What are the risk factors for asthma?

Updated: Oct 07, 2019
  • Author: John J Oppenheimer, MD; Chief Editor: Michael A Kaliner, MD  more...
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Risk factors for asthma include a family history of allergic disease, the presence of allergen-specific immunoglobulin E (IgE), viral respiratory illnesses, exposure to aeroallergens, cigarette smoke, obesity, and lower socioeconomic status.

A study by Zhang et al suggests that those children who are genetically predisposed to asthma may be at an even higher risk if they are overweight beyond infancy. [6]

Data from the Prevention of Allergy: Risk Factors for Sensitization in Children Related to Farming and Anthroposophic Lifestyle (PARSIFAL) Study and the Multidisciplinary Study to Identify the Genetic and Environmental Causes of Asthma in the European Community Advanced (GABRIELA) reinforce the concept of the hygiene hypothesis. [7] Using a cross-sectional design, the authors compared children living on farms to those in a reference group with respect to the prevalence of asthma and to the diversity of microbial exposure. The studies found that children who lived on farms had a lower prevalence of asthma and atopy and were exposed to a greater variety of environmental microorganisms than children in the reference group. The diversity of microbial exposure was inversely related to the risk of asthma (odds ratio for PARSIFAL, 0.62; 95% confidence interval [CI], 0.44-0.89; odds ratio for GABRIELA, 0.86; 95% CI, 0.75-0.99).

A more recent study looked at asthma risk and innate immunity in Amish and Hutterite children who live on traditional and industrialized farms, respectively. The prevalence of asthma and allergic sensitization was 4 and 6 times lower in the Amish population, with higher median endotoxin levels in house dust. There were also significant differences in microbial composition in dust samples and in innate immune cells between the two groups of children. The study suggested a protective effect of an Amish environment against the development of asthma. [8]   

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