Airway Bacterial Colonization in COPD under the Therapy of Inhaled Corticosteroid/long-acting β2 Agonist-The Relationship with COPD Assessment Test

Abstract

Airway bacterial colonization is often seen as a surrogate of acute exacerbation of chronic obstructive pulmonary disease (COPD). The COPD assessment test (CAT) can assess the disease status and exacerbation. The relationship between airway bacterial colonization and disease status evaluated by the CAT in moderate to severe COPD under the treatment of inhaled corticosteroid (ICS) and long-acting β2 agonist (LABA) is unclear. The study was conducted from February 2011 to April 2012. Moderate to severe COPD patients with ICS and LABA combination therapy were included in this study. All participants produced sputum for bacterial cultures after sputum induction and underwent CAT and spirometry at the start of the study and every three months until the end of the study period. Seventeen participants made a total of 37 visits. Thirty-five percent of the sputum cultures yielded potentially pathogenic microorganisms (PPM), implying positive cultures. The most common pathogens were Haemophilus species. Forty-four percent of the visits with a CAT score of more than 20 had positive cultures, whereas 25% of the visits with a CAT score of 20 or less had positive cultures. Sixty percent of the follow-ups with an increment of more than two from the baseline CAT score had positive cultures, whereas only 30% of the follow-ups with an increment of two units or less had positive cultures. Subjects with baseline CAT scores of more than 20 or a two unit increment from baseline score might have a higher risk of PPM colonization.