In this study, we documented the epidemiology of TB in AI/ANs and NH/PIs in the U.S. during 2003–2008. We found important similarities and differences between these two groups as well as with other racial/ethnic groups in the U.S. Although the absolute numbers of cases among AI/ANs and NH/PIs were smaller than among the other racial/ethnic groups, their case rates exceeded those of non-Hispanic white people. During the five-year study period, the greatest percentage decline in rates was observed for AI/ANs. This finding may be related, in part, to the smaller proportion of patients in this group who were foreign-born compared with other groups; in recent years, TB case rates among the U.S.-born population have been decreasing at a faster pace than those for foreign-born people.18
Conversely, NH/PIs experienced the largest overall percentage increase in rates from 2003 to 2008, due in large part to an increase in cases in 2007. It is important to interpret these changes with caution, however, because of the potential for unstable estimates due to the small number of TB cases in this group. A small change in the number of cases reported in NH/PIs (e.g., due to an individual clinician's diagnostic and practicing patterns) could affect the case rates and trends. Overall, case rates for NH/PIs and AI/ANs are higher than the CDC's 2000 national interim target of 3.5 per 100,000 population.23
These differences in rates of TB constitute important health disparities. Eliminating racial/ethnic health disparities is a goal of several federal initiatives, including Healthy People 2020.24
We found that the proportion of AI/AN TB patients who were homeless, unemployed, or used alcohol excessively was higher than other groups, similar to the findings for 1993–2002.16
Almost one-quarter of AI/AN TB patients were homeless within the past year, which is significantly greater than the proportion found for other racial/ethnic groups. TB already has been recognized as an important health threat for homeless AI/ANs. Almost half of the patients in a TB outbreak among homeless people in Washington State from 2002 to 2003 were AI/AN.25
Early detection and treatment of TB disease among homeless people is a priority for TB prevention and control activities in the U.S.26
Furthermore, we found that a large proportion of TB patients (43%) who were AI/AN included reports of excessive alcohol use within the past year, almost three times that reported for all TB patients ≥15 years of age in the U.S. between 1997 and 2006 (15.1%).27
These findings highlight the importance of TB-control programs to work together with poverty reduction and alcohol abuse programs to simultaneously manage the diseases of addiction and TB and address the underlying causes of disease in AI/ANs.
An important finding in this study was that TB cases among AI/ANs were reported from communities that tended to have fewer resources. Approximately half of the TB cases in AI/ANs were reported from rural communities, which may add to the challenges of TB case detection, management, and contact investigations in AI/ANs due to the distances health-care personnel and patients must travel.16,28
Compared with the counties for other racial/ethnic groups, counties in which AI/ANs resided had the greatest proportion of the population who were living in poverty, unemployed, and without health insurance. Previous studies have found community- and population-level factors (e.g., level of education and socioeconomic status in a community) to be associated with TB risk,29,30
and improvements in population health and health services are related to improvements in TB outcomes.31
Poverty is an important social determinant of disease and a key obstacle to health and health care.32
Promotion of equity and pro-poor policies in TB prevention and control activities, including working to improve the conditions of daily life among AI/ANs in the U.S., is needed.8,29
We found that AI/ANs more commonly received DOT throughout TB treatment than other racial/ethnic groups, despite the barriers to successful DOT present in many AI/AN communities. Similar to a study comparing indigenous groups with the general population in Canada,5
we found AI/AN TB patients had comparable treatment completion rates as other racial/ethnic groups. The DOT patient-centered approach to treatment support is recommended as a core element of TB care and control efforts,33,34
and DOT has been associated with improved TB treatment outcomes.35,36
Access to guaranteed health care and, hence, total DOT through Indian Health Service (IHS), tribal, and urban Indian health-care facilities, may have contributed to the recent declines in case rates among AI/ANs over time. In addition to the ongoing decrease in TB case rates in AI/ANs found in this and previous studies,16
these findings highlight the success of recent TB-control efforts focusing on AI/ANs in the U.S.
