Epidemiologic trends and mortality in nontuberculous mycobacterial lung disease: a nationwide cohort study in Taiwan (2011-2020).

Background: Nontuberculous mycobacterial lung disease (NTM-LD), a condition characterised by a heterogeneous course and complex multidrug treatment, is becoming an increasingly prevalent global health concern. Given that population-based data on real-world management and outcomes are limited, we aimed to characterise nationwide trends in treatment initiation, real-world treatment courses, and cause-specific mortality among patients treated for NTM-LD, as well as identify factors associated with three-year mortality. Methods: In this retrospective cohort study, we identified patients in Taiwan's National Health Insurance Research Database who had been newly diagnosed with NTM-LD between July 2011 and December 2020 based on diagnostic ICD codes. All identified cases served as the numerator for incidence estimation; the treated NTM-LD cohort comprised patients initiating a multidrug anti-NTM regimen sustained for at least 28 days. The primary outcome was three-year all-cause mortality, ascertained through the national death registry. We used multivariable Cox proportional hazards regression to estimate adjusted hazard ratios and 95% confidence intervals for mortality risk factors. Results: Among 15,589 patients diagnosed with NTM-LD, 3,762 received anti-NTM treatment and comprised the treated NTM-LD cohort. The incidence of NTM-LD increased from 5.4 to 8.9 per 100,000 person-years between 2012 and 2019. The median treatment duration was 158 days. The three-year mortality rate was 19.4%, with cancer, chronic airway diseases, and pneumonia being the leading causes of death. Being aged ≥65 years; male; having chronic respiratory failure, cancer, heart failure, chronic obstructive pulmonary disease, or idiopathic pulmonary fibrosis; being hospitalised (the strongest factor, adjusted hazard ratio = 3.70), and receiving intravenous antibiotic treatment were independently associated with three-year mortality. Conclusions: Our findings point to an increasing burden of treated NTM-LD in Taiwan and a substantial three-year mortality rate. Older age and multiple comorbidities were independently associated with mortality. These findings should be interpreted with caution because cases were defined without microbiologic or radiographic confirmation, and untreated individuals were excluded.