Airway Obstruction Worsens in Young Adults with Asthma Who Become Obese

Background Few studies have examined how developing obesity in early adulthood affects the course of asthma. Objective We analyzed lung function and asthma impairment and risk among nonobese children with asthma, comparing those who were obese in young adulthood with those who remained nonobese. Methods We carried out the post hoc analysis of 771 subjects with mild to moderate asthma who were not obese (pediatric definition, body mass index [BMI] 2 ) on at least 1 visit (median number of visits when obese = 4, IQR 2-7). Results Compared with participants who were nonobese (BMI 23.4 ± 2.6 kg/m 2 ), those who became obese (BMI 31.5 ± 3.8 kg/m 2 ) had significant decreases in forced expiratory volume in the first second (FEV 1 )/forced vital capacity (FVC) ( P 1 ( P  = .001), without differences in FVC ( P  = .15) during visits at ages 20 years or more. For each unit increase of BMI, FEV 1 percent predicted decreased by 0.29 ( P  = .0009). The relationship between BMI and lung function was not confounded by sex or BMI at baseline. Asthma impairment (symptom scores) and risk (prednisone use) did not differ between the 2 groups. Conclusion Becoming obese in early adulthood was associated with increased airway obstruction, without impact on asthma impairment or risk.