Diagnosis of Latent Tuberculosis Infection: Comparison between the Tuberculin Test and Quantiferon-TB Gold Plus in Household Contacts from the City of Buenos Aires

ARMITANO RITA; MUÑOZ LUIS; SALOMONE CESAR; AMIANO NICOLÁS; TATEOSIAN NANCY; STUPKA JUAN; GALLEGO CLAUDIO; JOZA CARLA; POROPAT ALEJANDRA; GARCÍA VERÓNICA

Revista Americana de Medicina Respiratoria

RAMR

Lugar: Ciudad Autónoma de Buenos Aires; Año: 2019 vol. 19 p. 309 - 312

1852-236X

The epidemiological control strategy of tuberculosis (TB) includes both the diagnosis and early treatment of baciliferous patients andthe identification of individuals with latent tuberculosis infection (LTBI), who represent the pathogen reservoir within the population.Objective: To compare the results obtained using the tuberculin test (PPD, Purified Protein Derivative) and the QuantiFERON-TB GoldPlus (QTF) in a group of household contacts of patients with bacillary pulmonary TB in the city of Buenos Aires. We used two cutoffpoints to consider PPD as positive: ≥ 5 mm (PPD-5) and ≥ 10 mm (PPD-10).Materials and Methods: Blood samples for QTF were taken from household contacts of patients with bacillary TB, followed immediatelyby the application of PPD. The QTF was considered as the reference test from which to compare the PPD by calculatingsensitivity (S), specificity (E), positive predictive value (PPV), negative predictive value (NPV) and Kappa correlation coefficient.Results: 48 contacts were included (33 women, 69%), age 38.8 ± 19 years, 27 (56%) Argentinean, 18 (38%) Bolivians and 3 (6%)Peruvians, 37 were cases of TB. Only one contact informed She/she hadn?t received the BCG; and 44 subjects showed the BCG scar.The QTF was positive in 23 individuals (47.9%) and undetermined in 2 cases (4.2%). Excluding the indeterminate cases from theanalysis, there were no significant differences between positive and negative QTF contacts regarding age (33.8 ± 16 vs. 42.1 ± 20years), nationality: Argentinean (12 of 26.46%) vs. foreigners (11 of 20.55%) and sex: women (18 of 32, 56%) vs. men (5 of 14, 36%).There were 28 (60.9%) positive cases with PPD-5 and 13 (28.3%) with PPD-10. Comparison between PPD-5 vs. PPD-10: S = 73.9 vs.34.8%, E = 52.2 vs. 78.3%, PPV = 60.1 vs. 61.5% and NPV = 66.7 vs. 54.5%. The coincident results (positive and negative) betweenQTF and PPD were 29 (63%) for PPD-5 and 26 (56.5%) for PPD-10. Expressed with the Kappa coefficient, they show weak (0.261)and insignificant (0.130) concordance, respectively.Conclusions: Considering the QTF as the reference method for its higher specificity, PPD-5, although less specific, was more sensitivethan PPD-10 for the diagnosis of latent tuberculosis infection in the group of household contacts under study.