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