Change in lung function in never-smokers with nontuberculous mycobacterial lung disease: A retrospective study

Abstract

Purpose: Never-smokers account for a large proportion of subjects in general population studies on nontuberculous mycobacteria lung disease (NTM-LD). However, the influence of NTM infection on the lung function of never-smokers has not yet been evaluated. The aim of this study was to determine how NTM-LD impairs the lung function in never-smokers, and whether there are an association between successful NTM-LD treatment in radiologic outcomes and improvement in lung function of never-smokers with NTM-LD or not. Methods: We performed a retrospective study of patients (1) who have never smoked during their lifetime; (2) with at least two respiratory specimens from sputum, one bronchial washing sample, or one lung tissue that were culture positive for the same NTM species; and (3) who underwent at least two pulmonary function tests. We enrolled healthy never-smokers as the control group. Results: In 22 never-smokers with NTM-LD, the median forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) at baseline was lower than those in 9 healthy never-smokers [1800 vs 2080 ml (p = 0.23) and 2230 vs 2620 ml (p = 0.06)], respectively. The median change in FEV1 in never-smokers with NTM-LD was lower than that in healthy never-smokers [−70 vs 20 ml per year (p = 0.07), respectively]. On univariate analysis, baseline %-predicted FEV1 in never-smokers with NTM-LD was associated with changes in FVC (p = 0.026) and FEV1 (p = 0.013). Anti-NTM treatment was administered for at least 1 year in 19 patients (86.4%). The relationship between worsening chest CT findings and rapid progressive decline in both FVC (p = 0.66) and FEV1 (p = 0.23) were not significant. Conclusion: Never-smokers with NTM-LD showed lung function decline. There was no association between successful NTM-LD treatment in radiologic outcomes and improvement in lung function of never-smokers. Keywords: Lung function, Never-smoker, Nontuberculous mycobacterial lung disease, Bronchiectasis