Certain methodological limitations of the study must be considered. Several important factors that have been suggested as risk factors for TB mortality, such as homelessness, history of incarceration, injection drug use, multidrug-resistant TB, compliance with DOT, and delay in diagnosis, could not be ascertained directly by this administrative database. Specifically, missed diagnosis and delayed treatment after hospitalization have been shown to occur more often in hospitals with low TB hospital admission rates and were strongly associated with in-hospital death in Canada. The measure of income was an ecologic rather than patient-specific measure, which can lead to the misclassification of income status. Given that persons with TB tend to have relatively lower socioeconomic status (SES) than their demographic or geographic counterparts, assigning SES values to individuals based on geographic means may actually overestimate their income and, in turn, underestimate the association between SES and TB outcomes. In addition, the results of this study rely on the accuracy of the diagnosis codes. The NIS database does not include patient identifiers, thus validation of the accuracy of the hospital discharge records was not feasible. However, several stud-ies have successfully assessed patient outcomes using the NIS database.
Despite these limitations, the results of this study have major implications for public health programs, health-care providers, and patients. While curative therapy is seemingly readily available in the United States, TB hospitalization rates and the burden on the US health-care system remain substantial. Additionally, the risk of mortality once patients with TB are hospitalized is high and is unlikely to be explained by the HIV epidemic. Patients with older age and a greater number of comorbid illnesses, and patients admitted to the hospital through the emergency department have the highest risk of death. This underscores the importance of the need for improved clinical management strategies that are targeted for high-risk populations, including older patients and those with comorbid disease. comments Furthermore, it highlights the importance of intensifying public health efforts that are aimed at screening and detecting cases, decreasing barriers to seeking care, and increasing public awareness of the importance of TB and receiving early treatment. Much progress has been made in decreasing the prevalence of TB in the United States, but the disease is far from being eliminated, and larger strides are needed to decrease the suffering of those affected.