Photo Credit: Christoph Burgstedt

Regularly asking about risk factors for tuberculosis, such as birthplace and travel history, may improve testing of those at high risk for latent infection.

“In the United States, more than 80% of active tuberculosis (TB) cases occur due to reactivation of latent tuberculosis infection (LTBI),” Jennifer H. Ku, PhD, MPH, notes. “Thus, domestic TB control is focused on preventing progression of LTBI to active TB. However, we know that there are gaps in LTBI testing and that the current testing recommendations are difficult for physicians to implement.”

A better understanding of current LTBI testing practices is necessary to improve testing practices and precisely target the populations at highest risk, she continues.

For a study published in Clinical Infectious Diseases, Dr. Ku and colleagues examined EHR data collected between January 2008 and December 2019 for adult patients from a single institution with no history of active TB. They analyzed which patient characteristics were associated with the greatest likelihood of testing for LTBI.

Few At-Risk Patients Tested for LTBI

The analysis included more than 3.8 million adults (52% female; mean age 43.5). Of these patients, 706,367 were tested for LTBI, and 60,393 had one or more positive test result (Table).

Of all patients in the analysis, more than 1.2 million met one or more screening criteria for LTBI. However, only 210,025 were tested for LTBI.

“Although LTBI testing is recommended for asymptomatic adults who were born in, resided in, or traveled to (>30 days) a TB-endemic country, testing rates were low in this population despite their high LTBI positivity rates,” Dr. Ku notes.

Information about LTBI risk factors is not routinely gathered or included in EHRs, she continues. As a result, “it is understandable” that these testing criteria are difficult to implement, she continues.

“However, these are the current guidelines, and increasing testing in high-risk individuals who are missed by the current testing practices is a priority,” Dr. Ku says. “In this context, improved documentation of variables such as place of birth and travel history is needed to test high-risk populations more appropriately.”

The researchers also found that patients with HBV or HCV were not more likely to be tested than people in the general population despite having higher positivity rates. Dr. Ku notes that HBV and HCV are not currently part of testing guidelines but should be considered for future guidelines.

Improving Testing to Prevent Active TB

Most TB cases result from reactivation of longstanding LTBI, Dr. Ku continues. As a result, clinicians are missing the opportunity to prevent active TB with appropriate testing and treatment of those at the highest risk.

“Increasing testing in high-risk individuals who are missed by the current testing practices is a priority,” she says. “Further, routine assessment for TB risk factors—which include place of birth and travel history and may be poorly documented in current clinical practice—is needed to more appropriately test high-risk populations. In contrast, we also show that many low-risk individuals continue to be tested at high rates, as testing is typically a requirement for employment or in congregate settings. Additional work is needed to refine guidelines that are feasible to operationalize and more appropriately target populations with highest LTBI risk, as well as to identify strategies to support guideline implementation.”

Dr. Ku and colleagues are currently conducting analyses to generate new guideline recommendations. These recommendations are based on variables seen more often in EHRs and would, therefore, “be more feasible to operationalize and will more appropriately target populations with the highest LTBI risk,” she says.

“Our hope is that improved guidelines, along with best practice strategies to support guideline implementation, can better support testing efforts and improve the health of patients.”