NEEMA Funded Projects by Topic Area – Tuberculosis
NEEMA 2.0 (2019-2024)
Trends in TB incidence among the elderly are of programmatic and scientific interest. Many of the older US population have had greater exposure to TB infection and have higher prevalence of latent TB infection (LTBI) than younger populations. TB incidence rates are also known to be higher in the elderly. It has been hypothesized that the risks of progression to TB from prior LTBI increase with older age, due either to immunosenescence or to incidence of known medical risks, such as diabetes or cancer, later in life. Only a small percentage of TB cases in older cohorts are thought to be due to recent infection. This analysis will investigate trends in TB incidence and reactivation of LTBI among US-born persons aged 50 years and older in the United States. Specifically, the analysis will describe how TB incidence rates within the older cohort changed from 1993 to 2018, and how trends in earlier birth cohorts compare with those of later birth cohorts.
While TB transmission rates have declined nationally in the United States during the last two decades – owing largely to TB control efforts – responding to TB outbreaks (which often occur among people experiencing homelessness or incarceration) to prevent further transmission, remains an important priority for TB control. Previous studies developed separate models of TB transmission for the four most populous states, California, Florida, New York, and Texas. For each TB outbreak, CDC has data on epidemiologic links and on links based on whole genome sequencing (WGS), which can be leveraged to inform outbreak response by TB programs. This project will focus on large outbreaks (≥10 clustered cases over a 3-year period). The goal of this project is to estimate the epidemiological impact and cost-effectiveness of TB outbreak response in the US. The primary outcomes are the estimated number of TB cases averted with (i) current levels of outbreak response (compared with no outbreak response); and (ii) improved outbreak response, in which data from WGS are incorporated into outbreak response.
Greater than 80% of TB cases in the United States result from reactivation of LTBI. For this reason, identifying and treating individuals with LTBI is a primary focus of TB prevention. Evidence suggests that LTBI reactivation rates vary by age and time since infection, as well as the presence of risk factors associated with minor (e.g., smoking, diabetes, under-nutrition) or major (e.g., advanced HIV, end-stage renal disease) immune suppression. Estimates of current and future LTBI reactivation rates among populations are critical inputs for cost-effectiveness analyses of LTBI testing and treatment, as these rates determine the cumulative TB risk that can be averted by this intervention. Reactivation rates are also important inputs for analyses investigating the current status and future course of population-level TB epidemiology. Despite their importance, reactivation rate estimates for different population groups are either unavailable or are relatively uncertain. This analysis will use a Bayesian evidence synthesis to estimate the distribution of likely reactivation rates for key populations at increased risk for TB. Furthermore, these rates will be projected to estimate cumulative lifetime reactivation risks.
Information on the costs and health outcomes of TB services, such as testing and treatment for LTBI to prevent TB progression, is important for national, state, and local TB decision-making. Knowing the potential epidemiologic and economic impact of TB services, including across populations at risk, allows agencies to allocate resources to maximize health impact and to target interventions across risk populations. Locally tailored evidence on the short- and long-term costs of TB and LTBI, as well as interventions to address these conditions, would also help local areas communicate to local officials, media, and community members the importance of TB prevention and the funding required to effectively address the burden of TB and LTBI. This work will extend the functionality of the existing user-friendly tool, Tabby2external icon, by providing locally tailored results for all 50 states and the District of Columbia and by broadening the functionality of the tool to report future costs and cost-savings associated with TB and TB interventions.