Impact of non-tuberculous mycobacteria on pulmonary function decline in chronic obstructive pulmonary disease

Abstract

Objective: Although chronic obstructive pulmonary disease (COPD) is a common form of structural lung disease associated with pulmonary non-tuberculous mycobacteria (NTM) infection, no longitudinal studies have investigated the role of NTM in COPD disease progression.

Design: From 2000 to 2008, spirometry-confirmed COPD patients with sputum specimens sent for mycobacterial cultures were included. Analysis of clinical, microbiological and pulmonary function data was performed.

Results: The 251 patients were divided into three groups according to the number of NTM isolates: multiple (n = 47), single (n = 63), and no (n = 141) isolates. Mycobacterium avium complex was the most common species in multiple isolates (36.2%) and single isolate (28.6%) groups. Overall, 24.7% of COPD patients had been admitted for exacerbations at least once a year, and patients with multiple and single NTM isolates were more than twice as likely as those with no isolate to experience such exacerbations (38.3% vs. 31.7% vs. 17.0%). After controlling for confounders, patients with multiple NTM isolates had a greater decline in forced expiratory volume in one second than those with single or no isolates (-79.4 ± 32.8 ml vs. -61.6 ± 31.9 ml and -56.2 ± 31.5 ml).

Conclusion: This study suggests that NTM may play a role in disease progression and deterioration of pulmonary function in COPD patients.