Correlation between functional capacity and health-related quality of life in chronic obstructive pulmonary disease patient

Abstract

Introduction: Chronic obstructive pulmonary disease (COPD) is associated with pronounced exercise intolerance resulting in an impaired health-related quality of life [1]. Various interacting factors are potentially responsible for the mechanism(s) of exercise limitation with reduced maximal oxygen consumption (VO₂max), and as such not limited by any single component of the O₂ transport/utilization process, but rather by their collective quantitative interaction(s) [2]. Since most activities of daily living are performed in a non-incremental fashion and at a submaximal level of exertion, the 6-min walk distance test (6MWD) is representative of daily life activities and can therefore accurately reflect the functional capacity of patients [3]. The purpose of this study was to observe the correlation between functional capacity and health-related quality of life in CPOD patient.

Materials and methods: Sixty five men with moderate COPD (FEV1 55.8 ± 8.8%) were randomly assigned; age 65 ± 8.6 yrs; weight, 71.2 ± 8.3 kg; height, 169 ± 8.1 cm. Cardiopulmonary exercise test and 6MWD, were performed and we evaluated the health status through two questionnaires, St. George’s Respiratory Disease (SGRQ) and the Medical Outcomes 36-item Short Form Health Survey (SF-36). The study was approved by the Ethics Committee of the Garcia de Orta Hospital and all participants gave their informed consent.

Results: A significant positive correlation was found between (p < 0.01) VO₂peak (16.58 ± 6.3 mLkg⁻¹min⁻¹), 6MWD (496.7 ± 68.1 m) and the dimensions of physical function, physical role and vitality measured by SF-36, and significant negative correlations were found between the domains of symptoms, activity, impact and total assessed by the SGRQ (p < 0.01).

Discussion and conclusions: From the results analysis, it was possible to observe that the functional capacity, evaluated by the peak oxygen consumption or the distance measure of 6MWT, are correlated with health status measured by both specific and generic instruments.