Comparative Performance of Urine Lipoarabinomannan and Urine Xpert MTB/RIF Ultra for Diagnosing Tuberculosis in Adult Inpatients With Human Immunodeficiency Virus in East London, South Africa.

BACKGROUND

Urine lateral flow lipoarabinomannan (LF-LAM) is a point-of-care tuberculosis (TB) test for patients with human immunodeficiency virus (HIV). Xpert MTB/RIF Ultra (Ultra) has improved sensitivity on sputum compared with the previous generation of Xpert and may improve diagnostic yield for TB on urine-based testing.

METHODS

We conducted a diagnostic accuracy study in East London, South Africa. Adults with HIV hospitalized with ≥1 W4SS (World Health Organization-recommended 4-symptom screen) or clinical concern for TB were enrolled; TB cultures were performed on blood, sputum, and urine. Unprocessed urine was tested with LF-LAM and Ultra on the pellet of 15 mL centrifuged urine. The primary outcome was sensitivity of urine Ultra compared with LF-LAM, with microbiological TB (positive TB culture or molecular test, excluding urine Ultra) as the reference. Secondary outcomes included specificity and diagnostic yield.

RESULTS

Two hundred thirty-eight participants were enrolled with a median CD4 count of 76 cells/mm3. Microbiological TB was diagnosed in 62 (26%). Using microbiological TB as the reference, sensitivity of LF-LAM and urine Ultra was 45% (95% confidence interval, 32-58) and 70% (95% CI, 57-81; McNemar P = .0013); specificity was 93% (95% CI, 81-99) and 100% (95% CI, 92-100; McNemar P = .25). Diagnostic yields for microbiological TB were 34% for sputum Ultra, 45% for urine LF-LAM, 68 for urine Ultra, and 73% for urine LF-LAM and urine Ultra combined.

CONCLUSIONS

Combined urine-based testing (Ultra + LF-LAM) identified nearly three-quarters of medical inpatients with HIV with microbiological TB. Urine Ultra had significantly improved sensitivity compared with LF-LAM.