Accurate and reproducible enumeration of CD4 T cell counts and Hemoglobin levels using a point of care system: Comparison with conventional laboratory based testing systems in a clinical reference laboratory in Cameroon.

BACKGROUND: Measurements of CD4 T cells and hemoglobin (Hb) are conventionally used to determine the immunological state and disease progression for HIV-infected patients. We obtained a small lightweight point-of-care device, the BD FACSPrestoTM in order to demonstrate its ability to deliver CD4 and Hb analysis in comparison with two larger clinical machines the BDFACSCantoTM analyzer and Sysmex XN 1000 haematology analyzer. The advantages of using the POC device include access to HIV patient data in remote and in resource limited settings.

METHOD: The analytical performance of the BD FACSPrestoTM, compared with the FACSCantoTM II flow cytometer and the Sysmex XN 1000 haematology analyzer was evaluated by testing 241 routine clinical specimens collected in EDTA tubes from patients attending the Immunology and Microbiology laboratory of Chantal BIYA International Reference Centre (Yaounde, Cameroon) between January and May 2016.

RESULTS: The mean in absolute counts and percentage of CD4 T cells was 606 cells/mL and 25% respectively via the FACSPrestoTM, and 574 cells/mL and 24% respectively via the BD FACSCantoTM II. The mean concentration of Hb levels was 11.90 on the Sysmex XN 1000 and 11.45 via the BD FACSPrestoTM, A high correlation (R2 = 0.95, P < 0.001) of Hb level measurements was noted between the BD FACSPrestoTM and Sysmex XN 1000 hematology analyzer. Overall, a Bland-Altman plot of the differences between the two methods showed an excellent agreement for absolute and percentage CD4 counts and hemoglobin measurements between POC and conventional methods evaluated here. Furthermore, the study demonstrated the ease of use of the BD FACSPrestoTM POC technology in remote areas.

CONCLUSION: The BD FACPrestoTM is a suitable tool for CD4 enumeration in resource-limited settings, specifically providing a deployable, reliable POC testing option. The BD FACSPrestoTM performed appropriately in comparison to the conventional reference standard technologies. The BD FACSPrestoTM, system provides accurate, reliable, precise CD4/%CD4/Hb results on venous blood sampling. The data showed good agreement between the BD FACSPrestoTM, BD FACSCantoTM II and Sysmex XN 1000 XN 1000 systems.