RESEARCH AND PRACTICE
Disparities in Tuberculosis Burden Among South Asians Living in New York City, 2001–2010 Natalie Stennis, MPH, Lisa Trieu, MPH, Bianca Perri, MPH, Janelle Anderson, MPH, Muhammad Mushtaq, MD, and Shama Ahuja, PhD
At the peak of the New York City (NYC) tuberculosis (TB) epidemic in 1992, there were 3811 cases of TB reported to the NYC Department of Health and Mental Hygiene, resulting in an incidence rate of 51 cases per 100 000 persons.1 Since 1992, the number of TB cases and rate of TB in NYC have steadily declined, falling to 711 reported cases in 2010 (8.7 cases per 100 000 persons).1 However, beginning in 1997, the number of foreign-born TB cases exceeded the number of US-born cases, and this trend has continued. In 2010, 80% of TB cases in NYC were foreignborn.1 Although TB incidence rates have fallen for both groups, declines have been much larger among the US-born, and the difference in incidence rates between the 2 groups remains persistently high. This ongoing disparity suggests a need to better understand TB in foreign-born individuals living in NYC, a city of 8 million people, of whom approximately 40% are foreign-born.2 Previous work has found substantial heterogeneity in the risk of TB among foreignborn people in NYC by country of birth.3 Declining resources for TB control necessitate the identification of meaningful groupings of foreign-born populations to prioritize and target for interventions. The NYC Bureau of Tuberculosis Control (BTBC) has undertaken several projects to better understand and identify high TB burden subpopulations in NYC.3 These efforts have identified South Asians living in NYC as a particular group of interest. In 2010, more than one third of the world’s TB patients lived in South Asia, and 4 of the World Health Organization’s top 22 high TB burden countries are in South Asia.4 In NYC, several South Asian countries were among the top 10 most common countries of birth for foreign-born TB patients from 2001 to 2010. Furthermore, although 7% of all foreign-born residents of NYC originated from South Asia in 2010, this group accounted for 13% of new foreign-born TB patients.5 In this
Objectives. We have described the characteristics of South Asian-born tuberculosis (TB) patients living in New York City (NYC) and compared them with other foreign-born patients to explore possible explanations for the disproportionate burden of TB in the South Asian population. Methods. We used data on demographic and clinical characteristics for TB patients identified by the NYC Bureau of Tuberculosis Control from 2001 to 2010 to compare South Asian patients with other Asian and other foreign-born patients. We reviewed genotyping and cluster investigation data for South Asian patients to assess the extent of genotype clustering and the possibility of local transmission in this population. Results. The observed disparity in TB rates and burden among South Asians was not explained by social or clinical characteristics. A large amount of TB strain diversity was observed among South Asians, and they were less likely than other foreign-born patients to be infected with the same TB strain as another NYC patient. Conclusions. The majority of South Asians were likely infected with TB abroad. South Asians represent a meaningful foreign-born subpopulation for targeted detection and treatment of TB infection in NYC. (Am J Public Health. 2015;105:922–929. doi:10.2105/AJPH.2014.302056)
analysis, we have described the characteristics of South Asian TB patients and compared them with other foreign-born patients living in NYC to explore the disproportionate burden of TB in the South Asian population.
METHODS We included all foreign-born patients in NYC who were verified as having active TB disease from 2001 to 2010. US-born patients included those born in the United States or a US territory; all others with known country of birth were considered foreign-born. Previous work by the BTBC identified a very high burden of TB, including multidrug-resistant TB, in the Tibetan population of NYC, prompting a community needs assessment and tailored interventions.6 We excluded patients known to be of Tibetan origin from this analysis to avoid inflating estimates of South Asian TB incidence and potentially misrepresenting the characteristics of South Asian patients. There is no consistent definition of South Asia in the public health literature. For the purposes of this study, we defined South Asians
922 | Research and Practice | Peer Reviewed | Stennis et al.
