Health care education, delivery, and quality
Asthma cases attributable to atopy: Results from the Third National Health and Nutrition Examination Survey

https://doi.org/10.1016/j.jaci.2007.07.056Get rights and content

Background

The percentage of asthma cases attributable to atopy is the subject of debate.

Objectives

The objectives were to estimate the percentage of asthma cases in the US population attributable to atopy and to examine associations between allergen-specific skin tests and asthma.

Methods

Data were obtained from the Third National Health and Nutrition Examination Survey, in which subjects age 6 to 59 years were skin tested with 10 allergens. Atopy was defined as at least 1 positive allergen-specific test. Doctor-diagnosed current asthma was assessed by questionnaire.

Results

In the United States, 56.3% of the asthma cases were attributable to atopy, and that percentage was greater among males than females, among persons in the highest education category than in lower education categories, and among persons living in highly populated metropolitan areas than in all other areas. Each allergen-specific test was strongly associated with asthma before adjustment (odds ratios varied from 2.1 to 4.5); however, after adjustment by all the allergens, only tests to cat, Alternaria, white oak, and perennial rye were independently associated with asthma. Perennial rye was inversely associated with asthma. Of the 10 allergens, a positive response to cat accounted for the highest percentage of asthma cases (29.3%).

Conclusion

About half of the current asthma cases in the US population represented by the Third National Health and Nutrition Examination Survey were attributable to atopy. Some allergen-specific skin tests were not independently associated with asthma.

Clinical implications

If atopy could be prevented or reversed, or its effect on asthma blocked, then a large percentage of asthma cases in the US population could be prevented.

Section snippets

Data

Data were obtained from NHANES III, a complex survey designed to represent the civilian noninstitutionalized population of the United States. Questionnaires were administered to and medical examinations and laboratory tests conducted on 31,311 individuals age 2 months to 90 years. A subsample of 12,106 subjects consisting of all subjects age 6 to 19 years and a random half-sample of subjects age 20 to 59 years were selected for allergy skin testing.

Allergy skin testing and atopy

A panel of 10 allergens and 2 controls

Prevalence of asthma

The prevalence of asthma in the US population age 6 to 59 years was 5.2%. Of the subject characteristics evaluated, the prevalence of asthma differed significantly by race-ethnicity (P < .01) and body mass index (P = .03) (Table I). For race-ethnicity, asthma was most prevalent among non-Hispanic blacks, and for body mass index (BMI), asthma was most prevalent among persons categorized as obese. As categorized, there was no statistical difference by age (P = .06); however, the prevalence of

Discussion

In the US population age 6 to 59 years, 56.3% of current asthma cases were attributable to atopy, as measured by a positive skin test response to any of 10 allergens. The PAR was significantly greater among males than females, among persons in the highest education category than in lower education categories, and among persons living in highly populated metropolitan areas than in all other areas.

The PAR estimate for the US population is higher than the PAR reported in several studies. In the

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    Supported by the Intramural Research Programs of the National Institute of Environmental Health Sciences and the National Institute of Allergy and Infectious Diseases, the National Institutes of Health.

    Disclosure of potential conflict of interest: B. Vaughn is employed by Rho, Inc. The rest of the authors have declared that they have no conflict of interest.

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