title: Performance Evaluation of the Becton Dickinson FACSPresto™ Near-Patient CD4 Instrument in a Laboratory and Typical Field Clinic Setting in South Africa.
abstract: BACKGROUND
  The 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.
  
  
  METHODS
  Phase-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%).
  
  
  RESULTS
  In 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.
  
  
  CONCLUSIONS
  The 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.
authors.affiliation: National Health Laboratory Service of South Africa (NHLS), Charlotte Maxeke Hospital, CD4 Laboratory, Parktown, Johannesburg, South Africa.|Department of Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2198, Johannesburg, South Africa.
authors.forename: Lindi-Marie
authors.initials: LM
authors.lastname: Coetzee
authors.affiliation: Department of Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2198, Johannesburg, South Africa.
authors.forename: Keshendree
authors.initials: K
authors.lastname: Moodley
authors.affiliation: National Health Laboratory Service of South Africa (NHLS), Charlotte Maxeke Hospital, CD4 Laboratory, Parktown, Johannesburg, South Africa.|Department of Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2198, Johannesburg, South Africa.
authors.forename: Deborah Kim
authors.initials: DK
authors.lastname: Glencross
mesh_terms: D000328:Adult; D018791:CD4 Lymphocyte Count / Q000379:methods* / Q000592:standards; D005260:Female; D015658:HIV Infections / Q000097:blood* / Q000175:diagnosis* / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013019:South Africa