based on the World Bank South Asia region, which includes the following countries: Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka.7 We chose the World Bank definition because it was consistent with the definition used in a US national study of TB in South Asians and allowed us to easily identify comparison groups.8 We compared South Asians to 2 other groups: other Asians, which we defined based on the World Bank East Asia and Pacific region (Cambodia, China, East Timor, Fiji, Indonesia, Kiribati, North Korea, Laos, Malaysia, Marshall Islands, Micronesia, Mongolia, Myanmar, Palau, Papua New Guinea, Philippines, Samoa, Solomon Islands, South Korea, Thailand, Tonga, Tuvalu, Vanuatu, and Vietnam), and other foreignborn, which we defined as all other foreignborn patients.7
Descriptive Analysis We extracted data from the BTBC electronic surveillance and case management system. We estimated incidence rates for each group and by South Asian country of birth using
American Journal of Public Health | May 2015, Vol 105, No. 5
RESEARCH AND PRACTICE
denominator data from the US Census Bureau American Community Surveys and Decennial Census, and detected significant trends using the Cochran---Armitage test.9,10 For demographic and clinical characteristics measured as categorical variables, we calculated unadjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) using the Pearson v2 test, excluding the missing values, to compare South Asians with other Asians and other foreignborn individuals. For quantitative data, we compared medians using the Wilcoxon ranksum test. We defined patients with a history of TB infection as those with a self-reported or documented diagnosis of TB infection or disease 12 or more months before the current TB diagnosis. We measured socioeconomic status by neighborhood-level poverty per NYC Department of Health and Mental Hygiene guidelines, using the US Census Bureau data on the percentage of residents within a census tract living below the federal poverty limit.11 Patients were geocoded to their address at diagnosis and assigned to a census tract. We used poverty data from the 2000 Decennial Census for patients verified as having active TB disease before 2005, and we used the American Community Survey 5-year sample poverty data for patients identified from 2005 to 2010. We divided neighborhood-level poverty into 4 categories representing the percentage of neighborhood residents living below the federal poverty limit: low (
Disparities in Tuberculosis Burden Among South Asians Living in New York City, 2001–2010 Natalie Stennis, MPH, Lisa Trieu, MPH, Bianca Perri, MPH, Janelle Anderson, MPH, Muhammad Mushtaq, MD, and Shama Ahuja, PhD
At the peak of the New York City (NYC) tuberculosis (TB) epidemic in 1992, there were 3811 cases of TB reported to the NYC Department of Health and Mental Hygiene, resulting in an incidence rate of 51 cases per 100 000 persons.1 Since 1992, the number of TB cases and rate of TB in NYC have steadily declined, falling to 711 reported cases in 2010 (8.7 cases per 100 000 persons).1 However, beginning in 1997, the number of foreign-born TB cases exceeded the number of US-born cases, and this trend has continued. In 2010, 80% of TB cases in NYC were foreignborn.1 Although TB incidence rates have fallen for both groups, declines have been much larger among the US-born, and the difference in incidence rates between the 2 groups remains persistently high. This ongoing disparity suggests a need to better understand TB in foreign-born individuals living in NYC, a city of 8 million people, of whom approximately 40% are foreign-born.2 Previous work has found substantial heterogeneity in the risk of TB among foreignborn people in NYC by country of birth.3 Declining resources for TB control necessitate the identification of meaningful groupings of foreign-born populations to prioritize and target for interventions. The NYC Bureau of Tuberculosis Control (BTBC) has undertaken several projects to better understand and identify high TB burden subpopulations in NYC.3 These efforts have identified South Asians living in NYC as a particular group of interest. In 2010, more than one third of the world’s TB patients lived in South Asia, and 4 of the World Health Organization’s top 22 high TB burden countries are in South Asia.4 In NYC, several South Asian countries were among the top 10 most common countries of birth for foreign-born TB patients from 2001 to 2010. Furthermore, although 7% of all foreign-born residents of NYC originated from South Asia in 2010, this group accounted for 13% of new foreign-born TB patients.5 In this
