TOPLINE

Among routinely tested patients at an Asian American health center, tuberculosis (TB) test conversion was uncommon, but documented international travel was associated with nearly twofold increase in the odds of conversion.
 

METHODOLOGY

• Researchers retrospectively analyzed 2010-2022 data from a federally qualified health center in the San Francisco Bay Area that serves a largely Asian American population.
• The cohort included 5668 patients with no history of TB infection (94% Asian; 60.2% female; 40% were born in the US), a negative initial result, and at least three annual or biennial tests of the same type (tuberculin skin test [TST] or interferon-gamma release assay [IGRA]).
• A nested case-control study with chart review matched 119 test converters with 338 nonconverters by sex, age, test date, and single-room occupancy history; conditional logistic regression estimated the association with travel outside the United States.
• Converters were linked to the California TB disease registry through 2023 to identify later TB disease.

TAKEAWAY

• Test conversion occurred in 3.0% of routine testers (2.1 per 100 person-years), in 3.2% of those tested with IGRA and 2.9% in participants tested with TST.
• Patients with documented international travel between tests had 95% higher odds of test conversion than those without (adjusted OR, 1.95; 95% CI, 1.07-3.57). Among converters, 20% had documented travel vs 13% of non-converters, mostly to East or Southeast Asian countries. 
• Among 119 converters in the chart-reviewed group, 100 received a latent TB infection diagnosis, 57% began treatment, and 65% completed it.
• Two routinely tested patients developed TB disease within 5 years of estimated infection, as did eight of 632 converters overall; all four with available quantitative interferon-gamma release assay values had high-positive results.

IN PRACTICE

"Our results suggest that clinically significant IGRA conversions in low-TB-prevalence countries are rare and that international travel may increase the risk of TB test conversion," the authors wrote. Prospective future studies could "strengthen the argument for incorporating travel into risk-based testing, particularly for those who travel frequently to home countries."

SOURCE

The study was led by Nozomi Fukui, MPH, California Department of Public Health, Richmond, California. It was published online on October 9 in Open Forum Infectious Diseases.

LIMITATIONS

The limitations included the retrospective design, uncertainty over whether travel prompted repeat testing, and non-uniform documentation of testing reasons. Trip duration was recorded for only 41% of travelers, employment type was not routinely collected, treatment completion data were sparse, and small numbers made TB disease estimates unstable.

DISCLOSURES

The authors reported no funding support or conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.