Abstract
BackgroundWHO guidelines recommend the lateral flow urine lipoarabinomannan assay (LF-LAM) for TB diagnosis in hospitalised HIV-positive individuals. The role of LF-LAM among ambulant patients remains less well defined. We investigated the sensitivity of LF-LAM among ambulant HIV-positive adults in primary health clinics in South Africa.MethodsWe enrolled adults (aged ≥18 y) with CD4 counts of ≤150 cells/mm3 who had not received TB treatment or antiretroviral therapy in the preceding 3 or 6 mo, respectively. Research nurses performed the LF-LAM test on freshly voided urine. Results were compared with a reference standard of positive mycobacterial culture (sputum or urine).ResultsOf 1505 (54.5% female; median age 37 y; median CD4 count 73 cells/mm3) participants, 973 (64.7%) had a mycobacterial culture result; 105/973 (10.8%) were positive for Mycobacterium tuberculosis. LF-LAM sensitivity was 41.9% (95% CI 32.3 to 51.9%) and 19.0% (95% CI 12.0 to 27.9%) using grade 1+ and grade 2+ cut-off points, respectively. Sensitivity increased with severe immunosuppression and in the presence of poor prognostic indicators (low haemoglobin, body mass index).ConclusionsWhen used as the only TB diagnostic test, LF-LAM sensitivity is suboptimal, particularly using the grade 2+ cut-off. More sensitive tests for TB are needed that can be used in primary care settings.
Highlights
TB remains the leading cause of death among HIV-positive people in low- and middle-income counties (LMIC).[1]
We report on a subanalysis of the TB Fast Track trial[6] assessing the sensitivity of lateral flow urine lipoarabinomannan assay (LF-LAM) among ambulant, HIV-positive adults recruited to the intervention arm of the study
The main exclusion criteria were: any TB treatment in the preceding 3 mo; antiretroviral therapy (ART) in the preceding 6 mo; or too sick to be managed in ambulant care
Summary
TB remains the leading cause of death among HIV-positive people in low- and middle-income counties (LMIC).[1]. In January 2014, the manufacturer changed the reference card supplied with the assay from the original five intensity bands to four intensity bands, thereby dropping the grade 1+ cut-off point on the original reference card so that a positive result is represented by the old grade 2+ cut-off only. The effect of this meant that a very low concentration of LAM on the test strip would be interpreted as a negative test result rather than a positive result. Sensitivity increased with severe immunosuppression and in the presence of poor prognostic indicators (low haemoglobin, body mass index)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Transactions of The Royal Society of Tropical Medicine and Hygiene
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
