Abstract:
Background. The urine lipoarabinomannan (LAM) antigen test is a tuberculosis (TB) diagnostic test with highest sensitivity in
individuals with advanced human immunodeficiency virus (HIV). Its role in TB diagnostic algorithms for HIV-positive outpatients
remains unclear.
Methods. The AIDS Clinical Trials Group (ACTG) A5274 trial demonstrated that empiric TB therapy did not improve 24-week
survival compared to isoniazid preventive therapy (IPT) in TB screen–negative HIV-positive adults initiating antiretroviral therapy
with CD4 counts <50 cells/μL. Retrospective LAM testing was performed on stored urine obtained at baseline. We determined the
proportion of LAM-positive participants and conducted modified intent-to-treat analysis excluding LAM-positive participants to
determine the effect on 24-week survival, TB incidence, and time to TB using Kaplan-Meier method.
Results. A5274 enrolled 850 participants; 53% were male and the median CD4 count was 18 (interquartile range, 9–32) cells/
μL. Of the 850, 566 (67%) had LAM testing (283 per arm); 28 (5%) were positive (21 [7%] and 7 [2%] in the empiric and IPT arms,
respectively). Of those LAM-positive, 1 participant in each arm died and 5 of 21 and 0 of 7 in empiric and IPT arms, respectively,
developed TB. After excluding these 28 cases, there were 19 and 21 deaths in the empiric and IPT arms, respectively (P = .88). TB
incidence remained higher (4.6% vs 2%, P = .04) and time to TB remained faster in the empiric arm (P = .04).
Conclusions. Among outpatients with advanced HIV who screened negative for TB by clinical symptoms, microscopy, and
Xpert testing, LAM testing identified an additional 5% of individuals with TB. Positive LAM results did not change mortality or TB
incidence.
