Skeletal Muscle Adiposity and Lung Function Trajectory in the Severe Asthma Research Program

Area of Science:

• Pulmonary Medicine
• Metabolic Health
• Imaging Science

Background:

• Extrapulmonary manifestations in asthma, such as fatty infiltration, may indicate systemic inflammation.
• These manifestations can impact asthma severity and lung function.
• Skeletal muscle adiposity is an understudied extrapulmonary feature in asthma.

Purpose of the Study:

• To investigate whether skeletal muscle adiposity predicts the trajectory of lung function in adults with asthma.
• To explore potential sex differences in this association.

Main Methods:

• Utilized data from the Severe Asthma Research Program III (SARP III) cohort.
• Assessed baseline skeletal muscle adiposity using paraspinous muscle density (PSMD) from computed tomography scans.
• Employed linear mixed-effects models to analyze the association between PSMD and longitudinal FEV1% predicted over a median of 5 years, stratified by sex.

Main Results:

• Adults with asthma exhibited significantly lower PSMD (greater muscle fat infiltration) compared to healthy controls.
• Lower baseline PSMD was a significant predictor of lung function decline in women with asthma (β = -0.47 Δ slope per 10-HU decrease; P = 0.03).
• No significant association was found between PSMD and lung function trajectory in men with asthma (P = 0.77).

Conclusions:

• Individuals with asthma demonstrate increased skeletal muscle fat infiltration compared to controls.
• Baseline muscle adiposity predicts lung function decline specifically in women with asthma.
• These findings suggest that metabolic dysfunction plays a crucial role in the progression of lung function impairment in asthma, particularly in women.