Functioning and Psychological Status among Individuals with COPD

Abstract

We examined the link between functioning and psychological status among persons with chronic obstructive pulmonary disease (COPD), using measures of both general functional status and performance of life activities. 334 persons with COPD were interviewed by telephone. Functioning was assessed with two measures of difficulty with specific types of activities (self-care, recreational activities/hobbies) and a general measure of functional status (SF-12 Physical Component Score (PCS)). About 16.2% of the sample had SF-12 Mental Component Score (MCS) scores indicative of psychological distress (MCS < 35). In separate regression models, difficulty with self-care and recreational activities was associated with an increased likelihood of distress (self-care: OR=2.9, 95%CI 1.3, 6.6; recreation: OR=7.5 [2.4, 23.7]), while PCS scores were not. In a model including all three predictors, difficulty with recreation was strongly associated with distress (OR=7.7 [2.1, 29.2]), difficulty with self-care was less strongly associated with distress (OR=2.1 [0.8, 5.5]), and PCS did not contribute significantly to the predictive ability of the model. However, low functioning as measured by the PCS was a significant risk factor for difficulty performing activities. Measures of activity difficulty were independent predictors of psychological distress, while general physical function was not. Poor general physical function was a risk factor for activity difficulties, suggesting an indirect relationship between low PCS and psychological distress, with activity difficulties as the intermediate variable.