title: Inverse association between coffee consumption and risk of cholecystectomy in women but not in men.
abstract: OBJECTIVE
  There is conflicting epidemiologic evidence on whether coffee consumption reduces the risk of gallstone disease. We examined the association between coffee consumption and risk of cholecystectomy (as a proxy for symptomatic gallstone disease) in a prospective cohort study.
  
  
  METHODS
  We collected data from 30,989 women (born 1914-1948) and 40,936 men (born 1918-1952) from the Swedish Mammography Cohort and the Cohort of Swedish Men. Baseline information on coffee consumption was collected by using a food-frequency questionnaire; subjects were followed up for procedures of cholecystectomy from 1998 through 2011 by linkage to the Swedish Patient Register. Hazard ratios (HRs) were estimated by using Cox proportional hazard models.
  
  
  RESULTS
  During a total follow-up period of 905,933 person-years, we identified 1057 women and 962 men who had undergone a cholecystectomy. After adjustment for potential confounders, the HR of cholecystectomy was 0.58 (95% confidence interval [CI], 0.44-0.78) for women who drank ≥6 cups of coffee/day compared with women who drank <2 cups/day. In contrast, there was no association in men (HR, 0.96; 95% CI, 0.75-1.24). Because of this sex difference, we examined and found evidence of effect modification by menopausal status and use of hormone replacement therapy (HRT) (Pinteraction = .026). An inverse association was observed only in women who were premenopausal (HR, 0.17; 95% CI, 0.05-0.55) or used HRT (HR, 0.44; 95% CI, 0.28-0.70).
  
  
  CONCLUSIONS
  We observed an inverse association between coffee consumption and risk of cholecystectomy in women who were premenopausal or used HRT but not in other women or in men.
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden. Electronic address: caroline.nordenvall@ki.se.
authors.forename: Caroline
authors.initials: C
authors.lastname: Nordenvall
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Viktor
authors.initials: V
authors.lastname: Oskarsson
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Alicja
authors.initials: A
authors.lastname: Wolk
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002763:Cholecystectomy / Q000706:statistics & numerical data*; D003069:Coffee; D005247:Feeding Behavior; D005260:Female; D005500:Follow-Up Studies; D042882:Gallstones / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D018570:Risk Assessment; D011795:Surveys and Questionnaires
chemical_list: D003069:Coffee
keywords: Diet; Gallbladder; Surgery; Sweden