We found that NH/PIs were more likely to be female, younger, and diagnosed with extrapulmonary disease. These findings were similar to a previous study using NTSS data comparing Asian/Pacific Islanders with non-Hispanic white people in the U.S. between 1993 and 2006.37
Other studies in the U.S. have found associations between extrapulmonary disease and nonwhite race and/or ethnicity,38,39
region of birth,40
and genotypic lineage.41,42
We also found that, compared with other groups, NH/PIs were more frequently diagnosed clinically and less commonly had HIV infection, a known risk factor for extrapulmonary disease.43
These findings are important for informing TB-control strategies among NH/PI TB patients who lack common risk factors for extrapulmonary disease to ensure disease detection and provision of appropriate TB treatment.
We found that TB cases among NH/PIs are reported from communities in which, on average, there was a greater proportion of people with at least a high school diploma and the lowest unemployment rate. Although TB cases in NH/PIs were reported from communities that tended to have more resources, they may have difficulties in accessing those resources. In a study involving 50 NH/PI TB patients from the Marshall Islands living in Arkansas from 2000 to 2005, 65% of symptomatic TB patients had delayed diagnosis (>60 days from symptom onset), largely owing to patients not seeking medical care, difficulties navigating the health-care system, and language and transportation barriers.44
Furthermore, previous studies have found that individual-level TB risk factors, such as diabetes, are prevalent in NH/PIs45,46
and, thus, may have contributed to the high rates of TB in this population, regardless of the level of community resources. However, because more extensive individual-level data were not available, we were unable to assess this possibility in our study. To reduce health disparities, the recent increases in the TB case rate among NH/PIs found in this study highlight the growing need to better understand the obstacles to and best strategies for TB prevention and control in this group.
For this study, we used self-reported race/ethnicity data based on categories used by the Census Bureau. We recognize that the racial/ethnic minority groups are, in reality, heterogeneous and constitute unique individuals and groups within each broad classification. However, to monitor progress or setbacks in inequalities in health,47
researchers and advocacy groups have been promoting more disaggregated health data to quantify health issues; teach others about disparities; and improve planning, funding, and health-care delivery in underserved communities.48
In this study, the differences found between NH/PIs and AI/ANs highlight the need to develop flexible TB-control strategies tailored to the specific needs of the unique racial/ethnic groups in the U.S. More comprehensive studies can help to more thoroughly understand the epidemiology of TB within the NH/PI and AI/AN groups.
Our study had several limitations. First, there was the potential for misclassification for race/ethnicity. For example, in a study of HIV/acquired immunodeficiency syndrome reporting systems, the authors found racial misclassification of AI/AN was associated with degree of ancestry of AI/ANs and living in an urban setting.49
In this study, race/ethnicity was self-reported, and we restricted our analyses to only those who reported a single race/ethnicity. However, it is unlikely that misclassification introduced a systematic bias, as there is no reason to expect the accuracy of self-reporting of a single race/ethnicity to be different among groups. Any misclassification would most likely have resulted in under-estimating case counts among AI/ANs or NH/PIs. We attempted to further limit the level of misclassification of AI/ANs and NH/PIs by excluding cases originating from countries or territories that did not fit the race/ethnicity definitions.
Second, we only included cases in the NTSS, so our analysis missed any TB cases that were not reported or not registered in the system because of counting criteria. The IHS, which provides health care for approximately 60% of AI/ANs, has an independent system for recording cases of TB and other diseases among inpatients and outpatients. While there are guidelines in place for the IHS to report TB cases to local and state authorities, the extent to which this occurs is not well understood; an evaluation is planned to compare TB cases reported in the NTSS with data on TB cases identified in the IHS system at selected sites.
Finally, we recognize the potential for ecological fallacy when applying the average characteristics at a county level to individuals within that community. It was not possible to tease out the indirect influence of community-level factors in this study, given the complex matrix of other factors such as biology and the population's historical experience with the epidemic that are also in play. While our data were not structured to specifically use statistical methods that allow for the consideration of the hierarchy of factors, this analysis was intended to help inform future studies on community-level factors that may be of importance; these studies should gather data from various sources that will allow for the incorporation of these methods.