On early sensitization to allergens and development of respiratory symptoms

Background Various studies have suggested that a sequence of events occurring in childhood may affect the development of asthma in susceptible individuals. We have investigated whether early childhood sensitization to aeroallergens is an important risk factor in the later development of asthma symptoms. Objective and methods In this study we examine this issue in children enrolled in the Tucson epidemiology study of obstructive airways disease, who had at least two allergen skin tests, one before and one after 8 years of age. Respiratory symptom data were available from 12 survey questionnaires, spanning a period of 20 years. During the first, sixth, seventh and eleventh surveys, skin tests were performed with commercially available allergens. Conclusion As compared with children who were sensitized after 8 years of age, children over 8 years who were sensitized to any allergen before age 8 years were significantly more likely to report shortness of breath with wheeze (SOBWZ), wheeze apart from colds or wheeze most days (OR = 4.1 SOBWZ; OR = 3.88 WZ apart from colds; and OR = 2.83 WZ most days). Children who were sensitized after 8 years were no more likely to have the symptoms described above than children who were never found to be sensitized. Based on these results we conclude that early allergic sensitization is a significant risk factor for later development of wheezy symptoms, where as late sensitization is not.