Visceral obesity is associated with clinical and inflammatory features of asthma: A prospective cohort study

Background: Although studies have consistently linked obesity and asthma, the potential influence of visceral obesity on asthma has not been well investigated. Objective: To study the associations of visceral fat area (VFA) and clinical and inflammatory features of asthma and to further explore the effects of VFA on the future risk of asthma exacerbation. Methods: A 12-month prospective cohort study based on the Australasian Severe Asthma Network was designed to observe patients with stable asthma grouped by the median value of VFA. The clinical and inflammatory features of asthma were compared between the low VFA (VFA(low)) and high VFA (VFA(high)) groups. Relationships between VFA and clinical and inflammatory features of asthma were analyzed by using correlation analysis. Univariate and multivariable negative binomial regression analyses were performed to investigate the association of VFA with exacerbations within a 12-month follow-up period. Results: The patients in the VFA(high) group were older and had a longer asthma duration. Interleukin (IL) 6 and IL-8 in sputum were higher, whereas fractional exhaled nitric oxide (FeNO) and blood eosinophils were lower in the VFA(high) group. Gender-differentiated correlations of VFA with clinical and inflammatory variables were observed in age, FeNO, immunoglobulin E, blood total white cells and neutrophils, and sputum IL-1 beta and IL-8. Furthermore, compared with the VFA(low) group, the VFA(high) group was at significantly increased risk of moderate-to-severe exacerbations (adjusted incidence rate ratio [IRR] 1.55 [95% confidence interval {CI}, 1.06-2.28; p = 0.025), severe exacerbations (adjusted IRR 2.25 [95% CI, 1.26-4.04]; p = 0.007), and emergency visits (adjusted IRR 5.33 [95% CI, 1.78-17.16]; p = 0.003). Conclusion: The level of VFA was associated with specific clinical and inflammatory characteristics of asthma. Furthermore, VFA, as an independent risk factor, was associated with an increased risk of exacerbations. It indicated that VFA would provide more potential clinical implications for asthma management.