Tuberculosis Among Foreign-Born Persons Diagnosed ≥10 Years After Arrival in the United States, 2010–2015

The majority of tuberculosis (TB) cases in the United States are attributable to reactivation of latent TB infection (LTBI) (1). LTBI refers to the condition when a person is infected with Mycobacterium tuberculosis without signs and symptoms, or radiographic or bacteriologic evidence of TB disease. CDC and the U.S. Preventive Services Task Force (USPSTF) recommend screening populations at increased risk for LTBI, including persons who have lived in congregate settings at high risk and persons who were born in, or are former residents of countries with TB incidence ≥20 cases per 100,000 population (2–4). In 2015, foreign-born persons constituted 66.2% of U.S. TB cases (5). During the past 30 years, screening of persons from countries with high TB rates has focused on overseas screening for immigrants and refugees, and domestic screening for persons who have newly arrived in the United States (6,7). However, since 2007, an increasing number and proportion of foreign-born patients receiving a diagnosis of TB first arrived in the United States ≥10 years before the development and diagnosis of TB disease. To better understand how this group of patients differs from persons who developed TB disease and received a diagnosis <10 years after U.S. arrival, CDC analyzed data for all reported TB cases in the United States since 1993 in the National TB Surveillance System (NTSS). After adjusting for age and other characteristics, foreign-born persons who arrived in the United States ≥10 years before diagnosis were more likely to be residents of a long-term care facility or to have immunocompromising conditions other than human immunodeficiency virus (HIV) infection. These findings support using the existing CDC and USPSTF recommendations for TB screening of persons born in countries with high TB rates regardless of time since arrival in the United States (2,3).

In the NTSS, persons are categorized as foreign-born if they were born outside of the United States, U.S. insular* areas, and the freely associated states^† (except persons born abroad to a U.S. citizen parent). The number of years in the United States is defined as the interval from first entry into the United States to the date the TB patient was first reported to a health department. Persons were classified as having arrived in the United States <10 years or ≥10 years before diagnosis. Persons missing month or year of U.S. entry were excluded from the analysis when comparing the two groups. Persons <10 years of age were also excluded from the comparison analysis because they could not have lived in the United States for ≥10 years. Adjusted odds ratios were calculated using a logistic regression model and backward elimination of variables with statistically insignificant effects (p>0.05) in the model to assess the association between receiving a diagnosis of TB disease ≥10 years after U.S. entry compared with <10 years after U.S. entry and a demographic characteristic or TB risk factor. Age at diagnosis was modeled categorically and divided into 10-year groups.

During 1993–2015, the number and proportion of TB cases among foreign-born persons who were missing month or year of U.S. entry declined from 2,689 (36.3%) to 587 (9.2%), and the number and proportion of TB cases among foreign-born persons who arrived in the United States ≥10 years before diagnosis increased from 1,360 (18.4%) in 1993 to 2,922 (46.0%) in 2015 (Figure). During 2010–2015, 38,345 new cases of TB were reported among foreign-born persons, 34,866 (90.9%) of whom had complete U.S. entry date information. During 2010–2015, among all foreign-born persons with TB disease, the median interval from arrival in the United States to developing TB was 9 years, (interquartile range [IQR] = 2–21 years); the median age at arrival was 29 years (IQR = 21–43 years), and the median age at TB diagnosis was 45 years (IQR = 30–62 years). Among foreign-born persons with TB diagnosed after residing ≥10 years in the United States, the median time spent in the United States before developing TB was 21 years (IQR = 14–31 years) compared with 2 years (IQR = 0–5 years) among persons who resided in the United States <10 years. The median age at arrival for both TB patients who had been in the United States ≥10 years and <10 years before diagnosis was 29 years (IQR = 20–42 years, IQR = 22–44 years, respectively). The median age at TB diagnosis was 56 years (IQR = 43–69 years) for persons with TB diagnosed after ≥10 years in the United States, compared with 33 years (IQR = 25–48 years) for persons with TB diagnosed <10 years in the United States. The top three countries of origin for persons with TB diagnosed ≥10 years after U.S. arrival were Mexico (26.8%), the Philippines (14.0%), and Vietnam (9.2%), whereas the top three countries of origin among persons with diagnoses <10 years after U.S. arrival were Mexico (14.3%), India (10.6%), and the Philippines (10.3%). After adjusting for other factors in the multivariable model, ≥10-year residents were significantly more likely to be aged ≥40 years and to report being of Hispanic ethnicity (Table). Similarly, ≥10-year residents were independently associated with residing in a long-term care facility at diagnosis, reporting excess alcohol use during the year preceding diagnosis, and having a history of a non-HIV–related immunocompromising condition, including diabetes mellitus, end-stage renal disease, tumor necrosis factor-alpha antagonist therapy, or having received an organ transplant (Table). However, ≥10-year residents had lower odds of being a resident of a correctional facility at the time of diagnosis (Table).

Acknowledgments

State, local, and territorial health department personnel; Robert Pratt, Steve Kammerer, C. Kay Smith, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC.

Corresponding author: Clarisse A. Tsang, ctsang@cdc.gov, 404-718-5360.

¹Division of TB Elimination, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC.

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FIGURE. Number of tuberculosis cases diagnosed among foreign-born persons <10 years and ≥10 years after arrival in the United States, 1993–2015

The figure above is a histogram showing the number of tuberculosis cases diagnosed among foreign-born persons <10 years and ≥10 years after arrival in the United States, during 1993–2015.

Abbreviations: AIDS = acquired immunodeficiency syndrome; CI = confidence interval; HIV = human immunodeficiency virus; TNF-α = tumor necrosis factor alpha.
* Multivariable model: other characteristics investigated but not significant (p>0.05) in the univariate analysis included having extrapulmonary site of disease only, previous history of TB, being homeless within previous year, reporting injecting drug use within previous year, and reporting noninjecting drug use within previous year.
^† Odds ratios are for the association between each exposure variable and whether the patient had resided in the United States for ≥10 years or <10 years. Each odds ratio was adjusted for all of the other exposure variables displayed in the table using multivariable logistic regression.
^§ Black, Asian, white and “other” are non-Hispanic. The “other” racial/ethnic category includes non-Hispanic Native Hawaiian and Other Pacific Islander, non-Hispanic American Indian/Alaskan Native, those of unknown race, and those reporting multiple races.
^¶ Persons aged 0–9 years were excluded, because they could not have lived in the United States for ≥10 years.
** For variable definitions, refer to the following: CDC. CDC Tuberculosis Surveillance Data Training Report of Verified Case of Tuberculosis (RVCT) Self-Study Modules Participant Manual. Atlanta, GA: U.S. Department of Health and Human Services, CDC; 2009. https://www.cdc.gov/tb/programs/rvct/default.htm.
^†† Laboratory HIV test was either refused or not offered or result was indeterminate or unknown or HIV status was unknown or missing.
^§§ These data do not include HIV-infected patients, but patients who reported immunosuppression caused by either a medical condition or medication, or immunosuppressive therapy.