Epidemiology of asthma across the ages.

In the past 3 decades, the overall prevalence of asthma appears to be plateauing, although large geographic and socioeconomic variation is evident. Overall, asthma prevalence slightly decreased in most age groups, except for school-aged children. Of note, asthma mortality steadily decreased, potentially highlighting improved asthma management strategies. Several epidemiologic studies indicate that a complex interplay between genetic, environmental, and immunologic factors predisposes individuals to asthma inception and persistence across different life stages. Established risk factors for preschool wheezing to asthma persistence comprise a combination of pre- and post-natal parameters including the maternal history of asthma, prematurity, caesarian section, early-life respiratory infections, exposure to air pollution or tobacco smoke, and allergic polysensitization. On the other hand, persistence into adulthood is mainly driven by disease severity, allergic multimorbidity, relevant comorbidities, severe respiratory infections, and tobacco smoke exposure. It is evident that asthma prevention strategies do not fit a "one size fits all" concept and key environmental interventions should be tailored to different regions of the world. Undoubtedly, the heterogeneity of asthma as a disease is at least partly reflected in the reported epidemiologic measures, and continuing, methodologically rigorous studies will allow us to unravel some of the observed discrepancies.