Prevalence of latent tuberculosis infection among pregnant women with prediabetes in Kawempe National Referral Hospital, Kampala, Uganda
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Background: Globally, the burden of tuberculosis (TB) among pregnant women is substantial and is associated with poor maternal and neonatal outcomes. Prediabetes, an intermediate hyperglycaemic state coupled with immunological dysregulation in pregnancy favours Mycobacterium tuberculosis infection and progression to active disease. Accurate timing for diagnosis and treatment of latent TB infection (LTBI) is important to reduce morbidity and mortality for both mother and child. Antenatal care (ANC) presents a unique opportunity for evaluation and management of LTBI among individuals with risk of TB who may not otherwise present for medical care. However, there is a paucity of data on the prevalence and factors associated with LTBI among pregnant women with prediabetes, necessitating this study. Objective: To determine the prevalence and factors associated with LTBI among pregnant women with prediabetes. Methods: Between September and November 2020, a cross-sectional study that consecutively enrolled pregnant women, attending ANC clinic at Kawempe National Referral Hospital, Kampala, Uganda was conducted. Participants who had known or suspected active TB based on intensified TB case finding evaluation or who had recently (previous 6 months) received treatment for TB, and those with diabetes mellitus were excluded. A semi-structured questionnaire was administered to study participants to gather demographics and medical history. Prediabetes was defined as glycated haemoglobin (HbA1c) level between 5.7% and 6.4%. LTBI was defined as an interferon- gamma concentration ≥0.35 IU/mL (calculated as either TB1 [eliciting CD4+ T-cell responses] AND/OR TB2 [eliciting both CD4+ and CD8+ Tcell responses] antigens minus Nil) using QuantiFERON TB Gold-Plus (QFT-Plus) assay. Multivariable logistic regression analysis was performed to evaluate factors associated with LTBI among participants with prediabetes. Results: A total of 112 participants, with a median age of 30 (interquartile range (IQR): 24 — 33) years were enrolled. The median gestation age was 26 (IQR: 19 to 31) weeks of amenorrhea. A total of 13 (11.6%) participants had HIV infection. The majority (n=74, 66.1%) of the participants had visible BCG scars, were from urban areas (n=91, 82.0%) and had a crowding index of ≥5 persons/household (n=80, 71.4%). The overall prevalence of LTBI was 44.6% (50/112) (95% confidence interval [95% CI]: 35.2% — 54.3%). TB1 response was positive in 37 (33.0%) participants, TB2 in 45 (40.2%), and 32 (28.6%) were positive for both TB1 and TB2. Factors that were strongly associated with LTBI were as follows; age of ≥30 years (adjusted Odds Ratio (aOR): 2.4, 95% CI: 1.2 — 5.7, p= 0.027), HIV infection (aOR: 4.2, 95% CI: 2.6 — 11.8, p= 0.044), and a crowding index of ≥5 persons per household (aOR: 3.0, 95% CI: 1.4 — 8.3, p= 0.03). No association was found between LTBI and a history of TB contact, BCG vaccination status, residence (rural or urban), alcohol use, or family history of diabetes mellitus (all p> 0.05). Conclusions: The prevalence of LTBI among pregnant women with prediabetes was found to be relatively high at 44.6% compared to the global prevalence of about 25%. There was a statistically significant association between LTBI and HIV-infection, advanced maternal age, and a high crowding index. Recommendations: These findings further support the need for TB preventive therapy among high-risk pregnant women.