Diagnostic accuracy of a rapid urine lipoarabinomannan test for tuberculosis in HIV-infected adults.

ABSTRACT

OBJECTIVE: In settings of high HIV prevalence, tuberculosis control and patient management are hindered by lack of accurate, rapid tuberculosis diagnostic tests that can be performed at point-of-care. The Determine TB LAM Ag (TB LAM) test is a lateral flow immunochromatographic test for detection of mycobacterial lipoarabinomannan (LAM) in urine. Our objective was to determine sensitivity and specificity of the TB LAM test for tuberculosis diagnosis. DESIGN: Prospective diagnostic accuracy study. SETTING: Hospital and outpatient settings in Uganda and South Africa. PARTICIPANTS: HIV-infected adults with tuberculosis symptoms and/or signs. METHODS: Participants provided a fresh urine specimen for TB LAM testing, blood for mycobacterial culture, and 2 respiratory specimens for smear microscopy and mycobacterial culture. MAIN OUTCOME MEASURES: For the TB LAM test, sensitivity in participants with culture-positive tuberculosis and specificity in participants without tuberculosis. RESULTS: A total of 1013 participants were enrolled. Among culture-positive tuberculosis patients, the TB LAM test identified 136/367 (37.1%) overall and 116/196 (59.2%) in the group with CD4 ≤100 cells per cubic millimeter. The test was specific in 559/573 (97.6%) patients without tuberculosis. Sensitivity of the urine TB LAM test plus sputum smear microscopy was 197/367 (53.7%) overall and 133/196 (67.9%) among those with CD4 ≤100. CD4 ≤50 [adjusted odds ratio (AOR), 6.2; P < 0.001] or 51-100 (AOR, 7.1; P < 0.001), mycobacteremia (AOR, 6.1; P < 0.01) and hospitalization (AOR, 2.6; P = 0.03) were independently associated with a positive TB LAM test. CONCLUSIONS: In HIV-positive adults with CD4 ≤100, the TB LAM urine test detected over half of culture-positive tuberculosis patients, in <30 minutes and without the need for equipment or reagents.