Study objectives: To test the hypothesis that the presence of sensitization to indoor allergens is associated with increased severity of airway obstruction in elderly subjects with asthma.
Design: Cohort study of subjects enrolled in a public hospital asthma clinic.
Setting: Asthma clinic in a municipal public hospital serving an indigent population in New York City.
Patients: Subjects aged ≥ 60 years with asthma who were enrolled in the Bellevue Hospital Asthma Clinic. Total serum IgE and allergen-specific IgE measurements were performed in a cohort of elderly never-smokers who had asthma (45 patients) who had undergone spirometry before and after bronchodilator (BD) therapy.
Measurements and results: The results of radioallergosorbent tests demonstrated that most subjects (ie, 60%) were sensitized to at least one allergen, with many sensitized to at least one indoor allergen. Cockroach (CR) was the most common allergen to which subjects were sensitized, with 47% displaying an elevated serum-specific IgE level. Fewer subjects were sensitized to dust mite, cat, dog, or ragweed. Subjects sensitized to CR (CR+) had greater reductions in airflow compared to subjects not sensitized to CR (CR−) [64 ± 4.4% predicted vs 77.1 ± 4.1% predicted FEV1, respectively; p < 0.05]. Following BD administration, only 29% of CR+ subjects achieved a normal post-BD FEV1 compared to 58% of CR− subjects. Lung volume measurements differed between CR+ and CR− subjects, with a greater elevation of functional residual capacity in CR+ subjects.
Conclusion: In a population of elderly urban patients with asthma, the presence of CR-specific serum IgE is associated with more severe asthma, as reflected by an increase in airway obstruction and hyperinflation.