Sequential strategy for the LTBI screening of newly-arrived immigrants in vulnerable social situations

Introduction: Some studies indicate high prevalences of latent tuberculosis infection (LTBI) in the immigrant population, which is relevant because 5-10% of cases will develop active tuberculosis. The objective of this study is to describe the results of a sequential strategy in the newly-arrived immigrant population for the diagnosis of LTBI using the tuberculin skin test (TST) and IGRAs. Methods: A retrospective descriptive study was carried out with immigrants between 6 and 35 years of age from shelters, referred to an international health unit between July 2013 and June 2016. The TST was performed and when it was >= 5 mm, IGRAs were conducted. LTBI was defined as an IGRA >= 0.35 IU/ml and normal chest X-ray. Results: Of the 184 cases. 138 (75.0%) were men, 23.0 years of age. The most common geographical areas were: 63 (34.2%) from Asia, 42 (22.8%) from Eastern Europe and 41 (22.3%) from sub-Saharan Africa. The TST was >= 10 mm in 79 cases (42.9%). The prevalence of LTBI using the sequential strategy was 33/184 (17.9%). Cohen's Kappa index (between TST >= 10 mm and IGRAs) was 0.226. Conclusion: Basing LTBI screening on the TST alone could give rise to an overestimation. Some studies show that sequential screening would be the most cost-effective; this seems most evident in BCG-vaccinated populations. (C) 2017 Elsevier Espalia, S.L.U. and Sociedad Espanola de Enfermedades Infecciosas y Microbiologia Clinica. All rights reserved.