Screening for Tuberculosis Infection in Spanish Healthcare Workers Comparison of the QuantiFERON-TB Gold In-Tube Test with the Tuberculin Skin Test

Abstract

Few studies have compared both tests in populations with high M. tuberculosis exposure but low BCG vaccination prevalence. Agreement between both tests is high, especially among negative results. Studies are needed to clarify the reasons for disagreement and to establish the best TST and QFT-G test cutoff point.

Concordancia de las pruebas de tuberculina e Interferón gamma en población reclusa

“…Several studies carried out with immigrant population arriving at or living in Barcelona have proven the high prevalence of TB infection within this group, even when there are important differences depending on the country they come from [10][11][12] . The prevalence of TB infection observed in this study by means of both techniques (24% and 26% with TST and IGRAS respectively) implies a moderate-fair concordance between them (kappa=6; CI: 0.4-0.7) and this agreement is similar to the one observed in previous studies with immunocompetent population (kappa=0.59 13 and 0.65 14 ), in transplanted patients (kappa=0.6 15 ), healthcare staff (kappa=0.56) 16 and close to the one observed in children (kappa=0.78 17 ). Nevertheless, it is dissimilar to the studies carried out in HIV infected patients, where low agreement rates have been achieved (kappa=0.37 18 and 0.38 19 ), yet very similar concordances have been observed with immunocompetent population (kappa=0.52-0.6 20 or 0.54 21 ).…”

Utilidad del Quantiferon-TB Gold in Tube® en el cribado de la infección latente tuberculosa en personal sanitario

“…Por último, en nuestro país, Alvarez-León et al 46 , del Servicio Canario de Salud, llevaron a cabo en 2009 un estudio exhaustivo sobre el coste-efectividad de ambas pruebas, encontrando que el precio por caso del QF-G-IT era de 42 eurosD por determinación, y los costes de la PT, de 39 euros por determinación. Las 2 pruebas varían de forma importante en la estructura de costes.…”

IFN-γ release assay versus tuberculin skin test for monitoring TB infection in healthcare workers

“…Among 32 cross-sectional studies from countries with low and intermediate TB incidence, all but one reported a lower prevalence of positive IGRA than positive TST [52]. The difference in Review the prevalence of positive TST and IGRA was not statistically significant in seven studies [25,48,[53][54][55][56][57]. In the other 24 studies, the difference was statistically significant [13,21,23,27,30,46,47,[49][50][51][58][59][60][61][62][63][64][65][66][67][68][69][70].…”

“…Table 1 lists studies with a head-to-head comparison of TST and IGRA results in HCW that allow the display of the concordant and discordant results. The results of 11 studies comprising a total of 3733 HCW are provided [13,22,23,25,27,50,53,55,59,62,67]. Concerning discordant results, the proportion of IGRAnegative/TST-positive discordance is ten-times larger than IGRApositive/TST-negative discordance (29.5 vs 2.7% of all HCW tested).…”

“…However, this problem is of a smaller scale in countries with high prevalence of LTBI in HCW; for example, 16.3, 6.5 and 2.3% of the HCW with a positive IGRA in Georgia, Portugal and Spain, respectively, had a negative TST [13,23,53]. The second study from Spain comprising young, unexposed students found a low prevalence of LTBI and a high proportion of TST-negative healthcare Review students (37.5%) in those with a positive IGRA [55]. Therefore, two-step screening cannot be recommended for a country or a population with a low incidence of TB, while, for a country with a higher incidence of TB, the problem of underestimation seems to be on a scale that might be acceptable.…”