TB risk by time since U.S. entry among non-U.S.-born residents of Washington State, USA

Abstract

BACKGROUND: Progress towards TB elimination in the United States will require improved detection and treatment of latent TB infection among non-U.S.-born residents who remain at disproportionate risk of TB disease. To inform targeted testing efforts, we evaluated risk of TB disease among non-U.S.-born residents of Washington State, USA, by region of origin and time from U.S. entry.METHODS: We conducted a retrospective cohort study among non-U.S.-born residents diagnosed with TB disease in Washington State from 2005 to 2014, for which country-specific population estimates were also available. The risk of TB disease among non-U.S.-born residents was estimated by time since U.S. entry, World Bank region of origin, and WHO TB incidence category.RESULTS: Risk of TB disease for non-U.S.-born residents was highest within the first year after U.S. entry. Among persons from countries with high TB incidence who had resided in the United States for more than 20 years, risk for TB remained elevated.CONCLUSION: Elevated risk of developing TB disease among individuals not born in the United States persisted long after U.S. entry, particularly among persons originating from certain regions and from high-burden countries. These findings contribute to evidence supporting a refinement of existing screening guidelines.

Figure 1

Poisson model estimates of non-U.S.-born Washington State residents with TB per 100,000 by World Bank Region and time since U.S. entry, 2005–2014. TB rates were highest in the first year after U.S. entry and decreased over time in the United States. TB rates remained elevated (>10/100,000) for at least 10 years after U.S. entry among individuals from SSA, EAP, and South Asian regions.

Figure 2

Poisson model estimates of non-U.S.-born Washington State residents with TB per 100,000 by WHO TB incidence and time since U.S. entry, 2005–2014. Overall, TB incidence after U.S. entry varied among those from countries in <101/100,00 compared to ≥101/100,000 TB incidence categories. For individuals from countries with TB incidence of >101/100,000 persons, TB incidence remained >10/100,000 persons for all categories of time in the United States. Note: The values of TB prevalence among the 10–49.9 and 50–100.9/100,000 were very similar and the lines are overlapping.