Performance and variability of QuantiFERON Gold Plus assay associated with phlebotomy type

Assessing the Diagnostic Performance of New Commercial Interferon-γ Release Assays for Mycobacterium tuberculosis Infection: A Systematic Review and Meta-Analysis

BACKGROUND

We compared 6 new interferon-γ release assays (IGRAs; hereafter index tests: QFT-Plus, QFT-Plus CLIA, QIAreach, Wantai TB-IGRA, Standard E TB-Feron, and T-SPOT.TB/T-Cell Select) with World Health Organization (WHO)-endorsed tests for tuberculosis infection (hereafter reference tests).

METHODS

Data sources (1 January 2007-18 August 2021) were Medline, Embase, Web of Science, Cochrane Database of Systematic Reviews, and manufacturers' data. Cross-sectional and cohort studies comparing the diagnostic performance of index and reference tests were selected. The primary outcomes of interest were the pooled differences in sensitivity and specificity between index and reference tests. The certainty of evidence (CoE) was summarized using the GRADE approach.

RESULTS

Eighty-seven studies were included (44 evaluated the QFT-Plus, 4 QFT-Plus CLIA, 3 QIAreach, 26 TB-IGRA, 10 TB-Feron [1 assessing the QFT-Plus], and 1 T-SPOT.TB/T-Cell Select). Compared to the QFT-GIT, QFT Plus's sensitivity was 0.1 percentage points lower (95% confidence interval [CI], -2.8 to 2.6; CoE: moderate), and its specificity 0.9 percentage points lower (95% CI, -1.0 to -.9; CoE: moderate). Compared to QFT-GIT, TB-IGRA's sensitivity was 3.0 percentage points higher (95% CI, -.2 to 6.2; CoE: very low), and its specificity 2.6 percentage points lower (95% CI, -4.2 to -1.0; CoE: low). Agreement between the QFT-Plus CLIA and QIAreach with QFT-Plus was excellent (pooled κ statistics of 0.86 [95% CI, .78 to .94; CoE: low]; and 0.96 [95% CI, .92 to 1.00; CoE: low], respectively). The pooled κ statistic comparing the TB-Feron and the QFT-Plus or QFT-GIT was 0.85 (95% CI, .79 to .92; CoE: low).

CONCLUSIONS

The QFT-Plus and the TB-IGRA have very similar sensitivity and specificity as WHO-approved IGRAs.

Comparing the Diagnostic Performance of QuantiFERON-TB Gold Plus to Other Tests of Latent Tuberculosis Infection: A Systematic Review and Meta-analysis

BACKGROUND

We conducted a review to compare the sensitivity, specificity, reproducibility, and predictive ability of QuantiFERON-TB Gold Plus (QFT-Plus) with that of QuantiFERON-TB Gold In-Tube (QFT-GIT; QIAGEN, Hilden, Germany) and other latent tuberculosis infection (LTBI) tests.

METHODS

We searched MEDLINE, Embase, Web of Science, and the Cochrane Database of Systematic Reviews from January 2013 through May 2020. We included studies comparing QFT-Plus with at least one other LTBI test. We estimated sensitivity from studies of patients with active tuberculosis, and specificity from studies of healthy individuals with low risk of LTBI. Three independent reviewers evaluated eligibility, extracted data, and assessed risk of bias.

RESULTS

Compared with QFT-GIT, the sensitivity of QFT-Plus in patients with active TB was 1.3% higher (95% confidence interval [CI], -0.3% to 2.9%); in 2 studies of patients with very low probability of LTBI, the specificity was 0.9% lower (95% CI, -2.4% to 0.6%). These differences were not statistically significant. The agreement between QFT-Plus and QFT-GIT was high, with a pooled Cohen's kappa statistic of 0.83 (95% CI, 0.79 to 0.88). The reproducibility of QFT-GIT and QFT-Plus was similarly poor. All participants in the studies to estimate sensitivity were aged ≥15 years, and only 6 were people living with human immunodeficiency virus. We found no studies to assess predictive ability.

CONCLUSIONS

QFT-Plus has diagnostic performance that is very similar to that of QFT-GIT. Further studies are needed to assess the sensitivity of QFT-Plus in immunocompromised patients and younger children before concluding if this new version offers advantages.

Fourth-Generation QuantiFERON-TB Gold Plus: What Is the Evidence?

QuantiFERON-TB Gold Plus (QFT-Plus) is the latest generation of interferon gamma release assays (IGRAs) to receive approval from the U.S. FDA, replacing its predecessor, QuantiFERON-TB Gold In-Tube (QFT-GIT). The novelty of QFT-Plus is that it elicits a response from CD8 T cells, in addition to CD4 T cells, thus collecting a broader response from T-cell subsets than QFT-GIT. It was developed with the aim to improve the detection of latent tuberculosis infection (LTBI), especially among recently exposed contacts, immunocompromised hosts, and young children. In this minireview, we summarize the performance of QFT-Plus compared with that of QFT-GIT among active tuberculosis (TB) patients (a surrogate for LTBI patients), high-risk populations, and low-risk individuals based on recent publications. Studies comparing QFT-Plus to QFT-GIT currently do not support the superior performance of QFT-Plus in individuals with active TB and LTBI. The difference in sensitivity between QFT-Plus and QFT-GIT in active TB patients was not significant in nearly all studies and ranged from -4.0 to 2.0%. Among high-risk groups, the agreement between QFT-Plus and QFT-GIT was 89.9 to 96.0% (kappa coefficient range, 0.80 to 0.91). The specificity in the low-risk population was slightly lower for QFT-Plus than for QFT-GIT, with the difference ranging from -7.4 to 0%. Further studies are needed to accurately evaluate the sensitivity of QFT-Plus in immunocompromised hosts and children. In addition, further evidence is required to validate a modified interpretation of QFT-Plus for the identification of false-positive results in low-risk health care workers.

QuantiFERON TB Gold Plus for the diagnosis of tuberculosis: a systematic review and meta-analysis

Estimated 2017 tuberculosis (TB) incidence is 10 million and mainly depends on the reservoir of individuals with latent TB infection (LTBI). Quantiferon^Ⓡ-TB Gold in-Tube (QFT-GIT) is one of the tests used for LTBI detection. Since 2015 a new version, Quantiferon^Ⓡ-TB Gold Plus (QFT-Plus) is available.

OBJECTIVES

To perform a systematic review and meta-analysis to assess the diagnostic accuracy for TB of QFT-Plus compared to QFT-GIT.

METHODS

PubMed and Scopus were used to detect records related to predefined strings from 2015 to 2018. Full text articles dealing with the sensitivity and/or specificity of the QFT-Plus vs. QFT-GIT for active-TB and LTBI detection were analyzed. Scientific quality and risk of bias were assessed using QADAS-2.

RESULTS

We selected 15 articles. Studies were mainly observational and cross-sectional, performed in 8 countries. Sample size differed in the TB group (27 to 164) compared to LTBI group (29 to 1031). Pooled sensitivity of QFT-Plus for active-TB was 0.94 (0.91 and 0.95 for TB1 and TB2, respectively), whereas pooled specificity for healthy status was 0.96. Pooled sensitivity and specificity for LTBI was 0.91 and 0.95, respectively.

CONCLUSIONS

We show that QFT-Plus is more sensitive compared to QFT-GIT for detecting M. tuberculosis infection, mainly due to TB2 responses.