Detection of lipoarabinomannan in urine for identification of active tuberculosis among <scp>HIV</scp>‐positive adults in <scp>E</scp>thiopian health centres

Abstract

Abstract Objective To assess the diagnostic performance of urine lipoarabinomannan ( LAM ) detection for TB screening in HIV ‐positive adults in E thiopia. Methods Testing for LAM was performed using the Determine TB ‐ LAM lateral flow assay on urine samples from participants in a prospective cohort with baseline bacteriological categorisation for active TB in sputum. Characteristics of TB patients with regard to LAM status were determined. Participants were followed for 6 months to evaluate survival, retention in care and incident TB . Results Positive LAM results were found in 78/757 participants. Among 128 subjects with definite (confirmed by culture and/or Xpert MTB / RIF ) TB , 33 were LAM ‐positive (25.8%); the respective figure for clinically diagnosed cases was 2/20 (10%). Five of the remaining 43 LAM ‐positive individuals had died during the 6‐month follow‐up period, whereas 38 remained in care without clinical signs of TB . The overall sensitivity, specificity, positive predictive value ( PPV ) and negative predictive value ( NPV ) were 25.8%, 92.9%, 42.3% and 86.0%, respectively. Among TB patients, LAM positivity was associated with higher WHO clinical stage, lower body mass index ( BMI ), CD 4 cell and haemoglobin levels, and with increased mortality. A combination algorithm of urine LAM testing and sputum smear microscopy detected 49 (38.2%) of definite TB cases; among those with CD 4 count ≤100 cells/mm 3 , this proportion was 66.7%. Conclusions The performance of urine LAM testing for TB detection was poor in this population. However, this was improved among subjects with CD 4 count ≤100 cells/mm 3 . In combination with sputum microscopy urine, LAM could be considered for targeted TB screening in this subgroup.