Researchers identify risk factors for extrapulmonary TB infection
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Key takeaways:
- The most common site of extrapulmonary TB infection was the pleural cavity.
- Comorbidities associated with extrapulmonary TB include diabetes mellitus, HIV and severe kidney disease.
A large study of veterans with tuberculosis identified factors associated with extrapulmonary TB, including non-Hispanic Black race, all-cause mortality within 90 days of diagnosis, diabetes and HIV status, according to a study.
“Few national studies have focused on determining risk factors for [extrapulmonary TB] in the United States,” Gina Oda, MS, associate director of the Public Health National Program Office at U.S. Department of Veterans Affairs, told Healio. “This is a serious information gap that we are trying to address.”
According to the researchers, as TB has declined nationally over the last 3 decades, the proportion of cases that are extrapulmonary vs. pulmonary has increased — likely because of the HIV/AIDS pandemic, changes in demographics at risk for extrapulmonary disease, and an increase in end-stage kidney diseases, they wrote.
However, they added, the same trend has not emerged among veterans with TB, among whom the proportion of extrapulmonary cases has decreased, potentially because of the Veterans Health Administration’s relative success at linking veterans with HIV to proper care compared with non-VHA health systems, the researchers hypothesized.
“Our study of a large cohort of 7,493 veterans cared for in the Veterans Health Administration allowed us to determine risk factors associated with extrapulmonary TB compared to pulmonary TB, giving health care providers important information to better diagnose and manage TB patients in their care,” Oda said.
For the study, Oda and colleagues assessed veterans diagnosed with laboratory-confirmed TB between 1990 and 2022 through a retrospective cohort study. According to the study, the researchers used multivariable logistic regression to estimate the association of demographic and clinical risk factors such as race, comorbid conditions and infection site, among others, with extrapulmonary TB.
Among the nearly 7,500 veterans with laboratory-confirmed TB, 1,397 (19%) were diagnosed with extrapulmonary TB. The most common site of infection was pleural (31.6%; n = 441), followed by lymphadenitis (14.8%; n = 207). The data showed that compared with veterans aged 70 years and older, those aged 20 to 44 years had a higher risk of lymphadenitis, whereas those aged 20 to 44 and 45 to 54 years were at increased risk of blood or bone marrow TB.
The study also revealed additional factors independently associated with extrapulmonary TB, including non-Hispanic Black race/ethnicity vs. non-Hispanic white race/ethnicity and all-cause mortality within 90 days of a sample testing positive for Mycobacterium. Among comorbidities assessed, the study showed that diabetes, HIV and severe kidney disease were associated with increased risk for extrapulmonary TB infection.
“Based on our findings, health care providers should understand which patient populations are at higher risk for extrapulmonary TB and understand the importance of early diagnosis and treatment to prevent severe illness and death,” Oda concluded.
She and colleagues wrote that health care providers caring for these patient populations should be aware of their increased risk for extrapulmonary TB and educated regarding the importance and challenges of early diagnosis.
“Future research efforts to better understand individual risk and protective factors for [extrapulmonary TB] are needed,” they said.
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