[Epidemiological study of chronic bronchitis in a population sample aged 60-85 years: contributions to the study of the natural history of chronic bronchitis (author's transl)].

An epidemiological study was undertaken by means of the MRC questionnaire on respiratory symptoms and of spirographic tests (VC and FEV 1.0) in a population of elderly people (374 men and 377 women 60-85 years old) examined periodically during the last 10 years. In a large number (39,2%) of smokers who had persistent cough the spirographic values were normal. (The reference values for VC and FEV 1.0 were obtained by means of regression equations developed from samples of subjects belonging to the same age-group who had no history or symptoms of respiratory disease).