Association between interpersonal and environmental factors and health-related quality of life in patients with chronic obstructive pulmonary disease (COPD)

Background: Reports on the determinants of health-related quality of life (HRQoL) in COPD patients have mostly been focused on clinical factors. Aim: To assess the relationship between interpersonal and environmental factors, and HRQoL in COPD patients. Methods: In this cross-sectional study recruiting 407 moderate-to-severe COPD patients from five Catalan municipalities, HRQoL was assessed using COPD Assessment Test (CAT). Interpersonal factors such as number of people in the household, grandparenting and walking the dog, were assessed by questionnaire. Neighbourhood deprivation was assessed using the census-based Urban Vulnerability Index 2001. Residential surrounding greenness was determined using satellite-derived Normalized Difference Vegetation Index (NDVI). Residential proximity was defined for those living within a recommended 300 m distance to green or blue spaces. Results: 85% patients were male (mean age 69±9 years) with a post-bronchodilator FEV1 of 56±17 %pred. In the linear model adjusted for body mass index (BMI), FEV1%pred and 6-min walk distance, living alone was related to a worse HRQoL (coefficient β: 2.85; 95% confidence interval (CI): 0.75, 4.95) and living close to a green or blue space was marginally associated with a better HRQoL (β: -1.2; 95%CI: -2.6, 0.12). Other interpersonal and environmental determinants were not associated with HRQoL in COPD. Conclusions: Living alone and lack of proximity to green or blue space can negatively affect the HRQoL in COPD patients.