Table 1.

Recent studies of the diagnosis of latent M. tuberculosis infection

Ref.	Diagnostic test	Study population	Findings
Gran G, Aßmus J, Dyrhol-Riise AM. Screening for latent tuberculosis in Norwegian health care workers: high frequency of discordant tuberculin skin test positive and interferon-gamma release assay negative results. BMC Public Health 2013;13(1):353	TST and the QuantiFERON TB Gold In-Tube test	387 healthcare workers with possible exposure to TB in Norway History of BCG vaccination reported for 97.9 %	4.7 % had both positive TST and positive QFT-GIT 55.3 % had a positive TST (≥6 mm) and 13.7 % a TST ≥15 mm 3.4 % had a positive QFT-GIT In mostly BCG-vaccinated population: high incidence of discordant TST/QFT-GIT results, with most TST+/QFT-GIT−
Park JS, Lee JS, Kim MY. Monthly follow-ups of interferon-γ release assays among health-care workers in contact with patients with TB. Chest 2012 vol. 142 (6) pp. 1461–1468	QuantiFERON TB Gold In-Tube assays were performed monthly for one year	Forty-nine healthcare workers in South Korea; contacts to patients with active pulmonary TB 91.7 % had BCG scars 40 % rarely wore N95 masks	25 % had baseline positive QFT-GIT tests (>0.35 IU mL−1) 52 % had conversions/reversions when single cut-point of 0.35 IU mL−1 used on monthly testing. 10 % had conversions or reversions to 0.7 IU mL−1 ≥ 2 times during one year Frequent fluctuations around the single cut-point were seen, indicating possible variability of the assay, difficulty processing of the specimens, or varying individual T-cell responses to true TB exposure
Fong KS, Tomford JW, Teixeira L, et al. Challenges of interferon-γ release assay conversions in serial testing of health-care workers in a TB control program. Chest 2012;142(1):55–62	QuantiFERON-TB Gold In-Tube	Retrospective chart review of 7,374 newly hired health care workers receiving QGT-GIT testing for screening at the Cleveland Clinic	6.6 % had positive results, 4.1 % had indeterminate results. 52 HCWs later converted with no known TB exposure (median value was 0.63 IU mL−1). Of those, 10 had repeat QFT-GIT testing; eight had reversion. Single cut-point for positivity on serial testing may lead to conversions/reversions of unclear clinical significance
Diel R, Loddenkemper R, Nienhaus A. Predictive value of interferon-γ release assays and tuberculin skin testing for progression from latent TB infection to disease state: a meta-analysis. Chest 2012;142(1):63–75	TST, “in-house” IGRAs, QuantiFERON-TB Gold In-Tube, and T-SPOT.TB	Meta-analysis of 28 studies evaluating PPV or NPV for progression to active TB. No participant had received preventive therapy.	Overall PPV for progression to TB was 2.7 % for the IGRAs vs. 1.5 % for the TST (p <0.0001). When the high-risk groups were considered in a sub-analysis, the PPV was 6.8 % [95 % CI, 5.6–8.3 %] for the IGRA vs. 2.4 % [95 % CI, 1.9–2.9 %] for the TST (p <0.0001) For high-risk individuals in particular, there was a suggestion of higher PPV for the IGRAs compared with TST
Mancuso JD, Mazurek GH, Tribble D, et al. Discordance among commercially available diagnostics for latent tuberculosis infection. Am J Respir Crit Care Med 2012;185(4):427–34	QuantiFERON-TB Gold In-Tube test, T-SPOT.TB test, TST, and Battey skin test using purified protein derivative from the Battey bacillus	Cross-sectional comparison study of 2,017 low-risk military recruits in South Carolina; simultaneous testing performed (tests listed at left). 1,826 recruits completed all tests	Specificity estimates were 99.3 % for TST, 98.7 % for the T-SPOT.TB, and 98.8 % for the QFT-GIT: no statistical difference Modest agreement was seen between the T-SPOT.TB and the QFT-GIT, kappa statistic=0.39 (95 % CI, 0.24–0.54) 77 % of those with a positive result were positive on only one test
Zwerling A, van den Hof S, Scholten J, Cobelens F, Menzies D, Pai M. Interferon-gamma release assays for tuberculosis screening of healthcare workers: a systematic review. Thorax 2012;67(1):62–70	TST, “in-house” IGRAs, QuantiFERON-TB Gold In-Tube, Quantiferon Gold, and T-SPOT.TB	A systematic review of all IGRA studies in HCWs. 50 studies were included, five in high-TB-incidence areas	24 of 25 studies comparing IGRA to TST had lower prevalence of positive IGRA than positive TST, with BCG vaccination not accounting for all difference Concordance was not strong between TST and IGRAs; k values ranged from 0.05 to 0.56
Rangaka MX, Wilkinson KA, Glynn JR, et al. Predictive value of interferon-γ release assays for incident active tuberculosis: a systematic review and meta-analysis. Lancet Infect Dis 2012;12(1):45–55	“In-house” IGRAs, and QuantiFERON-TB Gold In-Tube, and T-SPOT.TB	A systematic review and meta-analysis assessing ability of IGRAs and TST to predict development of active TB. 15 studies with >26,000 participants, including infants/ children and those with HIV-infection or other co-morbidities. Those who had taken preventive therapy were not excluded	Unadjusted IRR for positive vs. negative IGRA was 2.11 (95 % CI, 1.29–3.46). For TST >10 mm, the unadjusted IRR was 1.60 (95 % CI, 0.94–2.72) Unadjusted IRR for the ELISPOT assays (including T-SPOT.TB) was 2.64 [95 % CI, 1.41–4.93] vs. 1.82 [95 % CI, 1.11–2.97] for whole blood ELISA assays (including QuantiFERON-TB Gold In-Tube), when compared with negative IGRA results