Low incidence and high remission of allergic sensitization among adults

Prospective studies on the incidence and remission of allergic sensitization among adults are rare.

We sought to assess the incidence, remission, risk factors, and prevalence of allergic sensitization in relation to aging over a 10-year period.

In 1994, a sample of 664 adults (68% of invited) participated in clinical examinations, including a structured interview and skin prick tests (SPTs). The sample was randomly selected from a large questionnaire survey in Northern Sweden. In 2004, 555 subjects (93% of invited) were re-examined by using the same methods as in 1994. IgE levels were also measured in 2004.

In 1994, the prevalence of any positive SPT response was significantly related to age, with the highest prevalence (55%) in subjects aged 20 to 29 years and the lowest prevalence (26%) in subjects aged 50 to 60 years. A similar age-related prevalence was found in 2004, and sensitization to pollen and pets was most common in both years. The results of the SPTs were verified by means of specific IgE measurement. The incidence of any positive SPT response was low. Only 9 subjects had any positive SPT response (ie, a cumulative incidence of 5% over 10 years). Remission was greater (ie, 32% over 10 years). The main risk factors for allergic sensitization were young age and a family history of allergy. Having had furred animals at home during childhood was negatively related to specific IgE levels.

The low incidence and high remission in adulthood explain the decreasing prevalence of allergic sensitization by age. Thus the low prevalence of allergic sensitization among the elderly found in cross-sectional studies is an effect of normal aging and not primarily a birth cohort effect.