Do obese asthmatics have a worse bronchodilator response?

Abstract

Introduction: Despite recent advances in asthma treatment, there still remain a significant proportion of asthmatics whose asthma is poorly controlled. Previous studies have shown that compared to non-obese asthmatics, obese asthmatics appeared to have a poorer clinical response to inhaled corticosteroids. Whether an alternative emphasis on enhanced bronchodilator therapy would be effective remains unknown. An understanding of bronchodilator response in this phenotype may provide further insight. Aim: The aim was to compare the bronchodilator response using spirometry (FEV1 or FVC change) between obese and non-obese asthmatics in Singapore. Methods: This was a retrospective study of all subjects with confirmed asthma who underwent spirometry (pre and postbronchodilator) at Changi General Hospital, Singapore from 1st Jan 2012 to 31st Dec 2013. Subjects with other concomitant chronic lung diseases or smoking history of >10 packyears were excluded. Results: 259 subjects were included in the study of which 24.3% were obese. There was no statistically significant difference between obese and non-obese asthmatics in prebronchodilator FEV1 (%predicted) (p=0.58), FVC (%predicted) (p=0.22) and FEV1/FVC (P=0.29). There was a statistically significant difference in FEV1 change between obese (0.13±0.16L) and non-obese asthmatics (0.20±0.19L) (P=0.003). However, this difference was not seen in FVC change (P=1.00). A lower FEV1 was still seen in obese asthmatics after adjusted for age, gender and race with multiple linear regression (p=0.01). Conclusions: Obese asthmatics had a reduced bronchodilator response on spirometry (FEV1 change) compared to non-obese asthmatics in our study and this may suggest a reduced response to long acting s2 agonist.