The six minute walk distance is the best predictor of physical activity in severe COPD patients

Abstract

Physical activity is the most important predictor of mortality in subjects with chronic obstructive pulmonary disease (COPD). To investigate which factors are related to physical activity in COPD patients who desaturate (SpO 2 ≤ 88% and a fall in SpO 2 ≥ 4%) during a six minute walk distance (6MWD) assessment breathing ambient air. The following values were measured in 64 COPD patients (33 females); physical activity (steps per day, MiniMod), 6MWD, spirometry (FEV 1 , FVC), C-reactive protein (P-CRP), dyspnea (mMRC), symptoms (CAT), resting SpO 2 and decrease in SpO 2 during the walking test. Patients had a mean age of 69.5±8.8 years and a mean post bronchodilator FEV 1 % predicted of 40.8±15.9. They walked on average 3768±2213 steps per day and 6MWD was 363.0±103.6 m. 6MWD was the variable with the highest correlation with physical activity (figure 1). Other variables significantly correlated with physical activity were mMRC and FEV 1 (L). Six minute walking distance was the variable that had the best correlation with physical activity in patients with COPD who desaturate during exercise. This result is consistent with the view that the 6MWD is reflective of the level of activity that the patient adopts in everyday life. Figure 1. R 2 value of simple linear regression model between each parameters and steps per day. * and ** represented statistical significance at p