BACKGROUND The allergen skin prick test is the most representative diagnostic test for atopy, but its use has been limited because of the belief that skin reactivity decreases with aging.

OBJECTIVE To investigate skin reactivity and influencing factors in the elderly population.

METHODS This cross-sectional analysis included 854 subjects (aged ≥65 years) who participated in the Korean Longitudinal Study on Health and Aging cohort (September 2005 to August 2006) and underwent allergen skin prick tests. Skin prick tests were performed with 1 mg/mL of histamine and a panel of 12 aeroallergens that are common in Korea. The wheal diameters were measured and compared to identify the factors associated with skin reactivity.

RESULTS Older age and female sex were associated with reduced histamine skin reactivity in elderly subjects. This age-related decrease was apparent only among women, the reasons for which were not identified. In contrast to histamine, wheal response size induced by 2 major allergens, Dermatophagoides pteronyssinus and Dermatophagoides farinae, did not show sex differences and did not decrease with age among the subjects showing allergen-induced wheal size greater than 0 mm.

CONCLUSIONS This analysis demonstrates that age and sex can independently influence histamine skin reactivity among the elderly population. The allergen-induced wheal sizes did not decrease with age. The discrepancy between histamine and allergen skin reactivity may warrant further evaluation to redefine the cutoff value for the determination of a positive skin test result in elderly subjects.