The epidemiology of cough.

Cough is a common symptom that affects a large proportion of the general population, but has been somewhat neglected in the epidemiological literature in the recent years. Various types of coughs are described based on life-long epidemiological surveys. Using published and unpublished data from three epidemiological studies (the European Community Respiratory Health survey, the French Epidemiological study on the Genetics and environment of asthma (EGEA) and the French E3N study), some specific aspects are discussed in detail. Phenotypic heterogeneity according to chronicity, or its productive nature, or its daytime or nocturnal characteristics are discussed. The association of cough with asthma and gender is described, together with its evolution over a 12-year period. The potential for genetic studies of cough is discussed.