Association of asthma and smoking with lung function impairment in adolescence and early adulthood; the Isle of Wight Birth Cohort Study.

We investigated associations of asthma and smoking with lung function and airway reversibility from childhood to early adulthood. The population-based Isle of Wight Birth Cohort (n=1456) was assessed at birth, 1, 2, 4, 10, 18 and 26-years. Asthma was defined as physician diagnosis plus current wheeze and/or treatment. Spirometry was conducted at 10 (n=981), 18 (n=839) and 26 years (n=547). Individuals were subdivided into: non-smokers without asthma, non-smokers with asthma, smokers without asthma, and smokers with asthma, based on asthma and smoking status at age 26. Their lung function trajectories from 10 to 26 years were examined using longitudinal models. Non-smokers with asthma had smaller FEV1, FEF25–75 and FEV1/FVC ratio compared to non-smokers without asthma at age 10 and 18, with differences reduced after bronchodilator (pre-bronchodilator FEV1 at 26-years: 3.75 L versus 4.02 L, p Lung function deficits associated with asthma and smoking occur early in life. They are not fully responsive to bronchodilator indicating a risk for long term lung health, which highlights the need to institute preventive measures in adolescence and early adult life before irreversible damage occurs.