Non-tuberculous mycobacterial (NTM) infection as a cause of difficult-to-control asthma: a case control study.
Chest. 2010 Sep 9;
Authors: Fritscher LG, Marras TK, Bradi AC, Fritscher CC, Balter MS, Chapman KR
Abstract BACKGROUND: Symptomatic disease due to nontuberculous mycobacteria (NTM) is known to occur commonly in the presence of structural lung disease, but is not described in association with asthma. METHODS: Case-control nested in a cohort. We identified 22 patients with difficult asthma referred to a tertiary academic referral centre and subsequently found to have infection with NTM. We matched each case with 2 controls (next 2 consecutive patients referred for asthma management). RESULTS: It took on average 2.1 years from the onset of new or worsening symptoms to NTM diagnosis. The most common symptoms were worsening cough (77%), sputum production (40.9%) and frequent exacerbations (31.8%). M. avium complex accounted for 63.6% of the infections, M. xenopi the balance. Cases were older (59.8+8.9 vs. 42.6+18 years; p<0.001) and had more severe airflow obstruction (FEV(1) 57% (40-74) vs. 89.5% (80-97); p<0.001). There was no difference between cases and controls in the proportion using inhaled corticosteroids (ICS), nor the average daily dose at the time of presentation, but cases had used ICS for a longer period (17(6.2-20) vs. 4(0.75-6.0) years; p=0.002). Six subjects with NTM were being treated with daily oral steroids while none of the controls was. Of the 22 cases, 10 were treated with antibiotics for NTM, 7 demonstrating clinical improvement or resolution of the presenting symptoms. CONCLUSIONS: NTM infection can be associated with asthma and should be considered in difficult to treat disease, especially in older individuals, with more severe airflow obstruction and greater exposure to inhaled or systemic corticosteroids.
PMID: 20829338 [PubMed - as supplied by publisher]