There are few data regarding the impact of nontuberculous mycobacterial lung disease (NTM-LD) on lung function during the clinical course of disease. This study aimed to assess the impact of NTM-LD on lung function decline.
Treatment outcomes and spirometry data at diagnosis and at least three years later were obtained from 358 patients who were diagnosed as NTM-LD between January 1999 and November 2011 using the prospective NTM registry cohort. For analysis, patients were divided into three groups: observed without treatment, treatment success, and treatment failure.
The treatment failure group (n = 68) had a significantly more rapid decline in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) compared with the observation (n = 118) and treatment success (n = 172) groups (–52.2, –30.8, and –28.2 mL/yr, respectively, P = .023 for FEV1 decline; –50.4, –28.8, and –26.0 mL/yr, respectively, P = .002 for FVC decline). After adjusting for confounding factors, patients with treatment failure had greater FEV1 and FVC declines than those observed without treatment (adjusted P = .026 for FEV1 decline; adjusted P = .022 for FVC decline) or treated successfully (adjusted P = .004 for FEV1 decline; adjusted P = .002 for FVC decline). Patients treated successfully had similar declines in FEV1 and FVC to those in the observation group.
The change of lung function was variable over a median 5-year follow-up period. Treatment failure was associated with a substantial decline in lung function in NTM-LD.