All patients had complete demographic data recorded, including age, duration of symptoms, and full smoking and medical history. Full lung function, including reversibility testing with 400 μg inhaled albuterol, was also performed according to the American Thoracic Society/European Respiratory Society consensus guidelines.22‐26 Health status and symptom scores were measured using the St. George Respiratory Questionnaire (University of London; London, England),27 a two-part questionnaire measuring recollection of symptoms and assessment of current activity and impact, in which scores are expressed as a percentage of overall impairment, with zero indicating best possible health status and 100 indicating worst possible health status; the Chronic Respiratory Disease Interviewer-Administered Questionnaire (McMaster University; Hamilton, Ontario, Canada),28 which measures disease-specific quality of life with scores ranging from 1 to 7, with a higher score indicating a better quality of life for the domains of emotion, mastery, dyspnea, and fatigue; and the visual analog scale (VAS) for the domains of cough, breathlessness, sputum production, and sputum purulence, which consists of a 100-mm line for each measured domain, with “no symptoms” at one end and “the worst symptoms ever” at the other.29 Body composition was calculated using BMI.30 Spontaneous or induced sputum was collected and analyzed for bacteria,31 including colony-forming units.32 Quantitative real-time polymerase chain reaction was used to estimate the total bacterial load based on the abundance of 16S ribosomal subunit encoding genes. In brief, bacterial DNA was extracted from homogenized sputum according to the manufacturer’s instructions, using the QIAmp DNA Mini Kit assay (QIAGEN, Ltd; Hilden, Germany). Quantification of the total bacterial load was performed using the SYBR green assay (PE Applied Biosystems; Warrington, England). Sputum samples were then processed to produce cytospins for cell differential.33,34 Venous blood was collected for assessment of peripheral blood differential cell counts and serum C-reactive protein.