Comparison of the interferon-gamma release assay with the traditional methods for detecting Mycobacterium tuberculosis infection in children

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.

TB or not TB? Diagnostic difficulties in HIV-positive versus HIV-negative tuberculosis patients with an immigration background in Germany

Patients immigrated or born to immigrated parents constitute an increasing proportion of TB in Germany. This study aimed to assess the clinical presentation and outcome of immigrated TB-monoinfected (TB/HIV–) patients versus TB patients with an HIV coinfection (TB/HIV+). Ninety-three patients (36 boys/men, 57 girls/women; age range, 2–59 years) were investigated of whom 47 were TB/HIV+ and 46 TB/HIV–. TB/HIV+ patients more frequently had an African background (76.6% [36/47], P <0.001), TB/HIV– patients (63.0% [29/46]) more often had an East-European or Asian background ( P <0.001). Most common symptoms included lymphadenopathy (37.6% [35/93]) and weight loss (35.5% [33/93]). In TB/HIV+ patients acute presentation was more frequent including fever (57.4% [27/47]), gastrointestinal (44.7% [21/47]), and respiratory symptoms (36.2% [17/47]). TB skin test was highly positive in all performed cases (20/20), IGRA was positive in 98.2% (55/56) cases applied. Pulmonary involvement was relatively rare (51/93 [54.8%]), especially in TB/HIV– patients (36.10% [17/46]) vs. TB/HIV+ (70.23% [36/47]; P <0.001). An infectious etiology was suspected in only 43.5% (20/46) TB/HIV– vs. 72.3% (34/47) TB/HIV+ patients ( P ⩽0.005); a malignancy was suspected in (21/46 [45.7%] TB/HIV– patients vs. 12/47 [25.5%] TB/HIV+; P ⩽0.043). The diagnostic delay between first presentation to a doctor and TB diagnosis was long in all cases, especially in TB/HIV– patients (range, 0–336 weeks; median, 8 weeks vs. TB/HIV+ patients; range, 0–288 weeks; median, 0 weeks; P <0.05). TB, especially in young immigrated HIV– patients frequently presents as an atypic extrapulmonary disease, which may end up in a delayed diagnosis of up to several years.