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

Abstract

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