# Lateral-flow urine lipoarabinomannan for TB diagnosis in children

## TL;DR

A urine test for TB in children shows high accuracy in confirming TB cases but needs to be paired with other tests due to low sensitivity.

## Contribution

The study evaluates the AlereLAM test for TB diagnosis in children in a high-burden, resource-limited setting.

## Key findings

- AlereLAM had high specificity (87.9%) and positive predictive value (73.5%) for TB diagnosis in children.
- Sensitivity was low at 21.3%, indicating the test may miss many TB cases.
- Test positivity was higher in confirmed TB cases compared to unconfirmed or unlikely TB cases.

## Abstract

Diagnosing childhood TB is challenging due to nonspecific symptoms and difficulty obtaining sputum samples. This study evaluated the urine-based Alere Determine™ TB-LAM Ag test (AlereLAM) in a high-burden TB, HIV, and malnutrition setting.

Médecins Sans Frontières conducted a cross-sectional study in Malakal, South Sudan (October 2021–November 2023). Children (6 months–15 years) with presumptive TB received clinical and laboratory tests, including Xpert-Ultra and AlereLAM, regardless of HIV status. TB was classified as confirmed (Xpert-Ultra positive), unconfirmed (clinical), or unlikely.

Of the 276 children (median age: 44 months), 53.3% (147/276) were female, 64.9% (179/276) were severely malnourished, and 9.4% (26/276) were children living with HIV. TB was confirmed in 10.5% (29/276), unconfirmed in 50.7% (140/276), and unlikely in 38.8% (169/276). Overall, AlereLAM positivity was 17.8% (49/276), with higher positivity in confirmed TB (27.6%; 8/29) than unconfirmed (20.0%; 28/140) and unlikely TB (12.1%; 13/107). Using confirmed plus unconfirmed TB as positive and unlikely TB as negative reference standard, sensitivity was 21.3% (95% confidence interval [CI]: 15.4–28.3), specificity 87.9% (95% CI: 80.1–93.4), positive predictive value (PPV) 73.5% (95% CI: 58.9–85.1), and negative predictive value 41.4% (95% CI: 34.9–48.1).

AlereLAM’s high specificity and PPV support ruling in TB in resource-limited settings, but low sensitivity highlights the need for additional diagnostic tests.