Birth region may predict time to TB diagnosis among foreign-born people in US
Researchers found an association between region of birth and time to diagnosis among foreign-born people in the U.S. with tuberculosis, suggesting that where a person was born may predict progression from latent TB to TB disease, they said.
Previous research has demonstrated that around 70% of incident TB cases in the U.S. occur among individuals who were not born in the U.S, and that more than 85% of U.S. TB cases in persons not born in the U.S. happen when latent TB progresses to TB.
“The CDC recommends that efforts to eliminate TB in the United States focus, in part, on detecting and treating latent TB infection among non-U.S.-born persons,” Amish Talwar, MD, MPH, a medical officer for the CDC, told Healio. “Understanding birth region as a prognostic indicator and other factors associated with progression of latent TB infection to TB disease can guide public health authorities in concentrating TB prevention resources on non-U.S.-born persons with latent TB infection who are at greatest risk for developing TB disease.”
Talwar and colleagues used national TB surveillance data to examine a person’s time from entering the U.S. to TB diagnosis among non-U.S.-born persons who developed TB between 2011 and 2018. They excluded individuals with TB that was attributed to recent transmission, and instead focused on people whose TB was likely caused by progression of latent TB that was acquired in their country of birth.
They found that 46.6% of the TB cases in non-U.S.-born persons were diagnosed 10 years or longer after their arrival in the U.S. The median time to diagnosis was lowest among people from Middle Africa (26 months) and highest among people from Western Europe (524 months). Overall, it was 128 months in men (95% CI, 116-146) and 121 months in women (95% CI, 108-136).
Talwar said the study’s limitations included that the characteristics of U.S. immigrants may not be representative of those who remain in their birth country, an inability to account for the number of non-U.S.-born persons emigrating, an inability to account for the reason for immigration and an inability to categorize the individual countries analyzed.
Other limitations included the potential for misclassification of patients excluded for having TB disease attributable to recent TB transmission, an inability to assess the influence of HIV status and diabetes on date of TB disease diagnosis, and the study not accounting for the population of non-U.S.-born persons who did not develop TB during the course of the study.
“Additional studies using data sources that include information on risk factors like HIV infection and diabetes mellitus would be helpful to determine the potential influence of these comorbid conditions on the progression of latent TB infection to TB disease,” Talwar said. “Such studies would also benefit from accounting for TB rates in birth countries where feasible. Similar studies in countries with health care systems that are comparable to the United States and diverse populations would also help determine if these results are reproducible and could shed light on the causes of regional differences in time to TB disease diagnosis.”