The Association Between Sputum Culture Conversion and Mortality in Cavitary Mycobacterium avium Complex Pulmonary Disease

Abstract

The association between treatment outcome and the mortality of Mycobacterium avium complex (MAC) pulmonary disease (PD) with cavitary lesions is unclear. Here, we assessed the impact of culture conversion on mortality in patients with cavitary Mycobacterium avium complex pulmonary disease. Is the achievement of sputum culture conversion in MAC-PD with cavitary lesions associated with the prognosis? From 2002 to 2020, 351 patients with cavitary MAC-PD (105 with the fibrocavitary type and 246 with the cavitary nodular bronchiectatic type), who had been treated with a ≥6-month macrolide-containing regimen at a tertiary referral center in South Korea, were retrospectively enrolled in this study. All-cause mortality during the follow-up period was analyzed based on culture-conversion at the time of treatment completion. The cohort had a median treatment duration of 14.7 (interquartile range, IQR: 13.4-16.8) months. Of the 351 patients, 69.8% (245/351) achieved culture conversion, while 30.2% (106/351) did not. The median follow-up was 4.4 years (IQR: 2.3-8.3) in patients with culture conversion and 3.1 years (IQR: 2.1-4.8) in those without. For the patients with and without culture conversion, all-cause mortality was 5.3% vs. 35.8% (P<0.001), and the 5-year cumulative mortality was 20.0% vs. 38.4%, respectively. Cox analysis found that a lack of culture conversion was significantly associated with higher mortality (adjusted hazard ratio: 5.73; 95% confidence interval: 2.86-11.50). Moreover, the 2-year landmark analysis revealed a distinct impact of treatment outcome on mortality. The mortality rate of patients with cavitary MAC-PD who did not achieve culture conversion was significantly higher than that of those with culture conversion.