Laboratory and Field Evaluation of the Partec CyFlow MiniPOC for Absolute and Relative CD4 T-Cell Enumeration

Abstract

BackgroundA new CD4 point-of-care instrument, the CyFlow miniPOC, which provides absolute and percentage CD4 T-cells, used for screening and monitoring of HIV-infected patients in resource-limited settings, was introduced recently. We assessed the performance of this novel instrument in a reference laboratory and in a field setting in Senegal.MethodologyA total of 321 blood samples were obtained from 297 adults and 24 children, all HIV-patients attending university hospitals in Dakar, or health centers in Ziguinchor. Samples were analyzed in parallel on CyFlow miniPOC, FACSCount CD4 and FACSCalibur to assess CyFlow miniPOC precision and accuracy.ResultsAt the reference lab, CyFlow miniPOC, compared to FACSCalibur, showed an absolute mean bias of -12.6 cells/mm3 and a corresponding relative mean bias of -2.3% for absolute CD4 counts. For CD4 percentages, the absolute mean bias was -0.1%. Compared to FACSCount CD4, the absolute and relative mean biases were -31.2 cells/mm3 and -4.7%, respectively, for CD4 counts, whereas the absolute mean bias for CD4 percentages was 1.3%. The CyFlow miniPOC was able to classify HIV-patients eligible for ART with a sensitivity of ≥ 95% at the different ART-initiation thresholds (200, 350 and 500 CD4 cells/mm3). In the field lab, the room temperature ranged from 30 to 35°C during the working hours. At those temperatures, the CyFlow miniPOC, compared to FACSCount CD4, had an absolute and relative mean bias of 7.6 cells/mm3 and 2.8%, respectively, for absolute CD4 counts, and an absolute mean bias of 0.4% for CD4 percentages. The CyFlow miniPOC showed sensitivity equal or greater than 94%.ConclusionThe CyFlow miniPOC showed high agreement with FACSCalibur and FACSCount CD4. The CyFlow miniPOC provides both reliable absolute CD4 counts and CD4 percentages even under the field conditions, and is suitable for monitoring HIV-infected patients in resource-limited settings.

Performance Evaluation of the Becton Dickinson FACSPresto™ Near-Patient CD4 Instrument in a Laboratory and Typical Field Clinic Setting in South Africa

“…Simpler disposable lateral flow strip systems like Visitect (Omega Diagnostics) and Zyomyx MyT4 (Mylan, USA) offer instrument free options [ 18 – 21 ]. Several published papers describe validation of these systems with varying approaches, reference platforms and outcomes [ 22 – 26 ]. The PIMA point-of-care instrument has been commercially available the longest and several validation, implementation and costing studies have been reported, including a recent meta-analysis of POC technology [ 11 , 26 – 33 ].…”

Evaluation of the FACSPresto, a New Point of Care Device for the Enumeration of CD4% and Absolute CD4+ T Cell Counts in HIV Infection

“…The CyFlow miniPOC is based on flow cytometry and has been recently evaluated. Compared with the FACSCalibur (BD Biosciences) and FACSCount (BD Biosciences) as reference standards it showed low relative bias and good sensitivity at WHO defined thresholds[ 9 ]. The assay is performed on venous blood, has a rapid specimen processing time allowing for up to 250 patient tests/day and also enumerates CD4% values.…”

Rapid, label-free CD4 testing using a smartphone compatible device

“…To put the performance of our device into context, the commercially available Alere PIMA™ has shown 94% and 96% sensitivities at 200 and 500 cells/μL thresholds, respectively 29, 30 . Similarly, the sensitivity of CyFlow® miniPOC was >95% at 200, 350 and 500 cells/μL thresholds 31 . It is important to keep in mind that the performance of these systems were observed in the field, and further field-validation is required with our presented system before direct comparisons can be made.…”