Prevalence and risk factors for chronic bronchitis in Pelotas, RS, Brazil: A populationbased study

Background - Chronic bronchitis causes high morbidity and mortality throughout the world. It is basically a preventable disease. However, few population based studies ofchronic bronchitis have been carried out in less developed countries. Methods - A population based cross sectional survey was conducted to determine the prevalence of chronic bronchitis and associated risk factors in an urban area (Pelotas) of southern Brazil. 1053 subjects aged 40 years and over (90.3% of eligible subjects) were interviewed using the ATSDLD- 78 questionnaire. Results- Ofthe subjects interviewed 12 7% were classified as having chronic bronchitis. In univariate analyses a significant increase in the relative odds of chronic bronchitis was seen in men (OR= 2 17, 95% CI 1 50 to 3.13), low family income (OR= 2-60, 95% CI 1 47 to 4 47 for lowest quartile), low schooling (OR= 4.65, 95% CI 2-36 to 9-18 for those with no schooling), smoking habits (OR= 6.92, 95% CI 4-22 to 11-36 for smokers of 20 or more cigarettes per day), high occupational exposure to dust (OR=2.48, 95% CI 1-56 to 3-94), inadequate housing (OR= 2 099 95% CI 1 22 to 3-58), high level of indoor air pollution (OR=1-86, 95% CI 1-16 to 2.99), and reported childhood respiratory illnesses (OR=2.08, 95% CI 125 to 3.49). Multiple logistic regression resulted in the identification ofthe following independent risk factors: family income (OR= 1 999 95% CI 104 to 3 81 for subjects in the lowest quartile compared with those in the highest quartile), schooling (OR=5 60, 95% CI 2-52 to 12'45 for subjects with no schooling compared with those with nine or more years), smoking (OR= 8.10, 95% CI 4.46 to 14 71 for smokers of 20 or more cigarettes per day compared with non-smokers), and history of major respiratory illnesses in childhood (OR=2.169 95% CI 120 to 3.85). Conclusions - Low family income, poor schooling, smoking, and childhood respiratory illnesses were significantly associated with chronic bronchitis.