Diagnostic accuracy of commercial urinary lipoarabinomannan detection in African tuberculosis suspects and patients
Abstract:OBJECTIVE: To evaluate a commercially available antigen capture enzyme-linked immunosorbent assay (ELISA) based on detecting lipoarabinomannan (LAM) in urine for the diagnosis of tuberculosis (TB).
DESIGN: Consenting TB suspects and registering TB patients prospectively recruited from three hospitals were asked for two sputum specimens for microscopy and culture, urine for LAM testing and blood for human immunodeficiency virus (HIV) testing, with radiological and clinical follow-up for 2 months.
RESULTS: Of 427 participants, complete data were available from 397 (307 adult and 23 adolescent TB suspects, and 67 registering TB patients). HIV prevalence was 77%. TB was diagnosed in 195 (49%), including 161 culture-positive patients, and confidently excluded in 114 (29%) participants. LAM ELISA sensitivity was 44% (95%CI 36–52) for culture-confirmed TB (52% in smear-positive patients). Specificity was 89% (95%CI 81–94). Sensitivity was significantly higher in HIV-related TB (52%, 95%CI 43-62, P < 0.001) compared to HIV-negative TB (21%, 95%CI 9–37). Sensitivity in smear-negative patients was low (28%, 95%CI 13–43) for combined HIV-positive and -negative patients.
CONCLUSION: Our findings confirm greater sensitivity of urine LAM detection for HIV-related TB. However, both sensitivity and specificity were suboptimal, suggesting that this version cannot confirm or exclude TB in either HIV-infected or non-infected patients.
Document Type: Regular Paper
Affiliations: 1: Biomedical Research and Training Institute, Harare, Zimbabwe 2: Foundation for Innovative and New Diagnostics, Geneva, Switzerland 3: Public Health Laboratories, Ministry of Health, Harare, Zimbabwe 4: Harare City Health, Harare, Zimbabwe 5: Biomedical Research and Training Institute, Harare, Zimbabwe; and Clinical Research Unit, London School of Hygiene & Tropical Medicine, London, UK 6: Biomedical Research and Training Institute, Harare, Zimbabwe; and University of Zimbabwe College of Health Sciences, Harare, Zimbabwe
Publication date: October 1, 2009
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