Generational increase of self-reported first attack of asthma in fifteen industrialized countries

The prevalence of asthma has increased worldwide. However, there is only lo cal evidence for changes in incidence. Data from the European Community Res piratory Heath Survey (ECRHS) can be analysed to reconstruct trends in inci dence from 1946-1991 in cohorts born between 1946-1971 in 35 areas correspo nding to 15 countries. The authors report the time trends in self-reported first occurrence of asthma and its geographical distribution. All centres completed the same cross-sectional study in 1991-92. A total of 17,613 individuals (63% of those randomly selected) were included. Recall of age of first asthma attack was recorded at an interview at one point in time in subjects aged 20-44 yrs. Relative risk of asthma by cohort was esti mated using survival methods with age as the time scale. Yearly incidence of asthma increased progressively by birth cohort. The rel ative risks were 1.12 (0.9-1.34), 1.39 (1.17-1.66), 2.01 (1.60-2.51), and 2 .33 (1.81-2.98) for the cohorts born in the years 1951-55, 1956-60, 1961-65 , and 1966-71, respectively, in comparison with the cohort born in the year s 1946-50. The increase occurred concurrently in most of the countries, in both males and females, and both in childhood and adulthood onset asthma. These results are consistent with a generational increase in asthma inciden ce during the previous decades (explained by both a period and/or a cohort effect), although some of the findings could be explained by generational i ncreases in asthma diagnosis.