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Updated: May 11, 2026
A Tuberculosis Molecular Bacterial Load Assay (TB-MBLA)
Published on: April 30, 2020
Incremental value of T-SPOT.TB for diagnosis of active pulmonary tuberculosis in children in a high-burden setting: a
Daphne I Ling1, Mark P Nicol, Madhukar Pai
1Department of Epidemiology and Biostatistics, McGill University, Montreal, Quebec, Canada.
Insights
T-SPOT.TB testing did not improve tuberculosis diagnosis in children when combined with clinical data and standard tests. This finding is crucial for diagnosing TB infection in pediatric populations, especially in high-burden areas.
Area of Science:
- Pediatric infectious diseases
- Diagnostic test evaluation
- Tuberculosis research
Background:
- Interferon gamma release assays (IGRAs) are increasingly used for tuberculosis (TB) infection.
- The incremental value of IGRAs beyond traditional methods in children with active TB has not been established.
- This study focuses on T-SPOT.TB, a specific IGRA, in a pediatric cohort.
Purpose of the Study:
- To evaluate the added diagnostic value of T-SPOT.TB in smear-negative children with suspected active TB.
- To compare the performance of T-SPOT.TB against patient demographics, clinical signs, and conventional tests.
- To determine if T-SPOT.TB provides incremental benefit in a high-burden setting.
Main Methods:
- A study involving 491 smear-negative children in Cape Town, South Africa.
- Bayesian model averaging to identify key clinical predictors of culture-confirmed TB.
- Statistical analysis including Area Under the Curve (AUC), Net Reclassification Improvement (NRI), and Integrated Discrimination Improvement (IDI) to assess T-SPOT.TB's added value.
Main Results:
- Key predictors for TB included prolonged cough, prolonged fever, night sweats, malaise, household contact history, and HIV status.
- T-SPOT.TB results did not significantly improve diagnostic accuracy when added to clinical predictors, chest radiography, and tuberculin skin test.
- Marginal improvements in AUC (3%), NRI (7%), and IDI (3%) were observed, but confidence intervals often included the null value.
Conclusions:
- In a high-TB-burden setting, T-SPOT.TB testing offers no significant added diagnostic value in smear-negative children when used alongside clinical assessment and conventional tests.
- Clinical signs and symptoms remain critical for TB diagnosis in this population.
- Further research may be needed to identify specific subgroups of children where T-SPOT.TB could be beneficial.
Introduction:
Interferon γ release assays (IGRAs) are increasingly used for tuberculosis (TB) infection, but their incremental value beyond patient demographics, clinical signs and conventional tests for active disease has not been evaluated in children.
Methods:
The incremental value of T-SPOT.TB was assessed in 491 smear-negative children from two hospitals in Cape Town, South Africa. Bayesian model averaging was used to select the optimal set of patient demographics and clinical signs for predicting culture-confirmed TB. The added value of T-SPOT.TB over and above patient characteristics and conventional tests was measured using statistics such as the difference in the area under the receiver operating characteristic curve (AUC), the net reclassification improvement (NRI) and the integrated discrimination improvement (IDI).
Results:
Cough longer than 2 weeks, fever longer than 2 weeks, night sweats, malaise, history of household contact and HIV status were the most important predictors of culture-confirmed TB. Binary T-SPOT.TB results did not have incremental value when added to the baseline model with clinical predictors, chest radiography and the tuberculin skin test. The AUC difference was 3% (95% CI 0% to 7%). Using risk cut-offs of <10%, 10-30% and >30%, the NRI was 7% (95% CI -8% to 31%) but the CI included the null value. The IDI was 3% (95% CI 0% to 11%), meaning that the average predicted probability across all possible cut-offs improved marginally by 3%.
Conclusions:
In a high-burden setting, the T-SPOT.TB did not have added value beyond clinical data and conventional tests for diagnosis of TB disease in smear-negative children.
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