42 The Epidemiology of Asthma

Publication date: 2019
Source:Kendig's Disorders of the Respiratory Tract in Children
Author(s): Alexander John Henderson
Epidemiology is the study of populations to discover modifiable factors that contribute to disease occurrence and natural history with a view to reducing disease burden through prevention. Asthma is a complex, polygenic disease with heterogeneous manifestations making it difficult to define precisely in population studies. Despite this, global efforts to harmonize outcome definitions have led to detailed understanding of the temporal and spatial variations of asthma prevalence in children. Asthma prevalence notably increased in high-income countries during the final three decades of the 20th century, but the cause for this has never been fully established.Early life has been implicated as a critical period for the development of asthma. Many environmental influences have been considered as potential risk factors for asthma, but few have been associated with more than modest increases in risk. One barrier to identifying causal risk factors is the clustering of environmental factors with consequent confounding of relationships between environment and disease. Thus even strong and reproducible associations can seldom be regarded as causal without experimental evidence, which is generally lacking.Despite these difficulties, new approaches to asthma classification, meticulous observations in birth cohorts, technological advances that enable assignment or genetic risk and identification of biomarkers for disease pathways, and analytical advances have contributed to real advances in understanding asthma pathogenesis. The interaction of allergic sensitization with respiratory viral infections offers a promising target for the development of preventative interventions.



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