Data on heredity, risk factors and comorbidity in microscopic colitis, encompassing collagenous colitis (CC) and lymphocytic colitis (LC), are limited.Aim
The aim was to carry out a case–control study of family history, childhood circumstances, educational level, marital status, smoking and comorbidity in microscopic colitis.Methods
A postal questionnaire was sent in 2008–2009 to microscopic colitis patients resident in Sweden and three population-based controls per patient, matched for age, sex and municipality.Results
Some 212 patients and 627 controls participated in the study. There was an association with a family history of microscopic colitis in both CC [odds ratio (OR): 10.3; 95% confidence interval (CI): 2.1–50.4, P=0.004] and LC (OR not estimated, P=0.008). Current smoking was associated with CC [OR: 4.7; 95% CI: 2.4–9.2, P<0.001) and LC (OR: 3.2; 95% CI: 1.6–6.7, P=0.002). The median age at diagnosis was around 10 years earlier in ever-smokers compared with never-smokers.Results
CC was associated with a history of ulcerative colitis (UC) (OR: 8.7, 95% CI: 2.2–33.7, P=0.002), thyroid disease (OR: 2.3; 95% CI: 1.1–4.5, P=0.02), coeliac disease (OR: 13.1; 95% CI: 2.7–62.7, P=0.001), rheumatic disease (OR 1.9; 95% CI: 1.0–3.5, P=0.042) and previous appendicectomy (OR: 2.2; 95% CI: 1.3–3.8, P=0.003), and LC with UC (OR: 6.8; 95% CI: 1.7–28.0, P=0.008), thyroid disease (OR: 2.4; 95% CI: 1.1–5.4, P=0.037) and coeliac disease (OR: 8.7; 95% CI: 2.8–26.7, P<0.001).Conclusion
Association with a family history of microscopic colitis indicates that familial factors may be important. The association with a history of UC should be studied further as it may present new insights into the pathogenesis of microscopic colitis and UC.