The urine lipoarabinomannan (LAM) lateral flow assay is a point-of-care test to diagnose HIV-associated tuberculosis (TB). We assessed the performance of urine LAM in HIV-positive patients presenting to the emergency center and evaluated the interobserver agreement between emergency center physicians and laboratory technologists.
A cross-sectional diagnostic study was performed at the emergency center of a district hospital in a high HIV-prevalence community in South Africa.
Consecutive HIV-positive adults presenting with ≥1 WHO TB symptom were enrolled over a 16-month period. A urine LAM test was performed at point-of-care by an emergency physician and interpreted independently by 2 physicians. A second test was performed in the laboratory and interpreted independently by 2 laboratory technologists. The reference standard was a positive TB culture or Xpert MTB/RIF test on sputum or appropriate extrapulmonary samples. We compared diagnostic accuracy and reproducibility of urine LAM between point-of-care readers and laboratory readers.
One thousand three hundred eighty-eight samples (median, 3 samples/participant) were sent for TB microbiology tests in 411 participants; 170 had confirmed TB (41.4%). Point-of-care and laboratory-performed urine LAM had similar sensitivity (41.8% vs 42.0%, P = 1.0) and specificity (90.5% vs 87.5%, P = 0.23). Moderate agreement was found between point-of-care and laboratory testing (κ = 0.62), but there was strong agreement between point-of-care readers (κ = 0.95) and between laboratory readers (κ = 0.94). Positive percent agreement between point-of-care and laboratory readers was 68% and negative percent agreement 92%.
There is no diagnostic accuracy advantage in laboratory-performed versus point-of-care–performed urine LAM tests in emergency care centers in high-burden settings.
aDivision of Emergency Medicine, University of Cape Town, Cape Town, South Africa;
bDivision of Emergency Medicine, Stellenbosch University, Cape Town, South Africa;
cEmergency Centre, Khayelitsha Hospital, Cape Town, South Africa;
dDivision of Medical Microbiology, Department of Pathology, University of Cape Town and National Health Laboratory Service, Cape Town, South Africa;
eDivision of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa; and
fDepartment of Medicine, Centre for Infectious Diseases Research in Africa, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa.
Correspondence to: Daniël J. Van Hoving, MBChB, Dip PEC (SA), MMed (EMed), MMedSci (Clin Epi), Division of Emergency Medicine, Stellenbosch University, PO Box 241, Cape Town 8000, South Africa (e-mail: firstname.lastname@example.org).
G. Meintjes was supported by the Wellcome Trust (098316 and 203135/Z/16/Z), the South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation (NRF) of South Africa (Grant No 64787), NRF incentive funding (UID: 85858), and the South African Medical Research Council through its TB and HIV Collaborating Centres Programme with funds received from the National Department of Health (RFA# SAMRC-RFA-CC: TB/HIV/AIDS-01-2014). G. Maartens was supported by the NRF incentive funding (UID: 85810). The funders had no role in the study design, data collection, data analysis, data interpretation, or writing of this report.
The opinions, findings, and conclusions expressed in this manuscript reflect those of the authors alone. The remaining authors have no funding or conflicts of interest to disclose.
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Received December 18, 2018
Accepted February 04, 2019