Psychological factors mediating health-related quality of life in COPD

COPD is a chronic disease that has not only a high prevalence and social costs, but is tightly connected to a significant decrease of health-related quality of life (HRQoL). The aim of this study was to evaluate the comparative impact on HRQoL of two psychological factors (self-efficacy, optimism) vs. classical medical determinants (forced expiratory volume in 1 second (FEV1), peak expiratory flow (PEF), functional impairment). 26 women and 28 men, aged 45-64 years old (mean = 58.1; standard deviation = 9.7), diagnosed with COPD and with self-reported dyspnea requiring medication were administered COPD Self-Efficacy Scale, LOT-R (Life Orientation Test - Revised) to evaluate optimism, Quality of Well-Being (QWB) Scale, as an accepted measure of HRQoL and Functional Impairment Scale (FIS), used to assess the deterioration of functionality in respiratory diseases. Their respiratory parameters (FEV1, PEF) were also measured, via spirometry. Results showed that self-efficacy and optimism were positively correlated to HRQoL (r = .34 (p < .05) and r = .29 (p < .05), respectively). A reduced model that eliminated the direct influence of respiratory parameters on HRQoL proved to be equally satisfactory in terms of predictor value, compared to the full model (that contained all studied variables) (χ² = 0.067, ns). The functional impairment (FI) scores were inversely correlated with HRQoL (r = -.46, p < .01). These results have implications in considering self-efficacy and optimism as important factors when aiming HRQoL improvement in COPD, and for the inclusion of psychological interventions in the treatment plan of COPD patients. Abbreviations COPD = chronic obstructive pulmonary disease; WHO = World Health Organization; HRQoL = health-related quality of life; PEF = peak expiratory flow; FEV1 = forced expiratory flow in one second; LOT-R = Life Orientation Test - Revised; QWB = Quality of Well-Being; FI = functional impairment; SE = self-efficacy; Opt. = optimism.