Abstract
LAM would be useful in a broader population than in the one currently recommended, and can be expanded for use in HIV-positive ambulatory symptomatic patients less severely immunocompromised and in HIV positive hospitalized patients irrespective of their symptoms.
BACKGROUND
Tuberculosis (TB) is the major killer in HIV-positive patients, but remains difficult to diagnose. The lipoarabinomannan assay (LAM) is a urine based point-of-care test that has shown utility in immunosuppressed HIV-positive patients. Current international guidelines recommend LAM in ambulatory or hospitalized patients with TB symptoms and, CD4<100 cells/µL or seriously ill. We aimed to assess the diagnostic value of LAM in a broader group of patients.
METHODS
A prospective observational study conducted in 6 health facilities in Malawi and Mozambique included 4 groups of HIV-positive patients. All patients had a clinical exam and LAM, chest X-ray, sputum microscopy, and Xpert MTB/RIF assay (Xpert) requested. Culture in sputum was done for a subset of patients. The diagnostic yield was defined as the proportion of patients with a positive assay result among those with laboratory-confirmed TB.
RESULTS
Among 456 ambulatory patients with TB symptoms and CD4<200 cells/µL (group 1), LAM results were available in 99.6%, compared to 77.0% with Xpert results. LAM could diagnose 82.4% of the patients with laboratory confirmed TB (Table). Among 485 ambulatory patients with TB symptoms irrespective of their CD4 (group 2), LAM could diagnose 77.9% of the patients with TB. Of the 360 HIV-positive ambulatory patients with CD4<100 cells/µL irrespective of their symptoms (group 3), 11.9% (43/360) were LAM-positive overall, and 6.6% (13/198) among those with no TB symptoms. Among 387 hospitalized patients irrespective of their symptoms
and CD4 count (group 4), 25.8% (100/387) were LAM-positive overall, and 19.4% (26/134) among those categorized as “no TB suspects”.
CONCLUSION
Expanded use of LAM would be useful in HIV-positive ambulatory patients with TB symptoms and CD4<200 cells/µL, in hospitalized
patients regardless of symptoms and, possibly in symptomatic patients with no CD4 result. In ambulatory patients with very low CD4 count coming for initial or regular HIV-consultation, systematic LAM along with symptom screening may also have value for identifying TB.
