A MULTIDIMENSIONAL MODEL OF PHYSICAL HEALTH IN PATIENTS WITH COPD

Background.Chronic obstructive pulmonary disease (COPD) is a chronic, inflammatory disease associated significant health burden.  Dyspnea and fatigue are highly prevalent symptoms in COPD, and these symptoms may interfere with daily activity and contribute to disability among patients with COPD.  Identifying factors that contributes to dyspnea and fatigue may help enhance approaches to disease treatment and symptoms management.  However, the majority of research studying symptoms of COPD used linear approaches to predict fatigue or dyspnea, and the findings are inconsistent.  A multidimensional model incorporating disease severity, psychological wellbeing, physical functioning as factors that contributes to symptoms of dyspnea and fatigue in patients with COPD is warranted.

Purposes/Aims.The purpose of this project is to examine a model describing the relations among disease severity, psychological wellbeing, and physical functioning as factors that contributes to dyspnea and fatigue in patients with moderate to very severe COPD.

Methods:This in-progress project is part of an ongoing longitudinal observational study of the biological causes and functional consequences of depression in patients with COPD.  We plan to use a cross-sectional design with baseline data. Structural equation modeling with maximum likelihood method of estimation will be use to test hypotheses exploring the relations among disease severity, psychological wellbeing, physical functioning, dyspnea, and fatigue. Symptoms of dyspnea and fatigue were measured by the Chronic Respiratory Disease Questionnaire. Disease severity was measured with spirometry (forced expiratory volume in 1 second % predicted) and the number of co-morbidities. Psychological well-being was measured by the Hospital Anxiety and Depression Scale. Physical functioning was measured by the six-minute walk test.

Results and Implications. We expect that the final structural equation model fit the data, and the specified factors (disease severity, psychological wellbeing, and physical function) explain a large portion of variance in fatigue and dyspnea. Exploratory analyses will be conducted to examine interrelationships among the factors, and potential indirect effects of factors on fatigue and dyspnea as mediated by other factors. The results of this study will shed light on the factors that directly contribute to dyspnea and fatigue severity in patients with COPD, and potentially help design future interventions to better manage symptoms.