Risk factors for hospital admission for asthma from childhood to young adulthood: A longitudinal population study

Background: Predictors of hospital admissions for asthma in children and young adults in a general population are not well defined, because most studies have used selected subpopulations. Objective: The purpose of this investigation was to determine risk factors for single and multiple hospital admissions for asthma. Methods: The members of a population-based, unselected birth cohort of 1037 New Zealanders answered questionnaires and underwent lung function, airway responsiveness, and allergy testing on 7 occasions to the age of 26 years. Results: Among the 766 study members (74% of the cohort) who reported wheezing symptoms ever by the age of 26 years, 136 hospitalizations were reported by 62 individuals (8.3% of those at risk, 6.2% of the total cohort). Only 55 of these 136 admissions involved children less than 9 years of age; admissions continued to occur between the ages of 9 and 18 years (40 admissions) and at >18 years (41 admissions). Those admitted were predominantly male, had earlier ages of onset of symptoms, were more atopic, and had more airway hyperresponsiveness to methacholine than those not admitted. Frequent symptoms and low lung function were evident among the 45 study members with single admissions and even more evident among the 17 study members with multiple (2-10) admissions. Conclusions: A surprisingly large fraction of this unselected population experienced hospitalization for asthma during the 26-year follow-up, many being admitted in later childhood, adolescence, and early adulthood. Clinical characteristics and markers of severity, including frequent respiratory symptoms, airway hyperresponsiveness, atopy, and low lung function, identify those at high risk for hospitalization for asthma, particularly with respect to multiple admissions.