any of the Departments of Gastroenterology in Skåne, between 2002 and 2010, were invited to the study (240 patients). Women (737) from the population-based prospective cohort study, Malmö Diet and Cancer Study (MDCS), served as controls. A self-administered questionnaire about lifestyle factors, gastrointestinal symptoms, medical conditions and medication at the time for the study was sent by post.

Results

Altogether, 131 women with MC could be included after age-matching with controls (median age 56 years) and exclusion of secondary MC. Patients were divided into persistent MC (MC1) and transient MC (MC2). Past smoking was associated with increased risk to develop MC2 (OR = 2.67, 95 CI = 1.15–6.23), whereas current smoking was associated with increased risk to develop MC1 (OR = 3.18, 95 CI = 1.57–6.42). Concomitant symptoms of IBS were associated with smoking (OR = 4.24, 95 CI = 1.92–9.32). Alcohol drinking had no association with MC or IBS.

Conclusions

The results suggest that past smoking is associated with transient MC, whereas current smoking is associated with persistent MC. Smoking is associated with MC patients with concomitant IBS-like symptoms.