Bacterial Colonization in COPD in View of CAT Under ICS+LABA Therapy

Patients with COPD (chronic obstructive pulmonary disease) suffer from episodes of acute exacerbations leading to additional morbidity and mortality, and also a further decline in lung function. It has been well-established that bacterial colonization is prevalent in COPD, especially in moderate to severe COPD, and airway bacterial colonization is known to play an important role in the development of pneumonia and exacerbations. On the other way, inhaled corticosteroid (ICS) and long acting β2 agonist (LABA) were recommended in the treatment of moderate to severe COPD. Though there were some evidences that ICS had some protective effects on airway mucosa against bacteria invasion, the locally immunosuppressive effects of ICS is still a concern. Indeed, the incidence of pneumonia was higher than the control group, not only in the Towards a Revolution in COPD Health (TORCH) study but also in various studies and meta-analyses.We hypothesized that airway bacteria colonization is associated with disease severity, and that disease status can be identified by CAT (COPD assessment test)scores and changes of CAT scores. We therefore conducted this prospective, observational study in which CAT scores and sputum cultures were assessed in moderate to severe COPD patients with the combination therapy of ICS and LABA every three months during the study period. The primary end-point is the condition of potential pathogenic microorganisms (PPM) colonization in view of CAT scores. The second end-point was the changes of PPM colonization in association with CAT changes during follow-up. By the mean of CAT follow-up, it could possibly provide a surrogate about the risk of exacerbation and pneumonia under the combination therapy of ICS and LABA.