An explanatory model of functional status in chronic obstructive pulmonary disease.

The purpose of this study was to test an explanatory model of variables influencing functional status in chronic obstructive pulmonary disease (COPD). The sample consisted of 104 patients with COPD (85 males, 19 females, mean age = 65.5, SD = 7.7). The variables in the initial model were age, length of illness, pulmonary function, oxygen desaturation during exercise, dyspnea, depressed mood, anxiety, self-esteem, exercise capacity, and functional status. Path analysis revealed that exercise capacity (beta = .337, p = .0007), dyspnea (beta = .324, p = .0009), and depressed mood (beta = -.204, p = .011) directly influenced functional status Dyspnea (beta = .488, p < .0001), depression (beta = -.217, p = .003), and pulmonary function (beta = .421, p < .0001) indirectly influenced functional status through exercise capacity. Self-esteem (beta = -.492, p = .004) and anxiety (beta = .696, p < .0001) indirectly influenced functional status through depressed mood. The findings of this study suggest that efforts to improve functional status of individuals with COPD should focus on interventions that influence exercise capacity, dyspnea, anxiety, and depressed mood.