Objectives. We have described the characteristics of South Asian-born tuberculosis (TB) patients living in New York City (NYC) and compared them with other foreign-born patients to explore possible explanations for the disproportionate burden of TB in the South Asian population. Methods. We used data on demographic and clinical characteristics for TB patients identified by the NYC Bureau of Tuberculosis Control from 2001 to 2010 to compare South Asian patients with other Asian and other foreign-born patients. We reviewed genotyping and cluster investigation data for South Asian patients to assess the extent of genotype clustering and the possibility of local transmission in this population. Results. The observed disparity in TB rates and burden among South Asians was not explained by social or clinical characteristics. A large amount of TB strain diversity was observed among South Asians, and they were less likely than other foreign-born patients to be infected with the same TB strain as another NYC patient. Conclusions. The majority of South Asians were likely infected with TB abroad. South Asians represent a meaningful foreign-born subpopulation for targeted detection and treatment of TB infection in NYC. (Am J Public Health. 2015;105:922–929. doi:10.2105/AJPH.2014.302056)
analysis, we have described the characteristics of South Asian TB patients and compared them with other foreign-born patients living in NYC to explore the disproportionate burden of TB in the South Asian population.
METHODS We included all foreign-born patients in NYC who were verified as having active TB disease from 2001 to 2010. US-born patients included those born in the United States or a US territory; all others with known country of birth were considered foreign-born. Previous work by the BTBC identified a very high burden of TB, including multidrug-resistant TB, in the Tibetan population of NYC, prompting a community needs assessment and tailored interventions.6 We excluded patients known to be of Tibetan origin from this analysis to avoid inflating estimates of South Asian TB incidence and potentially misrepresenting the characteristics of South Asian patients. There is no consistent definition of South Asia in the public health literature. For the purposes of this study, we defined South Asians
922 | Research and Practice | Peer Reviewed | Stennis et al.
based on the World Bank South Asia region, which includes the following countries: Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka.7 We chose the World Bank definition because it was consistent with the definition used in a US national study of TB in South Asians and allowed us to easily identify comparison groups.8 We compared South Asians to 2 other groups: other Asians, which we defined based on the World Bank East Asia and Pacific region (Cambodia, China, East Timor, Fiji, Indonesia, Kiribati, North Korea, Laos, Malaysia, Marshall Islands, Micronesia, Mongolia, Myanmar, Palau, Papua New Guinea, Philippines, Samoa, Solomon Islands, South Korea, Thailand, Tonga, Tuvalu, Vanuatu, and Vietnam), and other foreignborn, which we defined as all other foreignborn patients.7
Descriptive Analysis We extracted data from the BTBC electronic surveillance and case management system. We estimated incidence rates for each group and by South Asian country of birth using
American Journal of Public Health | May 2015, Vol 105, No. 5
RESEARCH AND PRACTICE
denominator data from the US Census Bureau American Community Surveys and Decennial Census, and detected significant trends using the Cochran---Armitage test.9,10 For demographic and clinical characteristics measured as categorical variables, we calculated unadjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) using the Pearson v2 test, excluding the missing values, to compare South Asians with other Asians and other foreignborn individuals. For quantitative data, we compared medians using the Wilcoxon ranksum test. We defined patients with a history of TB infection as those with a self-reported or documented diagnosis of TB infection or disease 12 or more months before the current TB diagnosis. We measured socioeconomic status by neighborhood-level poverty per NYC Department of Health and Mental Hygiene guidelines, using the US Census Bureau data on the percentage of residents within a census tract living below the federal poverty limit.11 Patients were geocoded to their address at diagnosis and assigned to a census tract. We used poverty data from the 2000 Decennial Census for patients verified as having active TB disease before 2005, and we used the American Community Survey 5-year sample poverty data for patients identified from 2005 to 2010. We divided neighborhood-level poverty into 4 categories representing the percentage of neighborhood residents living below the federal poverty limit: low (
