Epidemiology of Persistent Cough.

Persistent cough is a widespread symptom in the American population. It initially aroused the interest of the present investigators because of its apparent association with bronchiogenic carcinoma. This led to the study of environmental factors that might contribute to persistent cough. The present report concerns the results of investigations carried out among non-lung cancer patients on the east and west coasts of the United States. In a separate communication, data from a study of persistent cough in lung cancer patients will be presented. Several American and British studies have been concerned with the relation of environmental factors to persistent cough. These have been reviewed by the Surgeon General's advisory committee in its report on health and smoking ( 1) . On the whole, these studies have indicated a close relationship between smoking, particularly cigarette smoking, and persistent, productive cough. Information on this relationship, abstracted from the studies, is summarized in table 1. In general, the reports of these studies have not presented detailed information on smoking habits beyond the type of tobacco used and the amount smoked. In only a few of the studies have occupational factors been considered. However, when they have been considered ( 6, 15), no close association has been found between occupational background and persistent cough. Some of the other factors that have been thought to be related to cough are air pollution and climate (17, 18). British workers consider these factors to be of particular importance in the pathogenesis of chronic bronchitis which has a high prevalence rate among th~ population. Fletcher has stressed not only the