Older Adult Asthma Patients Often Also Have Allergies

Larry Hand

April 04, 2013

Contrary to popular opinion, older adults with asthma also have at least one allergy, according to an article published in the April issue of the Annals of Allergy, Asthma & Immunology.

Paula J. Busse, MD, from the Division of Clinical Immunology, Mount Sinai School of Medicine, New York City, and colleagues analyzed the records of 2573 people included in the National Health and Nutrition Examination Survey (NHANES) 2005-2006 to assess immunoglobulin E–mediated sensitization rates in adults with asthma. The investigators compared the prevalence of sensitization in 2 age groups of participants: adults aged 20 to 40 years and adults aged 55 years old or older.

More than 62% of all patients were non-Hispanic, and about 80% had at least a high school education.

Of the 1623 younger patients (51% women), the researchers identified 108 (6.7%) individuals who had physician-diagnosed cases of asthma. Among the 950 older patients (61.5% women), the investigators identified 43 (4.5%) individuals with asthma. In the younger group, 75.4% of the individuals with asthma had at least 1 allergen sensitization, as did 65.2% of the older adults with asthma. The difference between the 2 groups did not reach statistical significance.

The researchers calculated the adjusted odds ratio (OR) for immunoglobulin E–mediated sensitization, using logistic regression and adjusting for sex, race/ethnicity, and educational level. Older adults with asthma had nearly a 3-fold increased risk for allergy compared with participants without asthma (95% confidence interval [CI], 1.7 - 4.9]; the risk was even greater for younger individuals with asthma (OR, 3.5 [95% CI, 2.3 - 5.2]).

Older patients with asthma most often were sensitized to dust mite (Dermatophagoides pteronyssinus, 36.3%) and rye grass (33.1%), with 50.2% being sensitized to at least 1 indoor allergen and 39.3% to at least 1 outdoor allergen. Younger patients with asthma were most often sensitized to dog (49.5%) and dust mite (D pteronyssinus [44.8%] and D farinae [41.4%]), with 60.2% being sensitized to at least 1 indoor allergen and 53.3% to at least 1 outdoor allergen.

"Allergists have known the prevalence of allergies among asthmatic children is high at 60 to 80 percent, but it was thought allergies were not as common in asthmatic adults," Dr. Busse said in a news release. "These findings are important, and can help lead to proper diagnosis and treatment."

Although the literature suggests the prevalence of asthma may range from 3.5% to 7.5% in adults older than 60 years, this study finds that 4.5% of the NHANES 2005-2006 population aged 55 years and older had physician-diagnosed asthma, the researchers write. Asthma was more common in women with higher body mass indexes.

A limitation of the study was the inability to determine the age at which patients developed allergies, the authors note, but the strict diagnostic criteria for patient inclusion was a strength.

"In summary," the researchers write, "our study of the NHANES 2005-2006 database suggests that allergic sensitization in older patients with asthma is not uncommon and may differ only slightly from patients 20 to 40 years of age. Physicians providing care for older patients with asthma should consider testing for allergic sensitization and counseling about environmental control practices, particularly among those with poorly controlled asthma."

This research was supported in part by the National Institute of Environmental Health Sciences, National Institutes of Health. The authors have disclosed no relevant financial relationships.

Ann Allergy Asthma Immunol. 2013;110:247-252. Abstract