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

Abstract

BackgroundThe BD-FACSPresto™ CD4 is a new, point-of-care (POC) instrument utilising finger-stick capillary blood sampling. This study evaluated its performance against predicate CD4 testing in South Africa.MethodsPhase-I testing: HIV+ patient samples (n = 214) were analysed on the Presto™ under ideal laboratory conditions using venous blood. During Phase-II, 135 patients were capillary-bled for CD4 testing on FACSPresto™, performed according to manufacturer instruction. Comparative statistical analyses against predicate PLG/CD4 method and industry standards were done using GraphPad Prism 6. It included Bland-Altman with 95% limits of agreement (LOA) and percentage similarity with coefficient of variation (%CV) analyses for absolute CD4 count (cells/μl) and CD4 percentage of lymphocytes (CD4%).ResultsIn Phase-I, 179/217 samples yielded reportable results with Presto™ using venous blood filled cartridges. Compared to predicate, a mean bias of 40.4±45.8 (LOA of -49.2 to 130.2) and %similarity (%CV) of 106.1%±7.75 (7.3%) was noted for CD4 absolute counts. In Phase-2 field study, 118/135 capillary-bled Presto™ samples resulted CD4 parameters. Compared to predicate, a mean bias of 50.2±92.8 (LOA of -131.7 to 232) with %similarity (%CV) 105%±10.8 (10.3%), and 2.87±2.7 (LOA of -8.2 to 2.5) with similarity of 94.7±6.5% (6.83%) noted for absolute CD4 and CD4% respectively. No significant clinical differences were indicated for either parameter using two sampling methods.ConclusionThe Presto™ produced remarkable precision to predicate methods, irrespective of venous or capillary blood sampling. A consistent, clinically insignificant over-estimation (5–7%) of counts against PLG/CD4 and equivalency to FACSCount™ was noted. Further field studies are awaited to confirm longer-term use.

Performance of FACSPresto Point-of-Care Instrument for CD4-T Cell Enumeration in Human Immunodeficiency Virus (HIV)-Infected Patients Attending Care and Treatment Clinics in Belgium and Tanzania

“…We found a slight overestimation of the absolute counts, similar to the one observed for other CD4-dedicated bench top instruments like the FACSCount [ 13 ]. Results from Dar es Salaam were also perfectly in line with FACSPresto results obtained in two other studies recently conducted in Africa [ 15 ; 16 ]. Correlation and clinical misclassification of patients based on capillary blood results were also in agreement with the previous studies [ 14 – 16 ].…”

Performance of the BD FACSPresto near to patient Analyzer in comparison with representative conventional CD4 instruments in Cameroon.

“…It will also reduce queues while reducing patient visits to health facilities as patients with immunodeficiency are prioritized and expected to reduce energy costs. Similar studies have been done in Kenya and many other countries using whole blood with EDTA anticoagulant and capillary blood to see the correlation [19][20][21][22][23]. The slight discrepancy between the individual results of BD FACSPresto ™ and other devices in this study was similar to those seen and accepted in other comparisons of conventional CD4 technologies.…”

Performance of the BD FACSPresto near to patient Analyzer in comparison with representative conventional CD4 instruments in Cameroon.

“…It will also reduce queues while reducing patient visits to health facilities as patients with immunode ciency are prioritized and expected to reduce energy costs. Similar studies have been done in Kenya and many other countries using whole blood with EDTA anticoagulant and capillary blood to see the correlation [20][21][22][23][24]. The slight discrepancy between the individual results of BD FACSPresto ™ and other devices in this study was similar to those seen and accepted in other comparisons of conventional CD4 technologies.…”