Trends, Mechanisms, and Racial/Ethnic Differences of Tuberculosis Incidence in the US-Born Population Aged 50 Years or Older in the United States

Abstract

Background: Older age is a risk factor for tuberculosis (TB) in low incidence settings. Using data from the US National TB Surveillance System and American Community Survey, we estimated trends and racial/ethnic differences in TB incidence among US-born cohorts aged ≥50 years.

Methods: In total, 42 000 TB cases among US-born persons ≥50 years were reported during 2001-2019. We used generalized additive regression models to decompose the effects of birth cohort and age on TB incidence rates, stratified by sex and race/ethnicity. Using genotype-based estimates of recent transmission (available 2011-2019), we implemented additional models to decompose incidence trends by estimated recent versus remote infection.

Results: Estimated incidence rates declined with age, for the overall cohort and most sex and race/ethnicity strata. Average annual percentage declines flattened for older individuals, from 8.80% (95% confidence interval [CI] 8.34-9.23) in 51-year-olds to 4.51% (95% CI 3.87-5.14) in 90-year-olds. Controlling for age, incidence rates were lower for more recent birth cohorts, dropping 8.79% (95% CI 6.13-11.26) on average between successive cohort years. Incidence rates were substantially higher for racial/ethnic minorities, and these inequalities persisted across all birth cohorts. Rates from recent infection declined at approximately 10% per year as individuals aged. Rates from remote infection declined more slowly with age, and this annual percentage decline approached zero for the oldest individuals.

Conclusions: TB rates were highest for racial/ethnic minorities and for the earliest birth cohorts and declined with age. For the oldest individuals, annual percentage declines were low, and most cases were attributed to remote infection.

Keywords: age groups; disease progression; health status disparities; latent tuberculosis; race factors.

Figure 1.

Raw and estimated TB incidence rate among US-born individuals aged ≥50 years during 2001–2019. A, Raw TB incidence rate of 5-year birth cohorts. B, Estimated TB incidence rate as a function of age. Abbreviation: TB, tuberculosis.

Figure 2.

Annual percentage decline in TB incidence¹ in the overall cohort and in each sex and race/ethnicity group. A, Annual percentage decline (%) in TB incidence by age in the overall cohort. B, Annual percentage decline (%) in each sex and race/ethnicity group.² Panels were arranged in decreasing order of TB case counts (left to right). Solid line indicates point estimates and shaded region indicates 95% confidence intervals. Rates are based on the incidence observed among US-born individuals aged 50 and over during 2001–2019. Abbreviation: AIAN, American Indian/Alaska Native; NHPI, Native Hawaiian/Pacific Islander; TB, tuberculosis. ¹Analytic model assumes the annual percentage decline is the same for each birth cohort. This assumption is relaxed in the sensitivity analyses. ² Following US Census Bureau conventions, persons reporting Hispanic or Latino origin were categorized as Hispanic; non-Hispanic persons were categorized as Asian, Black, White, American Indian/Alaska Native, Native Hawaiian or other Pacific Islander, based on their reported race.

Figure 3.

Estimated TB incidence rate and the annual percentage decline in TB incidence attributed to remote infection and recent infection. A, Estimated TB incidence rate in TB attributed to remote infection. B, Estimated TB incidence rate in TB attributed to recent infection. C, The annual percentage decline in TB attributed to remote infection. D, The annual percentage decline in TB attributed to recent infection. Solid line indicates point estimates and shaded region indicates 95% confidence intervals. The rates are based on the incidence observed among US-born individuals aged 50 and over during 2011–2019. Abbreviation: TB, tuberculosis.

Figure 4.

Estimated TB incidence rate as a function of birth cohort for the combined cohort and in each sex and race/ethnicity group. A, Estimated TB incidence rate as a function of cohort in the overall cohort. B, TB incidence rate as a function of cohort in each sex and race/ethnicity group,¹ controlling for age (assuming the age of 70). Solid line indicates point estimates and shaded region indicates 95% confidence intervals. Abbreviations: AIAN, American Indian/Alaska Native; NHPI, Native Hawaiian/Pacific Islander; TB, tuberculosis. ¹Following US Census Bureau conventions, persons reporting Hispanic or Latino origin were categorized as Hispanic; non-Hispanic persons were categorized as Asian, Black, White, American Indian/Alaska Native, Native Hawaiian or other Pacific Islander, based on their reported race.

Figure 5.

Estimated incidence rate ratio of each sex and race/ethnicity group to Whites. Panels A–E representing differences in TB burden between each race/ethnicity-sex group¹ relative to Whites. Solid line indicates point estimates and shaded region indicates 95% confidence intervals. Supplementary Tables 3 and 4 report the point estimates for each decade of cohort in each group. Abbreviations: AIAN, American Indian/Alaska Native; NHPI, Native Hawaiian/Pacific Islander; TB, tuberculosis. ¹ Following US Census Bureau conventions, persons reporting Hispanic or Latino origin were categorized as Hispanic; non-Hispanic persons were categorized as Asian, Black, White, American Indian/Alaska Native, Native Hawaiian, or other Pacific Islander, based on their reported race.