Serial testing with the interferon-γ release assay in Portuguese healthcare workers

Costa, José Torres; Silva, R.; Sá, Raul; Cardoso, Maria João; Nienhaus, Albert

doi:10.1007/s00420-010-0571-x

Cited by 44 publications

(22 citation statements)

References 20 publications

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“…In so far our study corroborates the observations of other studies [23-25]. A high reversion rate of positive IGRA was reported by other studies before [26-33]. As no active TB cases were observed in our study, information for the clinical interpretation of a reversion in IGRA cannot be derived from our data.…”

Section: Discussionsupporting

confidence: 92%

Tuberculosis screening at the Sainte-Anne Hospital in Paris – results of first and second IGRA

Nienhaus

Gariepy

Trouve

et al. 2014

Journal of Occupational Medicine and Toxicology

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IntroductionHealthcare workers (HCWs) are exposed to Mycobacterium tuberculosis (MTB) and therefore are screened for tuberculosis (TB). Results of TB screenings with the Interferon-γ Release Assay (IGRA) in a French psychiatric hospital without a TB ward are described.MethodsAt the Sainte-Anne Hospital, a referral centre for psychiatric patients throughout the municipal region of Paris, IGRA screening is performed during pre-employment and general health examination or after potential contact to MTB. The QuantiFERON Gold in tube (QFT) is used and data on TB history are assessed in a standardized manner.ResultsBetween August 2008 und August 2013 in total 1.192 HCWs were tested and the QFT was positive in 265 (22.2%). Probability of a positive QFT increased with age. A second QFT was performed in 144 HCWs with a positive QFT and 53 (36.8%) HCWs had a reversion. With a positive QFT close to the cut-off (e.g. 0.35-0.7 IU/ml) the odds ratio for a reversion was 4.6 compared to an INF-γ concentration of ≥3.0 IU/ml. Probability of reversion was not influenced by preventive chemotherapy, which was completed by 28 (19.4%) HCWs with a positive QFT. No active TB was detected.ConclusionPrevalence of positive IGRA is high in French HCWs as is the number of reversions in IGRA. Reversion rate is particularly high around the cut-off of the IGRA. A borderline zone will therefore reduce the influence of test variability.

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Section: Discussionsupporting

confidence: 92%

Tuberculosis screening at the Sainte-Anne Hospital in Paris – results of first and second IGRA

Nienhaus

Gariepy

Trouve

et al. 2014

Journal of Occupational Medicine and Toxicology

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“…In addition we identified three studies on cost-effectiveness of IGRAs in HCWs and three studies on feasibility and test implementation. Finally, two new serial testing studies were identified by 1 October 2010, giving a total of 50 studies of IGRAs in HCWs 20 21. The characteristics of the cross-sectional and serial testing studies identified in this review are shown in tables 1 and 2, respectively.…”

Section: Resultsmentioning

confidence: 99%

Interferon-gamma release assays for tuberculosis screening of healthcare workers: a systematic review

Zwerling

Hof²,

Scholten³

et al. 2011

Thorax

221

195

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Healthcare workers (HCWs) are at increased risk of exposure to tuberculosis (TB). Traditionally, screening for latent TB infection (LTBI) is done using the tuberculin skin test (TST). Interferon-gamma release assays (IGRAs) are now increasingly being used for diagnosis of LTBI, but their role in HCW screening is unclear. A systematic review was conducted of all IGRA studies in HCWs to summarise their performance in cross-sectional and serial testing settings. By searching four electronic databases and other sources, all available studies using any one of the commercial IGRA assays in HCWs were retrieved and screened. 50 unique studies were identified which met the inclusion criteria including five from high TB incidence settings. Among 24 cross-sectional studies in low TB incidence settings, the pooled prevalence of positive IGRA using either test was significantly lower than for a positive TST. However, in high-incidence settings (n¼2) there were no consistent differences in the prevalence of positive tests. IGRAs showed good correlation with occupational risk factors for TB exposure in low-incidence settings. Only 10 studies assessed use of IGRA for serial testing and all showed large variation in the rates of conversions and reversions, with no data suggesting that IGRAs are better at identifying the incidence of new TB infection than the TST. The use of IGRAs instead of TST for one-time screening may result in a lower prevalence of positive tests and fewer HCWs who require LTBI treatment, particularly in low TB incidence settings. However, the use of IGRAs for serial testing is complicated by lack of data on optimum cut-offs for serial testing and unclear interpretation and prognosis of conversions and reversions. Further longitudinal research will be required to inform guidelines on serial testing using IGRAs.

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“…The extent of within-subject variability that we determined approximates the proposed borderline zones. Three recent serial testing studies among German and Portuguese HCWs demonstrated that the implementation of a QFT borderline zone of 0.2 to 0.7 IU/ml may safely reduce the rate of inconsistent results (26,29,31). For the T-SPOT, evidence for the safety of a specific borderline zone is sparse.…”

Section: Discussionmentioning

confidence: 99%

Within-Subject Variability of Mycobacterium tuberculosis-Specific Gamma Interferon Responses in German Health Care Workers

Ringshausen

Nienhaus

Costa

et al. 2011

Clin. Vaccine Immunol.

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Gamma interferon (IFN-␥) release assays (IGRAs) are used increasingly for the periodic tuberculosis (TB) screening of health care workers (HCWs), although data regarding the reproducibility and interpretation of serial testing results in countries with a low incidence of TB are scarce. The present study evaluated and compared the within-subject variability of dichotomous and continuous results of two commercial IGRAs, the QuantiFERON-TB Gold In-Tube (QFT) and the T-SPOT.TB (T-SPOT), in German HCWs during a 4-week period. Thirty-five immunocompetent HCWs with low or medium TB screening risk and without known recent TB exposure or tuberculin skin test application were tested repeatedly with both IGRAs at weekly intervals. A total of 158 valid results were obtained for each IGRA. Changes of about ؎70% (QFT) and ؎60% (T-SPOT) from the mean IFN-␥ response accounted for 95% of the within-subject variability. However, according to the manufacturers' cutoffs, inconsistent results were observed more frequently for the QFT (28.6%; four conversions, six reversions) than for the T-SPOT (8.6%; three reversions; P < 0.001). The overall agreement between the IGRAs was good. Regression toward the means accounted for a significant decline in mean IFN-␥ responses of about 25% between successive visits for both IGRAs. Although both assays were highly reliable and reproducible, we observed substantial within-subject variability and regression toward the means during a 4-week period, which should be considered when interpreting serial testing results in comparable populations and settings. Our data support the use of borderline zones for the interpretation of serial IGRA results and the retesting of borderline positive results before offering preventive chemotherapy.

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Serial testing with the interferon-γ release assay in Portuguese healthcare workers

Cited by 44 publications

References 20 publications

Tuberculosis screening at the Sainte-Anne Hospital in Paris – results of first and second IGRA

Tuberculosis screening at the Sainte-Anne Hospital in Paris – results of first and second IGRA

Interferon-gamma release assays for tuberculosis screening of healthcare workers: a systematic review

Within-Subject Variability of Mycobacterium tuberculosis-Specific Gamma Interferon Responses in German Health Care Workers

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