Comparison of Two Interferon-Gamma Release Assays for Pediatric Tuberculosis Infection

Area of Science:

• Pediatric infectious diseases
• Immunology
• Diagnostic test performance

Background:

• Interferon-gamma release assays (IGRAs) are crucial for identifying tuberculosis infection (TBI) to prevent pediatric tuberculosis (TB).
• Limited comparative data exist for the two main IGRAs in US pediatric populations.
• This study addresses the need for comparative performance data of T-SPOT.TB and QuantiFERON-TB Gold In-Tube in children.

Purpose of the Study:

• To compare the performance of T-SPOT.TB and QuantiFERON-TB Gold In-Tube (QFT-GIT) in a large US pediatric cohort.
• To investigate if quantitative results near test cutoffs explain discordance between the two IGRAs.
• To provide data for informed clinical and public health decisions regarding pediatric TBI screening.

Main Methods:

• A US multicenter study identified 3793 children (aged 0-15 years) tested with both T-SPOT.TB and QFT-GIT.
• Results were compared using McNemar's Chi-square tests, stratified by age and testing reason.
• Quantitative results of discordant cases were analyzed to assess proximity to test cutoffs.

Main Results:

• QFT-GIT yielded a higher positivity rate (10.1%) compared to T-SPOT.TB (7.4%) (P < .001).
• This difference was consistent across most age groups and testing indications.
• Discordance was not explained by results near the standard cutoffs for either test.

Conclusions:

• QFT-GIT demonstrated a higher proportion of positive tuberculosis infection test results than T-SPOT.TB in this pediatric cohort.
• The observed discordance between the two IGRAs was not attributable to quantitative results falling close to the diagnostic thresholds.
• Findings highlight differences in IGRA performance in children and suggest further investigation into discordance factors.