Wheezing and bronchial hyper-responsiveness in early childhood as predictors of newly diagnosed asthma in early adulthood: a longitudinal birth-cohort study.

BACKGROUND

Incidence of asthma increases during early adulthood. We aimed to estimate the contributions of sex and early life factors to asthma diagnosed in young adults.

METHODS

1246 healthy newborn babies were enrolled in the Tucson Children's Respiratory Study. Parental characteristics, early-life wheezing phenotypes, airway function, and bronchial hyper-responsiveness to cold dry air and sensitisation to Alternaria alternata were determined before age 6 years. Physician-diagnosed asthma, both chronic and newly diagnosed, and airway function were recorded at age 22 years.

FINDINGS: Of 1246 babies enrolled, 849 had follow-up data at 22 years. Average incidence of asthma at age 16-22 years was 12.6 per thousand person-years. 49 (27%) of all 181 cases of active asthma at 22 years were newly diagnosed, of which 35 (71%) were women. Asthma remittance by 22 years was higher in men than in women (multinomial odds ratio [M-OR] 2.0, 95% CI 1.2-3.2, p=0.008). Age at diagnosis was linearly associated with the ratio of forced expiratory volume at 1 s to forced vital capacity at age 22 years. Factors independently associated with chronic asthma at 22 years included onset at 6 years (7.4, 3.9-14.0) and persistent wheezing (14.0, 6.8-28.0) in early life, sensitisation to A alternata (3.6, 2.1-6.4), low airway function at age 6 years (2.1, 1.1-3.9), and bronchial hyper-responsiveness at 6 years (4.5, 1.9-10.0). Bronchial hyper-responsiveness (6.9, 2.3-21.0), low airway function at 6 years (2.8, 1.1-6.9), and late-onset (4.6, 1.7-12.0) and persistent wheezing (4.0, 1.2-14.0) predicted newly diagnosed asthma at age 22 years.

INTERPRETATION: Asthma with onset in early adulthood has its origins in early childhood.