LAUSR

Background The prevalence of latent Tuberculosis Infection (LTBI) increases with aging. Interferon gamma release assay (IGRA) is a T-cell based assay, widely used for the detection of LTBI. Objectives To identify the prevalence of LTBI among elderly Greek population using IGRA and to evaluate comorbidities associated with LTBI. Methods Patients equal to or more 65 years, non- immunocompromised without history of active tuberculosis infection, underwent IGRA to identify LTBI. We compared characteristics of participants between the group with LTBI and non-LTBI. Levels of interferon-gamma (INFγ) produced in each group were also analyzed. Results We enrolled 130 (38.7%) patients with LTBI and 206 (61.3%) patients without LTBI. Multivariate logistic regression analysis identified the follow features that were associated independently with positive IGRA: female gender (odds ration- OR: 0.45; 95% CI: 0.28-0.72; p=0.001), chronic heart failure (OR: 0.41; 95% CI: 0.22-0.77; p=0.005), history of major surgery (OR: 0.55; 95% CI: 0.33-0.92; p=0.022) and Charlson' s Comorbidity Index more than 3 (OR: 3.06; 95% CI: 1.46-6.40; p=0.003). Production of stimulated INFγ was significantly lower in the group of non-LTBI. Conclusions Female gender, history of chronic heart failure and history of any surgical intervention are independently associated with negative IGRA result, while CCI more than 3 is associated with positive IGRA. Our results suggest careful interpretation of IGRA among elderly with these characteristics.