Lean muscle mass and bone mineral content are predictors of lung function in ex-smokers with or without COPD

Abstract

Objectives: To examine body composition in relation to lung function, inflammation and physical activity in ex-smokers with or without Chronic Obstructive Pulmonary Disease (COPD).Methods: One hundered and seven (107) adults, ≥ 35 years (16 never smokers, 68 ex-smokers without COPD, 23 ex-smokers with COPD) were recruited. Body composition (dual energy x-ray absorptiometry), spirometry, airway (sputum cell counts) inflammation, systemic inflammation (CRP, IL-6, leptin), physical activity and quality of life were assessed. Partial correlation, linear and multiple regression analyses were performed to identify predictors of lung function and associations with body composition.Results: Lean muscle mass (LMM) and bone mineral content (BMC) were positively associated with FEV 1 (r = 0.447, p < 0.001 and r = 0.335, p < 0.01 respectively) and FVC (r = 0.507, p < 0.001 and r = 0.234, p < 0.05 respectively). Fat mass was negatively associated with FEV 1 (r = -0.443, p < 0.001) and FVC (r = -0.518, p < 0.001). CRP, IL-6 and leptin were negatively associated with FEV 1 and FVC. In multiple regression models, LMM and BMC remained significant predictors of FEV 1 , FVC and FEV 1 /FVC. Discussion: LMM and BMC are positively associated with lung function in ex-smokers. Physical activity and systemic inflammation were negatively associated with body composition. Strategies improving exercise capacity and reducing systemic inflammation may improve body composition and outcomes in ex-smokers.