Testing the functional status model in patients with chronic obstructive pulmonary disease

BACKGROUND: Patients with chronic obstructive pulmonary disease usually experience gradual functional status degradation, especially dyspnoea, which may affect their daily activities and, eventually, quality of life. A full understanding of both their physiological and psychological functional status is therefore beneficial for effective treatment and helping patients regain or maintain control of their lives. METHOD: Based on a non-experimental research design, 138 patients to test a hypothesized model of functional status in patients with chronic obstructive pulmonary disease, using structural equation modelling, were recruited from a medical center. Data were collected using questionnaires, 6-minute walking distance measurement, and pulmonary function test results recorded in patients' medical records. The proposed functional status model incorporated the exogenous variables disease severity and dyspnoea, and the endogenous variables age, exercise tolerance, fatigue, depression, anxiety, health perception and functional performance. Structural equation modelling with the lisrel software was used to establish a functional status model with those exogenous and endogenous variables. RESULTS: The results indicated a good fit between the proposed functional status model and the data collected chi(2) = 8.84, P = 0.64, chi(2)/d.f. = 0.80, Goodness of Fit Index (GFI) = 0.98, adjusted GFI (AGFI) = 0.95, root mean square residual (RMR) = 0.04, Critical N (CN) = 384.26]. Coefficients for paths in the functional status model all demonstrated statistical significance. CONCLUSION: The functional status model was shown to consist of functional performance, functional capacity and other concepts, including disease severity, dyspnoea, age, exercise tolerance, fatigue, depression, anxiety and health perception. These results can be used to develop a suitable functional status model for chronic obstructive pulmonary disease, and could act as a reference for formulating future strategies and intervention procedures for further development of functional status.