Asthma medication use in obese and healthy weight asthma: systematic review/meta-analysis

Background Obesity is a common co-morbidity in asthma and associated with poorer asthma control, more frequent/severe exacerbations, and reduced response to asthma pharmacotherapy.

Objective This review aims to compare use of all classes of asthma medications in obese (BMI≥30 kg·m⁻²) versus healthy weight (BMI<25 kg·m⁻²) subjects with asthma.

Design Databases including CINAHL, Cochrane, EMBASE, and MEDLINE were searched for English language studies up to July 2019 that recorded medication use or dose in obese and healthy weight adults with asthma. A critical appraisal checklist was utilised for scrutinising methodologic quality of eligible studies. Meta-analysis was performed and heterogeneity was examined with the use of the χ² test. This review was conducted based on a published protocol (PROSPERO: CRD42020148671).

Results Meta-analysis showed that obese subjects are more likely to use asthma medications including; short-acting β₂-agonists [odds ratio (OR)=1.75; 95% CI:1.17, 2.60; p=0.006, I²=41%] and maintenance oral corticosteroids (OR=1.86; 95% CI:1.49, 2.31; p<0.001, I²=0%) compared to healthy weight subjects. Inhaled corticosteroid dose (µg·day⁻¹) was significantly higher in obese subjects (mean difference=208.14; 95% CI:107.01, 309.27; p<0.001, I²=74%). FEV₁% predicted was significantly lower in obese subjects (mean difference=−5.32%; 95% CI:−6.75, −3.89; p<0.001, I²=42%), however, no significant differences were observed in FEV₁/FVC% between groups.

Conclusions We found that obese subjects with asthma have higher use of all included asthma medication classes and higher ICS doses than healthy weight asthma subjects, despite lower FEV₁ and a similar FEV₁/FVC%. A better understanding of the factors driving increased medication use is required to improve outcomes in this subgroup of asthmatics.