Rationale: Single-site clinic-based studies suggest an increasing prevalence of pulmonary nontuberculous mycobacteria (NTM) disease, but systematic data are lacking.
Objectives: To describe prevalence and trends for NTM lung disease at four geographically diverse integrated heath care delivery systems in the United States.
Methods: We abstracted mycobacterial culture results from electronic laboratory databases and linked to other datasets containing clinical and demographic information. Possible cases were defined as a single positive NTM pulmonary isolate, and definite cases were defined as two positive sputum cultures, or one positive culture from a bronchoalveolar lavage or lung biopsy. Annual prevalence was calculated using United States census data; average annual prevalence is presented for 2004-2006. Poisson regression models were used to estimate the annual percent change in prevalence.
Measurements and main results: A total of 28,697 samples from 7,940 patients were included in the analysis. Of these, 3,988 (50%) were defined as possible cases, and 1,865 (47%) of these were defined as definite cases. Average annual (2004-2006) site-specific prevalence ranged from 1.4 to 6.6 per 100,000. Prevalence was 1.l- to 1.6-fold higher among women relative to men across sites. The prevalence of NTM lung disease was increasing significantly at the two sites where trends were studied, by 2.6% per year among women and 2.9% per year among men. Among persons aged greater than or equal to 60 years, annual prevalence increased from 19.6 per 100,000 during 1994-1996 to 26.7 per 100,000 during 2004-2006.
Conclusions: The epidemiology of nontuberculous mycobacterial lung disease is changing, with a predominance of women and increasing prevalence at the sites studied.