Factor analysis of quality of life, dyspnea, and physiologic variables in patients with chronic obstructive pulmonary disease before and after rehabilitation

Objective: To identify the relationships between quality of life (QOL) and the clinical state using factor analysis pre- and postrehabilitation. Patients with chronic obstructive pulmonary disease (COPD) suffer from a significant physiologic impairment associated with an altered QOL. Comprehensive rehabilitative programs, including exercise training, have beneficial effects on exercise tolerance and QOL for these patients. Design: Factor analysis (n = 6) was conducted using the data of 32 patients with COPD. Patients had been evaluated for QOL using the Nottingham Health Profile (NHP), spirometric values, dyspnea, and the variables assessed by an incremental exercise test at three levels of activity. All measurements were obtained pre- and postrehabilitation. Results: Factor analysis showed that the following two factors characterize the pathophysiologic condition of patients with COPD: (1) the specific cardiorespiratory responses to incremental exercise test and the spirometric values; and (2) the QOL results. The factor analysis results differed with the testing time (pre, post) and the level of activity. Conclusions: QOL, as evaluated by a generic questionnaire and the clinical state of patients with COPD, was independent; this independence characterized the pathophysiologic condition of our patients. Our results reinforce the usefulness of different types of evaluation, especially pre- and postrehabilitation, because they reflect independent benefits used to understand the success and follow-up of rehabilitative programs.