Reduced Skeletal Muscle Mass Is Associated with an Increased Risk of Asthma Control and Exacerbation

Background: Skeletal muscle mass (SMM) has been suggested to be associated with multiple health-related outcomes. However, the potential influence of SMM on asthma has not been largely explored. Objective: To study the association between SMM and clinical features of asthma, including asthma control and exacerbation, and to construct a model based on SMM to predict the risk of asthma exacerbation (AEx). Methods: In this prospective cohort study, we consecutively recruited patients with asthma (n = 334), classified as the SMM (Normal) group (n = 223), SMM (Low) group (n = 88), and SMM (High) group (n = 23). We investigated the association between SMM and clinical asthma characteristics and explored the association between SMM and asthma control and AEx within a 12-month follow-up period. Based on SMM, an exacerbation prediction model was developed, and the overall performance was externally validated in an independent cohort (n = 157). Results: Compared with the SMM (Normal) group, SMM (Low) group exhibited more airway obstruction and worse asthma control, while SMM (High) group had a reduced eosinophil percentage in induced sputum. Furthermore, SMM (Low) group was at a significantly increased risk of moderate-to-severe exacerbation compared with the SMM (Normal) group (relative risk (adjusted) 2.02 [95% confidence interval (CI), 1.35–2.68]; p = 0.002). In addition, a model involving SMM was developed which predicted AEx (area under the curve: 0.750, 95% CI: 0.691–0.810). Conclusions: Low SMM was an independent risk factor for future AEx. Furthermore, a model involving SMM for predicting the risk of AEx in patients with asthma indicated that assessment of SMM has potential clinical implications for asthma management.