Objective: The rise in the prevalence of asthma in the second half of the 20th century has not been evenly distributed according to recent surveys. We assessed changes in the prevalence of asthma after a period of 9 to 10 years in a cohort of young adults in the Spanish arm of the European Community Respiratory Health Survey (ECRHS).
Material and methods: The ECRHS-II is a multicenter cohort study taking place in 27 centers around Europe, with Spanish centers located in Albacete, Barcelona, Galdakao, Huelva, and Oviedo. The ECRHS questionnaire was administered to individuals who had participated in the first phase of the survey; spirometry and methacholine challenge tests were also performed according to the published protocol.
Results: Among new smokers, the prevalence of wheezing in the last 12 months increased from 10% to 33%, while the frequency of phlegm production rose from 8% to 22% (P< .05). In ex-smokers, the prevalences of wheezing and phlegm production decreased from 21% to 12% and from 15% to 8%, respectively (P< .05). Symptom prevalences remained similar for never smokers, although the frequency of diagnosed asthma rose from 4% to 7% (P< .05). After adjusting for smoking, age, sex, and center, we found no significant differences in the frequency of symptoms or asthma, even when the phrase bronchial hyperreactivity was included in the definition. However, the rate of reported asthma rose annually by 0.34% (95% confidence interval [CI], 0.20%-0.48%), while diagnosed asthma rose by 0.26% (95% CI, 0.13%-0.39%) and treated asthma by 0.16% (95% CI, 0.07%-0.25%).
Conclusions: Increased prevalence rates of asthma diagnosis and treatment have been detected, but the rates of reported symptoms have remained similar, consistent with the assumption that more persons are being classified as asthmatics.