Physical activity heterogeneity in COPD; meaningful analysis of data

INTRODUCTION: Physical Activity (PA) is an important factor to measure in patients with COPD (chronic obstructive pulmonary disease) because low PA is associated with poorer long-term outcomes. However, the optimum way to analyse and report PA data; or if PA is associated with other clinical characteristics, is unknown in COPD. METHOD: We explored PA within a secondary care COPD cohort (COPDMAP). Sensewear Armband PA monitors (SWM) were used to obtain readings over 7 days for 55 patients. Clinical characteristics including spirometry were also recorded. PA variables were used in a factor analysis to determine underlying patterns of activity within the cohort and verified in two further separate cohorts. RESULTS: PA variables were positively correlated with each other (p 1. 9General Daily Activity9, 9GDA9 associated with the number of 2 min bouts of moderate activity in 24hr, factor loading (FL) =0.94. 2. 9Purposeful Physical Activity9, 9PPA9 associated with number of 20 min bouts of moderate activity per 24 hours, FL=0.84. CONCLUSIONS: We have found two distinct types of activity within a secondary care COPD cohort; that of 9General Daily Activity9 9GDA9 and 9Purposeful Physical Activity9, 9PPA9. These have distinct clinical associates.