Impact of Bronchiectasis on Treatment Outcomes in Patients With Nontuberculous Mycobacterial Pulmonary Disease: A 10-Year Retrospective Cohort Study Stratified by Bronchiectasis Severity.

BACKGROUND

Bronchiectasis is the most common comorbidity in patients with nontuberculous mycobacterial pulmonary disease (NTM-PD); however, its influence on treatment outcomes remains insufficiently explored.

RESEARCH QUESTION: How does the presence and severity of bronchiectasis affect treatment outcomes in patients with NTM-PD?

STUDY DESIGN AND

METHODS

In this 2-phase retrospective cohort study, a historical cohort of 1,587 patients with NTM-PD and a contemporary cohort of 1,095 patients with NTM-PD were included. The Bronchiectasis Severity Index was used for severity assessment and stratification of bronchiectasis. Treatment success rates, culture conversion rates, time to culture conversion, and risk of treatment failure were compared within each cohort among patients with NTM-PD without bronchiectasis and those with mild, moderate, or severe bronchiectasis.

RESULTS

In both the historical and contemporary cohorts, overall treatment success rates in patients with NTM-PD declined significantly as bronchiectasis severity increased (all P < .001). Similarly, overall culture conversion rates decreased significantly, and time to sputum culture conversion was markedly prolonged (log-rank test, all P < .001). Among patients with Mycobacterium abscessus pulmonary disease, Mycobacterium intracellulare pulmonary disease, and Mycobacterium avium pulmonary disease, moderate and severe bronchiectasis were independent risk factors for treatment failure (all P < .05). For Mycobacterium kansasii pulmonary disease, only severe bronchiectasis was a significant risk factor (both cohorts, P < .05).

INTERPRETATION: Our results show that comorbid bronchiectasis adversely affected treatment outcomes in patients with NTM-PD, with progressively worse outcomes observed as its severity increased. The magnitude of this impact varied across different nontuberculous mycobacteria species, highlighting the need for pathogen- and severity-stratified management strategies.