On early sensitization to allergens and development of respiratory symptoms

Background Various studies have suggested that a sequence of events occurri ng in childhood may affect the development of asthma in susceptible individ uals. We have investigated whether early childhood sensitization to aeroall ergens is an important risk factor in the later development of asthma sympt oms. Objective and methods In this study we examine this issue in children enrol led in the Tucson epidemiology study of obstructive airways disease, who ha d at least two allergen skin tests, one before and one after 8 years of age . Respiratory symptom data were available from 12 survey questionnaires, sp anning 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 a ge, children over 8 years who were sensitized to any allergen before age 8 years were significantly more likely to report shortness of breath with whe eze (SOBWZ), wheeze apart from colds or wheeze most days (OR = 4.1 SOBWZ; O R = 3.88 WZ apart from colds; and OR = 2.83 WZ most days). Children who wer e sensitized after 8 years were no more likely to have the symptoms describ ed above than children who were never found to be sensitized. Based on thes e results we conclude that early allergic sensitization is a significant ri sk factor for later development of wheezy symptoms, where as late sensitiza tion is not.