Daniël J Van Hoving1,2, Saʼad Lahri3, Hendrick J Lategan3, Mark P Nicol4, Gary Maartens5, Graeme Meintjes6. 1. Division of Emergency Medicine, University of Cape Town, Cape Town, South Africa. 2. Division of Emergency Medicine, Stellenbosch University, Cape Town, South Africa. 3. Emergency Centre, Khayelitsha Hospital, Cape Town, South Africa. 4. Division of Medical Microbiology, Department of Pathology, University of Cape Town and National Health Laboratory Service, Cape Town, South Africa. 5. Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa. 6. Department of Medicine, Centre for Infectious Diseases Research in Africa, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa.
Abstract
BACKGROUND: 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. SETTING: A cross-sectional diagnostic study was performed at the emergency center of a district hospital in a high HIV-prevalence community in South Africa. METHODS: 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. RESULTS: 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%. CONCLUSION: 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.
BACKGROUND: 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-positivepatients presenting to the emergency center and evaluated the interobserver agreement between emergency center physicians and laboratory technologists. SETTING: A cross-sectional diagnostic study was performed at the emergency center of a district hospital in a high HIV-prevalence community in South Africa. METHODS: 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. RESULTS: 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%. CONCLUSION: 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.
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