Epidemiology of Mycobacterial Infections

National Institute Of Allergy And Infectious Diseases

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Abstract

Summary: 1) Related to our research goal of quantifying burden and cost of pulmonary nontuberculous mycobacterial disease, we estimated state-specific case numbers and cost of disease across all age groups in the United States, using available published data on direct costs of medical encounters and prescription drugs. We further projected these estimates to 2014. We estimated a total of 40,135 cases nationally in 2010, with an associated cost of $379 million; 87% inpatient- ($330 million) and 13% outpatient-related ($50 million). Annual state estimates varied from 22 to 5,837 cases ($234k-$52 million); median of 550 cases ($5.3 million). Oceanic and gulf states comprised 70% of PNTM cases. Medical encounters among persons with PNTM aged &#8805;65 ($262 million) were two-fold higher than those aged <65 years ($118 million). Of all costs incurred, medications comprised 76% of PNTM expenditures. Projected 2014 estimates resulted in 84,249 national annual cases ($796 million). For a relatively rare disease, the financial cost of PNTM is substantial, particularly among older adults. Future studies estimating PNTM costs should consider long-term disease dynamics. Better data on disease duration, survival and relapse, and modern prevalence estimates 2) Related to our clinical epidemiologic research goal of identifying predictors of disease progression among persons with PNTM, we analyzed clinical and microbiologic data from a cohort of 180 treatment naive patients undergoing standard macrolide-based therapy for MAC lung disease from Mycobacterium avium (MAC). Microbiologically-based criteria such as sputum culture conversion to negative have traditionally been used to define treatment success for mycobacterial diseases. There are, however, limited data regarding whether nontuberculous mycobacterial sputum culture conversion or semi-quantitative culture analysis correlates with subjective or non-microbiologic objective indices of treatment response. We aimed to determine if a semi-quantitative mycobacterial culture scale correlated with clinical disease status and was predictive of long-term sputum mycobacterial culture conversion to negative in a cohort of nodular/bronchiectatic Mycobacterium avium complex lung disease patients undergoing therapy. Patients were followed at standard frequent intervals with symptomatic, radiographic and microbiologic data collected including semi-quantitative mycobacterial culture analysis. After 12 months of therapy, 148 (82%) patients had sputum conversion to culture negative. Baseline semi-quantitative sputum culture scores did not differ between patients with sputum conversion and those without. The change in sputum culture semi-quantitative score from baseline to month 3 was highly predictive of subsequent sputum long-term conversion status indicative of treatment success, as was improvement in cough, and especially early radiographic improvement. Early semi-quantitative sputum agar plate culture results can be used to predict symptomatic and radiographic improvement as well as long-term sputum culture conversion to negative in this population. Thus, semi-quantitative sputum culture scores can be a useful tool for evaluating new NTM lung disease therapies.