Exposure to cold and draught, alcohol consumption, and the NS-phenotype are associated with chronic bronchitis: an epidemiological investigation of 3387 men aged 53-75 years: the Copenhagen Male Study

Objectives-This study was performed to estimate the strength of association between chronic bronchitis and lifetime exposure to occupational factors, current lifestyle, and the NS-phenotype in the MNS blood group among middle aged and elderly men. Methods-The study was carried out within the frameworks of the Copenhagen M ale Study. Of 3387 men 3331 men with a mean age of 63 (range 53-75) years c ould be classified by prevalence of chronic bronchitis. As well as the comp letion of a large questionnaire on health, lifestyle, and working condition s, all participants had a thorough examination, including measurements of h eight and weight and blood pressure and a venous blood sample was taken for the measurement of serum cotinine and MNS typing; 16.5% of the men had the NS-phenotype. Chronic bronchitis was defined as cough and phlegm lasting 3 months or more for at least 2 years; 14.6% had chronic bronchitis. Results-Smoking and smoke inhalation were the factors most strongly associa ted with prevalence of chronic bronchitis. There were three major new findi ngs: (a) long term (>5 years) occupational exposure to cold and draught was associated with a significantly increased prevalence of chronic bronchitis ; compared with others, and adjusted for confounders, the odds ratio (OR) w ith 95% confidence interval (95% CI) was 1.4 (1.1 to 1.7), p=0.004; (b) a s ignificant J shaped association existed between alcohol use and bronchitis, p<0.001, with the lowest prevalence found among moderate users; (c) a sign ificant gene by environment association existed between smoking and the NS- phenotype in the MNS blood group; only among smokers was the NS-phenotype a ssociated with a significantly decreased risk of chronic bronchitis, OR 0.6 7 (0.47-0.97), p=0.02. Other well known associations between dust, fumes, a nd even exposure to solvents and bronchitis were confirmed. Conclusion-The results emphasise the multifactorial nature of chronic bronc hitis, and show some hitherto unrecognised associations between cold and dr aught exposure, alcohol consumption, and the NS-phenotype and chronic bronc hitis.