Many at-risk patients miss latent TB testing and treatment

Tuberculosis (TB) was the leading infectious cause of death worldwide in 2023, and in the United States most TB disease arises when latent TB infection (LTBI) reactivates. Because LTBI treatment is about 90% effective at preventing active TB, public health efforts focus on screening and treating people with LTBI to move toward elimination. Laura A. Vonnahme and colleagues working with the Tuberculosis Epidemiologic Studies Consortium-III (TBESC-III) set out to measure, in real-world primary care settings, how well patients move through the sequence of care steps often called the LTBI care cascade: who is at higher risk, who gets tested, who is diagnosed, and who starts and completes treatment. The team used patient-level electronic health record (EHR) data from primary care clinics that each serve at least 10,000 non–US-born individuals annually from countries with high TB incidence (defined here as ≥10 cases per 100,000 persons among expatriates living in the US). Higher-risk people were defined as those born outside the US or, when country of birth was unknown, those who preferred a non-English language. The study included anyone in these clinics with a visit during the study period.

This was a longitudinal study using EHR data to follow people through the LTBI cascade. Of 3.5 million people who sought care across participating clinics, an average of 48% were identified as higher risk for TB infection; of those, 69% were considered cascade eligible because they had no prior TB or LTBI testing, diagnosis, or treatment documented. Percentages reported are averages across four sites representing multiple clinics. Among cascade-eligible individuals, only 14% were tested for TB infection. Of those tested, 92% had results available and 17% of test results were positive. For people with positive test results, 82% had chest imaging ordered and 70% met LTBI diagnostic criteria. Among those diagnosed with LTBI, 61% were prescribed treatment; of those prescribed treatment, 87% started therapy and 56% completed it. These steps highlight where patients were lost in the process from risk identification to treatment completion.

The numbers make clear two linked problems: many people at higher risk never get tested, and many of those who are diagnosed do not complete preventive therapy. Even though 17% of tested individuals had evidence of TB infection, an average of 86% of higher-risk people were not tested, leaving a large pool who could benefit from preventive treatment. Among those diagnosed, an average of 39% were not prescribed treatment and nearly half (an average of 44%) did not complete treatment after starting. Because LTBI treatment prevents most cases of active TB, these gaps limit the ability of clinics and health departments to reduce TB disease and related harm. The authors point to targeted interventions to increase LTBI testing among higher-risk patients and to improve treatment initiation and completion as practical steps that could yield more preventive treatment and help reduce TB-associated morbidity in the US.