Health-related quality of life
To measure HRQoL, the Clinical COPD Questionnaire
(CCQ) and the Chronic Respiratory Disease Questionnaire
Self-Administered Short version (CRQ-SAS) were used. The CCQ is a self-administered questionnaire consisting of 10 questions. Response options range from 0 (“no limitations/asymptomatic”) to 6 (“totally limited/extremely symptomatic”). The total score is computed by summing the scores and dividing the total score by the number of items. Higher scores indicate lower HRQoL.