The effect of smoking and occupation on changes in respiratory symptoms in middle-aged Danish men

A group of 1404 middle-aged men from Aalborg who were examined in 1974 with interview and lung function tests were re-examined in 1985 using a postal questionnaire. Of the 1404 men, 1045 could be classified into well-defined occupational categories using information up to 1974. Of these men, 791 were alive at the time of the questionnaire survey. Questions on lung symptoms, occupation and smoking habits since the 1974 study were included in the follow-up survey; the response rate was 88%. Age and main occupation until 1974 were significantly related to the development of severe breathlessness from 1974 to 1985. After controlling for age, both cement workers and blue collar workers were considerably more likely to develop severe breathlessness than white collar workers: odds ratios (ORs) 2.51 (95% confidence interval 1.04-6.7) and 2.35 (1.02-5.42), respectively. Although weakened, these relationships remained after further controlling for forced expiratory volume in one second (FEV1) in 1974. Present smoking habit was an important determinant for the presence of cough, both in men with and without cough in 1974, yielding ORs of approximately 3 when comparing with lifetime nonsmokers. Cement workers tended to have cough in 1985 more frequently than white collar workers, OR = 2.09 (0.89-4.89) for men without cough in 1974 and OR = 2.60 (1.04-6.51) for men with cough in 1974.