Smoking is Associated with an Increased Risk of Microscopic Colitis : Results From Two Large Prospective Cohort Studies of US Women

• Introduction: Long-term data on the influence of smoking on risk of microscopic colitis are limited. We therefore sought to examine and characterize the association between smoking and risk of incident microscopic colitis in two large prospective cohorts of women.Methods: We conducted a prospective study of 231,015 women enrolled in the Nurses' Health Study (NHS) and NHSII. Information regarding smoking, other lifestyle factors, and medications were collected biennially from 1976 to 2012 in NHS and 1989 to 2013 in NHSII. Incident cases of microscopic colitis were confirmed through physician medical record review. We used Cox proportional hazards modeling to examine the association between smoking and risk of microscopic colitis.Results: We documented 166 incident cases of microscopic colitis over 6,122,779 person-years of follow up. Compared to non-smokers, the multivariable-adjusted hazard ratio (HR) for microscopic colitis was 2.52 (95% CI 1.59 - 4.00) amongst current smokers and 1.54 (95% CI 1.09 - 2.17) amongst past smokers. The risk increased with higher pack-years of smoking (Ptrend = 0.001) and diminished following smoking cessation (Ptrend = 0.017). Current smoking appeared to be more strongly associated with risk of collagenous colitis (3.68; 95% CI 1.94 - 6.97) than lymphocytic colitis (HR 1.71; 95% CI 0.83 - 3.53).Conclusion: In two large prospective cohort studies, we observed an association between current smoking and risk of microscopic colitis. Risk of microscopic colitis appeared to increase with higher pack-years and diminish following smoking cessation. Future studies focused on characterizing the biologic mechanisms underlying these associations are warranted.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Gastroenterologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Gastroenterology and Hepatology (hsv//eng)

Nyckelord

Collagenous Colitis

Lymphocytic colitis

Microscopic Colitis

Nurses’ Health Study

Smoking

Tobacco

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