Impact of Treatment Outcome on Mortality in Mycobacterium abscessus Complex Pulmonary Disease.

BACKGROUND

Mycobacterium abscessus complex (MABC) is a major causative pathogen of nontuberculous mycobacterial pulmonary disease (PD) and is notoriously difficult to treat. However, the impact of culture conversion on survival has not been explored in previous studies. Herein, we investigated the relationship between culture conversion and mortality in patients with MABC-PD.

RESEARCH QUESTION: Is culture conversion associated with mortality in patients with MABC-PD?

STUDY DESIGN AND

METHODS

We conducted a retrospective study analyzing patients with MABC-PD who completed at least 6 months of macrolide-based treatment at a tertiary referral center in South Korea from 2012 to 2023. We assessed the association between culture conversion and all-cause mortality during the follow-up period using extended Cox proportional-hazards models, with culture conversion treated as a time-dependent covariate.

RESULTS

Among the 172 patients, 100 (58.1%) achieved culture conversion at treatment completion, whereas 72 (41.9%) did not. The median follow-up period was 4.4 (interquartile range, 2.5-7.9) and 3.1 (interquartile range, 1.9-4.8) years for patients with and without culture conversion, respectively. The all-cause mortality rate was significantly higher in patients without culture conversion (22.5% vs 6.0%; P = .002). The 5- and 10-year mortality rates were 5.5% and 7.7% among patients who achieved culture conversion, compared with 25.7% and 51.0% among those who did not, respectively. Cox regression analysis revealed a 1.57-fold increased mortality risk in patients without culture conversion (95% CI, 1.13-2.20; P = .008).

INTERPRETATION: This study identifies culture conversion at treatment completion as a key prognostic factor in patients with MABC-PD, with failure to achieve conversion significantly associated with increased mortality. Given the poor treatment outcomes of MABC-PD, novel therapeutic strategies are needed to enhance culture conversion and improve long-term prognosis.