Chronic Bronchial Infection Is Associated with More Rapid Lung Function Decline in Chronic Obstructive Pulmonary Disease

Rationale: Some patients with chronic obstructive pulmonary disease ( COPD) suffer accelerated lung function (forced expiratory volume in 1 second [FEV1]) decline over time. Objectives: To investigate the relationship between chronic bronchial infection (CBI) and, in particular, the isolation of Pseudomonas aeruginosa (PA), and FEV1 decline in COPD. Methods: Post-hoc analysis of a prospective cohort of 201 patients with COPD followed up every 3-6 months for 84 months. CBI was defined as >= 3 sputum positive cultures of the same pathogenic micro-organism (PPM) over 1 year. Patients were stratified according to the presence of CBI by any PPM, as well by a single or multiple isolation of PA during follow-up. An adjusted mixed-effects linear regression model was used to investigate the independent effects of CBI and PA isolation on FEV1 decline over time. Results: During follow-up, PPMs were never isolated in 43.3% of patients, in 23.9% of them PPMs were isolated once, and CBI by any PPM was confirmed in 32.8% of participants. FEV1 decline in the entire cohort was 33.7 (95% confidence interval [CI], 21.4-46.1) ml/year. This was significantly increased in patients with CBI by any PPM (57.1 [95% CI, 28.5-79.3] ml/year) and in those in whom PA was isolated at least once (48.5 [95% CI, 27.3-88.2] ml/year). Multivariable analysis showed that the presence of both CBI by any PPM, and at least one PA isolation, were independent factors associated with faster FEV1 decline adjusted by baseline FEV1, presence of bronchiectasis, body mass index, age, exacerbations, smoking status, symptoms, baseline treatment, and comorbidities. Conclusions: The presence of CBI by any PPM, and one or more PA isolation, were independently associated with FEV1 decline in patients with COPD.