title: Family history, comorbidity, smoking and other risk factors in microscopic colitis: a case-control study.
abstract: OBJECTIVE
  Data on heredity, risk factors and comorbidity in microscopic colitis, encompassing collagenous colitis (CC) and lymphocytic colitis (LC), are limited.
  
  
  OBJECTIVE
  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.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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: aSchool of Medical Sciences, Örebro University, Örebro bThe Clinical Epidemiology Unit, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden cDepartment of Epidemiology and Public Health, University College London, London, UK.
authors.forename: Anna
authors.initials: A
authors.lastname: Wickbom
authors.forename: Nils
authors.initials: N
authors.lastname: Nyhlin
authors.forename: Scott M
authors.initials: SM
authors.lastname: Montgomery
authors.forename: Johan
authors.initials: J
authors.lastname: Bohr
authors.forename: Curt
authors.initials: C
authors.lastname: Tysk
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001327:Autoimmune Diseases / Q000453:epidemiology; D016022:Case-Control Studies; D046729:Colitis, Collagenous / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000235:genetics; D046730:Colitis, Lymphocytic / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000235:genetics; D046728:Colitis, Microscopic / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics; D003093:Colitis, Ulcerative / Q000453:epidemiology; D015897:Comorbidity; D004522:Educational Status; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D017533:Marital Status; D008875:Middle Aged; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology; D013548:Sweden / Q000453:epidemiology