Predictor parameters for exercise intolerance in patients with chronic obstructive pulmonary disease (COPD)

Aim: The aim of this study was to investigate whether skeletal muscle and nutrition status parameters besides lung function parameters can predict exercise intolerance in COPD patients. Methods: The study recruited 140 patients with moderate (GOLD 2) and severe (GOLD 3) stable COPD. In all patients exercise tolerance was measured using a six-minute walk test (6-MWT). Lung function measurements (spirometry, lung diffusion), assessment of the level of dyspnea, fatigue, nutrition status and skeletal muscle function parameters were performed in all patients. Results: Age, peak expiratory flow (PEF), CO diffusion coefficient, general fatigue, waist circumference, suprailiac and abdominal skin folds, left inspiratory muscle strenght and thoracic vertebra index (OTT) were depicted as parameters which can explain 58,16% of the variability for the 6-MWT (m) results. The model for 6-MWT (%) explaining 48,60% variability of the test results depicted GOLD stage, body mass index, physical fatigue, waist circumference, suprailiac and abdominal skin folds, left inspiratory muscle strenght, OTT and lower limbs lenght as significant predictors. Discriminant analysis (excluding FVC and FEV 1 from the list of independent variables) depicted PEF, left inspiratory musle strenght, 6-MWT (%), fat free mass index, mental fatigue, difference in Borg dyspnea score and heart rate at the end of 6-MWT as significant predictor variables for the COPD severity stage with the 86,43% of diagnostic accuracy (GOLD 2 or GOLD 3). Conclusion: Our results suggest that skeletal muscle parameters and nutrition status parameters are independent predictor parameters for exercise intolerance and COPD severity stages.