Mortality after Respiratory Isolation of Nontuberculous Mycobacteria. A Comparison of Patients Who Did and Did Not Meet Disease Criteria.

RATIONALE: The mortality of patients with respiratory tract isolates of nontuberculous mycobacteria (NTM) and their risk factors for death are not well described.

OBJECTIVES: To determine age-adjusted mortality rates for patients with respiratory NTM isolates and their causes of death and to examine whether American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) diagnostic criteria identify those at higher risk of death after NTM isolation.

METHODS: We linked vital records registries with a previously identified Oregon population-based cohort of patients with NTM respiratory isolation. We excluded patients with Mycobacterium gordonae (n = 33) and those who died (n = 21) at the time of first isolation. We calculated 5-year age-adjusted mortality rates. We used Kaplan-Meier and Cox proportional hazards analysis to examine the association of ATS/IDSA criteria and other risk factors with death.

RESULTS: Of 368 subjects with respiratory NTM isolates in 2005-2006, 316 were included in the survival analysis. Most (84%) of their cultures isolated Mycobacterium avium complex. 35.1% died in the 5 years following respiratory isolation. Five-year age-adjusted mortality rates were slightly higher for those meeting (28.7/1,000) versus not meeting (23.4/1,000) ATS/IDSA criteria. In multivariate analysis, older age (adjusted hazard ratio [aHR], 1.06; 95% confidence interval [CI], 1.04-1.07) and lung cancer (aHR, 2.77; 95% CI, 1.51-5.07) were associated with an increased risk of death. A trend was noted between meeting ATS/IDSA criteria and subsequent death (aHR, 1.37; 95% CI, 0.95-1.97). Among cases, male sex, older age, and immunosuppressive therapy use were independent risk factors for death.

CONCLUSIONS: In the State of Oregon, patients with NTM respiratory isolates have high mortality, regardless of whether they meet ATS/IDSA criteria for pulmonary NTM disease. Most patients die as a result of causes other than NTM infection.