Pulmonary Nontuberculous Mycobacteria-Associated Deaths, Ontario, Canada, 2001-2013

Abstract

Survival implications of nontuberculous mycobacterial pulmonary disease (NTM-PD) and NTM pulmonary isolation without disease (NTM-PI) are unclear. To study deaths associated with NTM-PD and NTM-PI and differences in survival between them, we conducted a population-based cohort study of persons with microbiologically defined NTM-PD or NTM-PI diagnosed during 2001-2013 in Ontario, Canada. We used propensity score matching and Cox proportional hazards models to compare survival. Among 9,681 NTM-PD patients and 10,936 NTM-PI patients, 87% and 91%, respectively, were successfully matched with unexposed controls. Both NTM-PD and NTM-PI were associated with higher rates of death for all species combined and for most individual species. Compared with NTM-PI, NTM-PD was associated with higher death rates for all species combined, Mycobacterium avium complex, and M. xenopi. NTM-PD and NTM-PI were significantly associated with death, NTM-PD more so than NTM-PI.

Keywords: Canada; Mycobacterium abscessus; Mycobacterium avium complex; Mycobacterium fortuitum; Mycobacterium kansasii; Mycobacterium xenopi; Ontario; Tuberculosis and other mycobacteria; bacteria; mortality; nontuberculous mycobacteria; survival.

Figure

Kaplan-Meier survival curves for any pulmonary NTM isolation, by species group, Ontario, Canada, 2001–2013. Curve comprises all matched and unmatched patients identified during the study period. There is a statistically significant difference among curves (p<0.001, log-rank) in crude survival comparison, uncontrolled for any other variables. Differences between individual species pairs statistically significant (p<0.00005) for all pairs except Mycobacterium abscessus versus M. fortuitum (p = 0.19), M. abscessus versus Mycobacterium avium complex (p = 0.14), and M. fortuitum versus Mycobacterium avium complex (MAC) (p = 0.50).