Within-subject variability of Mycobacterium tuberculosis-specific gamma interferon responses in German health care workers.
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Within-subject variability of Mycobacterium tuberculosis-specific gamma interferon responses in German health care workers. / Ringshausen, Felix; Nienhaus, Albert; José, Torres Costa; Knoop, Heiko; Schlösser, Stephan; Schultze-Werninghaus, Gerhard; Rohde, Gernot.
in: CLIN VACCINE IMMUNOL, Jahrgang 18, Nr. 7, 7, 2011, S. 1176-1182.Publikationen: SCORING: Beitrag in Fachzeitschrift/Zeitung › SCORING: Zeitschriftenaufsatz › Forschung › Begutachtung
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TY - JOUR
T1 - Within-subject variability of Mycobacterium tuberculosis-specific gamma interferon responses in German health care workers.
AU - Ringshausen, Felix
AU - Nienhaus, Albert
AU - José, Torres Costa
AU - Knoop, Heiko
AU - Schlösser, Stephan
AU - Schultze-Werninghaus, Gerhard
AU - Rohde, Gernot
PY - 2011
Y1 - 2011
N2 - 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.
AB - 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.
KW - Germany
KW - Humans
KW - Reproducibility of Results
KW - Tuberculosis/diagnosis
KW - Health Personnel
KW - Interferon-gamma/analysis
KW - Mass Screening/methods/standards
KW - Mycobacterium tuberculosis
KW - Reagent Kits, Diagnostic/standards
KW - Germany
KW - Humans
KW - Reproducibility of Results
KW - Tuberculosis/diagnosis
KW - Health Personnel
KW - Interferon-gamma/analysis
KW - Mass Screening/methods/standards
KW - Mycobacterium tuberculosis
KW - Reagent Kits, Diagnostic/standards
M3 - SCORING: Journal article
VL - 18
SP - 1176
EP - 1182
IS - 7
M1 - 7
ER -
