WHO multicenter evaluation of FACSCount CD4 and Pima CD4 T-cell count systems: Instrument performance and misclassification of HIV-infected patients
Journal of Acquired Immune Deficiency Syndromes
Laboratory of Immunology, Department of Biomedical Sciences, Institute of Tropical Medicine Antwerp, Antwerp, Belgium; Unit of Immunology, Laboratory of Bacteriology Virology, University Cheikh Anta Diop, Dakar, 92000, Senegal; Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium; Department of Microbiology and Immunology, Muhimbili University of Health and Allied Sciences, Dar es Salam, Tanzania; World Health Organization, Geneva, Switzerland
BACKGROUND: CD4 T-cell counts are used to screen and follow-up HIV-infected patients during treatment. As part of the World Health Organization prequalification program of diagnostics, we conducted an independent multicenter evaluation of the FACSCount CD4 and the Pima CD4, using the FACSCalibur as reference method. METHODS: A total of 440 paired capillary and venous blood samples were collected from HIV-infected patients attending the HIV outpatient clinic in Antwerp, Belgium, and the HIV care and treatment center in Dar es Salam, Tanzania. Capillary blood was run on Pima analyzer, whereas venous blood was analyzed on FACSCount, Pima, and FACSCalibur instruments. Precision and agreement between methods were assessed. RESULTS: The FACSCount CD4 results were in agreement with the FACSCalibur results with relative bias of 0.4% and 3.1% on absolute CD4 counts and an absolute bias of -0.6% and -1.1% on CD4% in Antwerp and Dar es Salam, respectively. The Pima CD4 results were in agreement with the FACSCalibur results with relative bias of -4.1% and -9.4% using venous blood and of -9.5% and -0.9% using capillary blood in Antwerp and Dar es Salam, respectively. At the threshold of 350 cells per microliter, the FACSCount CD4 and Pima CD4 using venous and capillary blood misclassified 7%, 9%, and 13% of patients, respectively. CONCLUSIONS: The FACSCount CD4 provides reliable CD4 counts and CD4% and is suitable for monitoring adult and pediatric HIV patients in moderate-volume settings. The Pima CD4 is more suitable for screening eligible adult HIV patients for antiretroviral treatment initiation in low-volume laboratories. Copyright © 2014 by Lippincott Williams & Wilkins.
adolescent; adult; aged; article; Belgium; blood sampling; capillary blood; CD4 lymphocyte count; CD4 T cell count test; clinical assessment; female; human; Human immunodeficiency virus infected patient; intermethod comparison; major clinical study; male; measurement accuracy; multicenter study; outpatient department; priority journal; Tanzania; venous blood; Adult; Aged; Aged, 80 and over; Belgium; CD4 Lymphocyte Count; Female; HIV Infections; Humans; Male; Middle Aged; Sensitivity and Specificity; Tanzania; Young Adult