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Clinical Utility of a Commercial LAM-ELISA Assay for TB Diagnosis in HIV-Infected Patients Using Urine and Sputum Samples

Dheda, K; Davids, V; Lenders, L; Roberts, T; Meldau, R; Ling, D; Brunet, L; ... Zumla, A; + view all (2010) Clinical Utility of a Commercial LAM-ELISA Assay for TB Diagnosis in HIV-Infected Patients Using Urine and Sputum Samples. PLOS ONE , 5 (3) , Article e9848. 10.1371/journal.pone.0009848. Green open access

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Abstract

Background: The accurate diagnosis of TB in HIV-infected patients, particularly with advanced immunosuppression, is difficult. Recent studies indicate that a lipoarabinomannan (LAM) assay (Clearview-TB (R)-ELISA) may have some utility for the diagnosis of TB in HIV-infected patients; however, the precise subgroup that may benefit from this technology requires clarification. The utility of LAM in sputum samples has, hitherto, not been evaluated.Methods: LAM was measured in sputum and urine samples obtained from 500 consecutively recruited ambulant patients, with suspected TB, from 2 primary care clinics in South Africa. Culture positivity for M. tuberculosis was used as the reference standard for TB diagnosis.Results: Of 440 evaluable patients 120/387 (31%) were HIV-infected. Urine-LAM positivity was associated with HIV positivity (p = 0.007) and test sensitivity, although low, was significantly higher in HIV-infected compared to uninfected patients (21% versus 6%; p<0.001), and also in HIV-infected participants with a CD4 <200 versus <200 cells/mm(3) (37% versus 0%; p = 0.003). Urine-LAM remained highly specific in all 3 subgroups (95%-100%). 25% of smear-negative but culture-positive HIV-infected patients with a CD4 <200 cells/mm(3) were positive for urine-LAM. Sputum-LAM had good sensitivity (86%) but poor specificity (15%) likely due to test cross-reactivity with several mouth-residing organisms including actinomycetes and nocardia species.Conclusions: These preliminary data indicate that in a high burden primary care setting the diagnostic usefulness of urine-LAM is limited, as a rule-in test, to a specific patient subgroup i.e. smear-negative HIV-infected TB patients with a CD4 count <200 cells/mm(3), who would otherwise have required further investigation. However, even in this group sensitivity was modest. Future and adequately powered studies in a primary care setting should now specifically target patients with suspected TB who have advanced HIV infection.

Type: Article
Title: Clinical Utility of a Commercial LAM-ELISA Assay for TB Diagnosis in HIV-Infected Patients Using Urine and Sputum Samples
Open access status: An open access version is available from UCL Discovery
DOI: 10.1371/journal.pone.0009848
Publisher version: http://dx.doi.org/10.1371/journal.pone.0009848
Language: English
Additional information: © 2010 Dheda et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This study was supported by a TBsusgent grant from the European Commission (EU-FP7; K.D., M.P., M.H.), Europe AID ADAT grant (A.Z. and M.H.), EDCTP (M.H., K.D. and A.Z.), UK Cambridge Biomedical Research Centre (CBRC), National Institute for Health Research (NIHR) (A.Z.), and in by part by the Canadian Institutes of Health Research (CIHR) grant MOP-89918; M.P., K.D.). K.D. is also supported by a Medical Research Council (MRC) Career Development Award and a NRF/SARChI award, and M.P. by a CIHR New Investigator Award. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Keywords: MYCOBACTERIAL LIPOARABINOMANNAN, ACTIVE TUBERCULOSIS, BURDEN, NEPHROPATHY, SETTINGS
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Infection and Immunity
URI: https://discovery.ucl.ac.uk/id/eprint/119277
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