A battery-powered near point-of-care TB test detected 85% of culture-positive cases

Design

Cochrane systematic review and diagnostic accuracy meta-analysis

Population

3,291 people with presumptive pulmonary TB in five studies, nine high-burden countries

Primary outcome

Sensitivity and specificity against culture

Effect

Sensitivity 85.4% (82.2–88.1), specificity 97.6% (96.9–98.1); 7.5 points less sensitive than Xpert Ultra

A Cochrane review, supported by the WHO, assessed near point-of-care nucleic acid amplification tests: battery-operated instruments designed to diagnose tuberculosis in peripheral clinics without special infrastructure. Five studies with 3,291 participants in nine high-burden countries met the criteria, all evaluating the same sputum test, the only one meeting WHO's class definition. It was published on 9 October.

Against culture, sensitivity was 85.4% (95% CI 82.2–88.1) and specificity 97.6% (96.9–98.1), moderate-certainty evidence. Compared head to head with Xpert MTB/RIF Ultra, sensitivity was about 7.5 points lower with similar specificity. Compared with smear microscopy, sensitivity was 22 points higher, with slightly lower specificity. Sensitivity fell to 79% in people with HIV and 67% in smear-negative, culture-positive disease. In 1,000 people with symptoms where 100 have TB, the test would miss about 15 and falsely diagnose about 22.

For India, the value lies at the periphery: where the alternative is smear microscopy, this test finds many more cases on the day. Where an established rapid molecular test is available, it is somewhat less sensitive. Most studies ran the test in laboratories, so performance in real peripheral clinics is still to be shown, and data in children are almost absent.

• Consider a near point-of-care NAAT in place of smear microscopy where rapid molecular testing is not otherwise available.
• Prefer Xpert MTB/RIF Ultra or an equivalent where it is accessible, as it was more sensitive.
• Do not use a negative result to exclude TB in people with HIV or smear-negative presentations.
• Confirm positive results according to the national programme algorithm, including drug-resistance testing.

Why it matters

It could bring same-day molecular TB diagnosis to clinics that today rely on a microscope.

Don't overread it

Most studies ran the test in laboratories, so field performance in peripheral clinics is not yet established.

The statistics, in plain English

Sensitivity of 85% means about 15 in 100 people with TB test negative; specificity of 97.6% means about 2 to 3 in 100 without TB test positive. Both matter: missed cases go untreated, and false positives receive six months of unnecessary treatment.

Read the rest in the app

You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.

Get Daily Doctor — free

Scan to keep reading on your phone. No account needed to start.