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

Abstract

Background: Obesity is a common comorbidity 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 (body mass index (BMI) ≤30 kg·m−2) versus healthy-weight (BMI <25 kg·m−2) subjects with asthma. Design: Databases including CINAHL (Cumulative Index to Nursing and Allied Health Literature), Cochrane, Embase and MEDLINE were searched up to July 2019 for English-language studies that recorded medication use or dose in obese and healthy-weight adults with asthma. A critical appraisal checklist was utilised for scrutinising methodological quality of eligible studies. Meta-analysis was performed and heterogeneity was examined with the use of the Chi-squared test. This review was conducted based on a published protocol (www.crd.york.ac.uk/PROSPERO CRD42020148671). Results: Meta-analysis showed that obese subjects are more likely to use asthma medications, including short-acting β2-agonists (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 (ICS) 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%). Forced expiratory volume in 1 s (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/forced vital capacity (FVC) ratio 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.