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

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 kgm(-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 beta(2)-agonists (OR 1.75, 95% CI 1.17-2.60; p=0.006, I-2 =41%) and maintenance oral corticosteroids (OR 1.86, 95% CI 1.49-2.31; p<0.001, I-2 =0%) compared to healthy-weight subjects. Inhaled corticosteroid (ICS) dose (mu g.day(-1)) was significantly higher in obese subjects (mean difference 208.14, 95% CI 107.01-309.27; p<0.001, I-2 =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, I-2 =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.

Automated summary

Obese asthma subjects are more likely to use asthma medications, including maintenance oral corticosteroids, and have higher inhaled corticosteroid doses compared to healthy-weight asthma subjects. Despite lower FEV1, there were no significant differences in FEV1/FVC ratio between the two groups.