Characterization and Association Between Fat Mass and Fat-Free Mass Ratio with Clinical Characteristics in Asthmatic Adults

Introduction: The fat mass to fat free mass ratio (FM/FFM) assesses if the amount of FM is proportionally adequate for FFM in an individual, and have not yet been studied in asthma. Aims: To verify the associations of FM/FFM with clinical outcomes and to compare the clinical characteristics with lower and higher FM/FFM in individuals with asthma. Methods: 128 individuals were assessed regarding general and anthropometric data, lung function (spirometry), body composition (bioelectrical impedance analysis), physical activity in daily life (PADL – Actigraph activity monitor), and daily dose of inhaled medication. They were then classified in lower and higher FM/FFM according to the 50th percentile of the reference values. Results: Those with higher FM/FFM (n=75) used higher doses of inhaled corticosteroids, had worse lung function and fewer steps/day when compared to those with lower FM/FFM (P≤0.021). Higher FM/FFM was associated with worse lung function (R2:0.21 FEV1 in liters; R2:0.36 FVC in liters; R2:0.11 FVC %predicted; P<0.0001 for all), higher steps of pharmacological treatment (P=0.016, Cramer9s V=0.22) and worse level of PADL (P=0.009, V= 0.24). Those with higher FM/FFM are 3.21 (95%CI:1.17–8.78) times more likely to be physically inactive and 8.89 (1.23–64.08) times more likely to be in stages 4 and 5 of the disease pharmacological treatment. Conclusions: Adults with asthma and higher FM/FFM use higher doses of inhaled corticosteroids, have worse lung function and walk fewer steps/day when compared to those with lower FM/FFM. Higher FM/FFM is a determining factor of physical inactivity and of the highest steps of pharmacological treatment for asthma.