Lung function decline in non-tuberculous mycobacterial pulmonary disease according to disease severity

BACKGROUND: The severity of non-tuberculous mycobacterial pulmonary disease (NTM-PD) can be classified based on an assessment of the patient´s body mass index, age, presence of cavity, erythrocyte sediment rate and sex (BACES). In this study, changes in lung function according to disease severity were analysed.METHODS: Patients with NTM-PD who underwent at least two lung function tests between 1 January 2011 and 31 December 2021, were classified according to their BACES score into mild (0-1), moderate (2-3) and severe (4-5) groups, and changes in lung function were assessed using BACES scores.RESULTS: A total of 354 patients were divided into three groups: mild (n = 108), moderate (n = 216) and severe (n = 30). As disease severity increased, the decrease in forced expiratory volume in 1 sec (FEV₁), forced vital capacity (FVC) and diffusing capacity for carbon monoxide (DL_CO) was greater: respectively 26.4 mL/year, 31.3 mL/year and 35.7 mL/year in case of FEV₁ (P for trend = 0.002); 18.9 mL/year, 25.5 mL/year and 48.9 mL/year in case of FVC (P for trend = 0.002); and 0.7%/year, 1.3%/year and 2.5%/year for DL_CO (P for trend = 0.023) in the mild, moderate and severe groups.CONCLUSION: The decrease in lung function in NTM-PD was correlated with disease severity.