title: Diarrhoea and smoking: an analysis of decades of observational data from Bangladesh.
abstract: BACKGROUND
  Although cigarette smoking affects all biological systems of the human body including the gastrointestinal tract, there is a lack of evidence regarding its effect on the severity of diarrhoeal disease and whether a dose-response relationship exists. We therefore tested for the presence of specific causative pathogens for infectious diarrhoea, assessed the independent effect of smoking on its severity and tested whether any dose-response relationship existed while controlling for subjects' age, sociodemographic characteristics and presence of causative pathogens in an urban setting in Bangladesh.
  
  
  METHODS
  A total of 20,757 patients aged 15 years and above with diarrhoea were enrolled into the Diarrhoeal Disease Surveillance System, managed by the International Centre for Diarrhoeal Disease Research, Bangladesh, from 1993 to 2012. We collected data on individuals' current daily consumption of cigarettes and bidis (traditional hand-rolled cigarettes) and conducted an ordered logistic regression to determine the effect of smoking on diarrhoeal disease severity and whether a dose-response relationship exists.
  
  
  RESULTS
  We identified 19 % of patients with diarrhoea as smokers, of whom 52 % smoked 1-9 cigarettes per day. While 97 % of smokers were male, 41 % were aged 15-30 years of age. Smokers were found to have a significantly lower severity of diarrhoeal disease (OR: 0.92, 95 % CI: 0.85-0.99, p = 0.025) after adjusting for age, wealth quintile, illiteracy and the presence of specific causative pathogens (Vibrio cholerae and Shigella). We observed no dose-response relationship between the number of cigarettes smoked per day and disease severity when adjusting for the same covariates. Smokers were more frequently infected with Shigella (7 vs. 6 %, p < 0.001) and less often with Vibrio cholerae (22 vs. 26 %, p < 0.001) than their non-smoking counterparts.
  
  
  CONCLUSIONS
  The aetiology and severity of diarrhoeal disease differed between smokers and non-smokers in our sample. However, we found no dose-response relationship between disease severity and the number of cigarettes smoked per day.
authors.affiliation: Centre for Nutrition and Food Security (CNFS), International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. sumon@icddrb.org.|School of Public Health, The University of Queensland, Brisbane, Australia. sumon@icddrb.org.
authors.forename: Sumon Kumar
authors.initials: SK
authors.lastname: Das
authors.affiliation: Centre for Nutrition and Food Security (CNFS), International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. chisti@icddrb.org.
authors.forename: Mohammod Jobayer
authors.initials: MJ
authors.lastname: Chisti
authors.affiliation: Centre for Nutrition and Food Security (CNFS), International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. a.ahmed@uq.net.au.|School of Public Health, The University of Queensland, Brisbane, Australia. a.ahmed@uq.net.au.
authors.forename: A M Shamsir
authors.initials: AM
authors.lastname: Ahmed
authors.affiliation: Centre for Nutrition and Food Security (CNFS), International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. mamalek@icddrb.org.
authors.forename: Mohammad Abdul
authors.initials: MA
authors.lastname: Malek
authors.affiliation: Centre for Nutrition and Food Security (CNFS), International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. shahnawz@icddrb.org.
authors.forename: Shahnawaz
authors.initials: S
authors.lastname: Ahmed
authors.affiliation: Centre for Nutrition and Food Security (CNFS), International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. shahunja@icddrb.org.
authors.forename: K M
authors.initials: KM
authors.lastname: Shahunja
authors.affiliation: Department of Clinical Trial and Clinical Epidemiology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan. jhum01712@yahoo.com.
authors.forename: Farzana
authors.initials: F
authors.lastname: Ferdous
authors.affiliation: Centre for Nutrition and Food Security (CNFS), International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. fahmidaf@icddrb.org.
authors.forename: Fahmida Dil
authors.initials: FD
authors.lastname: Farzana
authors.affiliation: Centre for Nutrition and Food Security (CNFS), International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. jui.das@icddrb.org.
authors.forename: Jui
authors.initials: J
authors.lastname: Das
authors.affiliation: Centre for Nutrition and Food Security (CNFS), International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. draminur@icddrb.org.
authors.forename: Aminur
authors.initials: A
authors.lastname: Rahman
authors.affiliation: School of Public Health, The University of Queensland, Brisbane, Australia. mamun@sph.qu.edu.au.
authors.forename: Abdullah
authors.initials: A
authors.lastname: Al Mamun
authors.affiliation: Centre for Nutrition and Food Security (CNFS), International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. gfaruque@icddrb.org.
authors.forename: Abu Syed Golam
authors.initials: AS
authors.lastname: Faruque
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001459:Bangladesh / Q000453:epidemiology; D015897:Comorbidity; D003967:Diarrhea / Q000453:epidemiology*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D012720:Severity of Illness Index; D012907:Smoking / Q000453:epidemiology*; D012959:Socioeconomic Factors; D014029:Tobacco Use Disorder / Q000453:epidemiology*; D014505:Urban Population / Q000706:statistics & numerical data; D055815:Young Adult