QuantiFERON-TB Gold Plus evaluation for latent tuberculosis infection among Italian healthcare workers: a cross-sectional study

Abstract


 Background: healthcare workers (HCWs) are at higher risk of being exposed to tuberculosis (TB). The aim of this study was to estimate LTBI prevalence and evaluate associated risk factors among Italian HCWs using a new generation IGRA test, Quantiferon Plus (QTF-Plus), providing also an analytical evaluation of this test.
 Methods: this cross-sectional study was conducted during the annual health surveillance program performed in 2017, evaluating 1470 HCWs of a teaching hospital in Rome, tested with QTF-Plus. A standardized questionnaire was collected for multivariate risk analysis. The independent variables associated with a higher frequency of LTBI were tested in a multivariate logistic regression model.
 Results: LTBI was diagnosed in 50 out of 1470 (3.4%) of HCWs. The male gender and age>40 years were significantly associated with the risk of LTBI. The levels of interferon-γ were significantly lower in subjects with a recent conversion than in those with an older positivity. Moreover, interferon-γ values exceeding 8 IU/ml were recorded in 8 out of 35 remote subjects but in no recent subjects. The concordance between TB1 and TB2 results was 88%, while in 6 out of 50 subjects we found a discrepancy.
 Conclusion: the LTBI condition among Italian HCWs was very low. In subjects with discordant outcomes between TB1 and TB2, especially when the test values are close to the cut-off, is recommended a repetition of the test to confirm its positivity.
 Key words: tuberculosis, latent tuberculosis infection, interferon-gamma release assay, quantiferon plus, healthcare workers

Right to Occupational Safety: Prevalence of Latent Tuberculosis Infection in Healthcare Workers. A 1-Year Retrospective Survey Carried out at Hospital of Lecce (Italy)

“…With regard to primary prevention of LTBI through vaccination, no evidence was found about the protective role of BCG vaccination, given that no significant differences were found among HCWs BCG vaccinated compared to unvaccinated. Our finding is in agreement with other studies [10,12,24] conducted among HCWs working in countries with low incidence of TB.…”

“…In our study the prevalence of LTBI among HCWs was lower compared to data of other studies performed in healthcare settings in low TB incidence countries [1,13,18] and consistent with the findings of Coppeta et al [10,12]. HCWs aged ≥ 40 years were found at higher risk of LTBI; consistently with this finding and with the review performed by da Silva et al [21], an increased OR for LTBI was found in HCWs with length of service ≥ 15 years compared to low-experienced HCWs.…”

“…It is also important to highlight that the findings of our study corroborate the evidence of low LTBI prevalence among HCWs working in Italian hospital settings, showed by recent studies [10,12].…”

“…It is estimated that 23% of world's population and 13.7 of European population have LTBI; in Italy, the incidence rate of TB in the general population is 7.2/100,000 (according to the Italian Institute of Health), but the prevalence of LTBI among the general population has not been established yet [11,12]. To date, there is a lack of information also about LTBI prevalence among HCWs, because of the poor number of studies focused on HCWs and the different diagnostic methods adopted for the diagnosis in a population which was frequently vaccinated with BCG (Calmette-Guerin Bacillus) in the past [13].…”