The Impact of Body Mass Index on Latent Tuberculosis Infection: Combined Assessment in People Living with HIV

Background: Tuberculosis (TB) is a leading cause of death among people living with HIV (PLHIV). While body mass index (BMI) affects TB risk, its association with latent tuberculosis infection (LTBI) in PLHIV is unclear. High-transmission settings, such as prisons, may further increase LTBI risk, yet this relationship has not been studied across both prison and community populations of PLHIV. Methods: We conducted a dual cross-sectional study of PLHIV in Jiangsu Province, China, recruiting participants from a prison hospital in 2021 and community healthcare facilities from July to November 2023. BMI was calculated from measured height and weight. LTBI was identified by a positive ESAT6-CFP10 (EC) skin test or the QuantiFERON-TB Gold In-Tube (QFT-GIT) assay. Logistic regression and generalized additive models (GAMs) assessed the association between BMI and LTBI, adjusting for demographic, clinical, and behavioral confounders. Results: A total of 1799 PLHIV were included in the analysis, of whom 343 (19.07%) were recruited from prison settings and 1456 (80.93%) from community-based screening. The overall prevalence of LTBI was 13.79% (n = 248). Obesity (BMI &ge: 28 kg/m2) was linked to a significantly lower risk of LTBI (adjusted OR = 0.47, 95% CI: 0.23&ndash:0.95, p = 0.036), particularly when identified by EC testing (adjusted OR = 0.13, 95% CI: 0.03&ndash:0.54, p = 0.005). The BMI&ndash:LTBI association followed a nonlinear &ldquo:U-shaped&rdquo: pattern, with the lowest prevalence in individuals who were obese. Among those with CD4+ T cell counts &lt: 500 cells/&mu:L, the inverse association between obesity and LTBI was even more marked (adjusted OR = 0.20, 95% CI: 0.05&ndash:0.83, p = 0.027). Conclusion: In summary, obesity is significantly associated with a lower risk of LTBI among PLHIV, with an approximate 54% risk reduction. This inverse relationship was most pronounced when using the EC skin test.