Prevalence of latent tuberculosis infection and risk of infection in patients with chronic kidney disease undergoing hemodialysis in a referral center in Brazil

Objective: To determine the prevalence of latent tuberculosis infection (LTBI) and the risk of infection in patients with chronic kidney disease treated at a hemodialysis center. Methods: We included 307 patients with chronic kidney disease undergoing hemodialysis at the Mineiro -Institute of Nephrology, located in the city of Belo Horizonte, Brazil. All of the patients were submitted to tuberculin skin tests (TSTs). We investigated the booster effect and TST conversion, if the initial TST (TST1) was negative, a second TST (TST2) was performed 1-3 weeks later in order to investigate the booster effect. If TST2 was also negative, a third TST (TST3) was performed one year after TST2 in order to determine whether there was TST conversion. Results: When we adopted a cut-off induration of 5 mm, the prevalence of LTB1 was 22.20/o on TST1, increasing by 11.2% on TST2. When we adopted a cut-off induration of 10 mm, the prevalence of LTB1 was 28.5% on TST1, increasing by 9.4% on TST2. The prevalence of LTB1 increased significantly from TST1 to TST2 (booster effect), as well as from TST2 to TST3 (p <0.01 for both). In our sample, the mean annual risk of infection was 1.19%. Conclusions: in the population studied, the prevalence of LTB1 was high, and the mean annual risk of infection was similar to that reported for the general population of Brazil, which suggests recent infection. Keywords: Tuberculosis; Renal insufficiency, chronic; Tuberculin test.