Tuberculosis incidence among people aged 50 years or older in the United States is high but declining rapidly within subsequent birth cohorts, according to a study in Clinical Infectious Diseases.
As an example, the researchers noted that “the average 50-year-old in 2001 could expect their annual TB risk to decline by 77% by the time that person turned 68 in 2019.”
“Although we found strong evidence that the annual percentage decline was shallower for older individuals, annual reductions in TB risk were still over 4% in the oldest age group in our sample,” Sun Kim, MS, a doctoral student in population health sciences at the Harvard T.H. Chan School of Public Health, and colleagues wrote.
“Most TB cases in the United States result from reactivation of a latent TB infection (LTBI), with incidence highest in the older population,” Kim told Healio. “While observational cohort studies have shown that the risks of LTBI reactivation decline up to 20 years after infection, there is little empirical evidence on how risks of LTBI progression change for individuals with remote infection.”
According to Kim and colleagues, 42,000 TB cases were reported among U.S. residents aged 50 years or older between 2001 and 2019. For their study, they used modeling “to decompose the effects of birth cohort and age on TB incidence rates, stratified by sex and race/ethnicity.” The study demonstrated that estimated incidence rates declined with age — for the overall cohort and most sex and race/ethnicity strata.
According to the study, the average annual decline in incidence rates flattened for older participants, from 8.8% (95% CI, 8.34-9.23) in 51-year-olds to 4.51% (95% CI, 3.87-5.14) in 90-year-olds. After controlling for age, the researchers found that the incidence rates were lower for more recent birth cohorts and dropped 8.79% (95% CI, 6.13-11.26) on average between successive cohort years.
Additionally, the researchers found that incidence rates were substantially higher for racial or ethnic minorities across all birth cohorts, whereas rates from recent infection declined at approximately 10% per year as individuals aged.
“Ensuring that TB prevention services are designed to meet the needs of vulnerable and high-risk populations will likely increase the impact of prevention services and ameliorate the health impact of the disparities estimated in this analysis,” Kim said.