Many Americans With Latent Tuberculosis Go Untreated

By Linda Carroll

April 18, 2022

NEW YORK (Reuters Health) - Less than half of individuals diagnosed with latent tuberculosis initiate therapy, U.S. data show.

An analysis of data from 15 health department clinics across the country revealed that just 42% of people with latent infection started therapy, with a considerable number of those not completing treatment, researchers report in Clinical Infectious Diseases.

"While significant progress has been made in shortening the duration of latent TB treatment, the largest gap and barrier to successful therapy is at the level of treatment initiation," said study coauthor Dr. Maunank Shah of the Johns Hopkins School of Medicine and the Johns Hopkins Bloomberg School of Public Health, in Baltimore, Maryland.

"Further research is needed to better understand patient knowledge and acceptance of latent TB diagnosis and treatment, and factors impacting retention in care," he told Reuters Health by email.

"About 4-5% of U.S. residents are living with latent TB infection, primarily persons born in or spending significant time in countries with high rates of TB," Dr. Shah noted. "More than three-quarters (80%) of TB cases that develop annually in the U.S. are due to long-standing untreated latent TB infection."

To take a closer look at gaps in the care of latent TB infection (LTBI), Dr. Shah and his colleagues conducted an observational cohort study through the Tuberculosis Epidemiologic Studies Consortium (TBESC), which is a partnership between the Centers for Disease Control and Prevention (CDC), local TB programs and academic institutions. The researchers analyzed six months of clinical data routinely collected between 2016 and 2017 on all patients tested or treated for LTBI.

Included in the analysis were more than 23,000 patients tested by local health departments (median age, 35; 46% male). Most were foreign-born, with a median of 35% of patients at each site being U.S.-born. Among those reporting being foreign-born, the most common countries of origin were the Philippines (18%), Cuba (9%), Syria (7%) the Democratic Republic of the Congo (7%) and Mexico (4%).

For their analysis, the researchers considered all non-U.S.-born patients to have an indication for testing. Among U.S.-born patients, the most common reasons for testing were homeless-shelter screening, drug-rehabilitation screening, contact investigations and medical risks such as HIV and immunosuppression.

Of the 2,515 patients diagnosed with LTBI, 1,073 (42%) initiated therapy; among those, 817 (76%) completed treatment.

"TB elimination in the U.S. will require scaling up TB preventative services in the form of diagnosis and treatment of latent TB infection," Dr. Shah said. "There are currently significant gaps along the LTBI care cascade. Despite existing recommendations, many individuals with latent TB infection remain undiagnosed. And even after diagnosis, the majority do not get started or complete treatment."

The U.S. has one of the lowest rates of TB in the world, said Dr. Andrea Howard, an associate professor of epidemiology at the Columbia University Mailman School of Public Health, in New York City, who was not involved in the research.

"However nearly 7,900 people in the U.S. were diagnosed with TB last year, which is still too many," Dr. Howard told Reuters Health by email. "An estimated 13 million people in the U.S. have a latent TB infection, and if left untreated, about 10% of them will develop TB disease. Detecting and treating latent TB infection to prevent progression to TB disease - along with identifying and treating TB disease to prevent transmission - are required to achieve TB elimination in the U.S."

"We need to understand the barriers that people face in initiating and completing LTBI treatment, so that health departments can design LTBI services that meet people's needs," Dr. Howard said.

SOURCE: Clinical Infectious Diseases, online April 1, 2022.