The performance of BD FACSPresto™ for CD4 T-cell count, CD4% and hemoglobin concentration test in Ethiopia

Abstract

IntroductionIn Ethiopia, CD4+ T-cell counting is still required for all patients at baseline before antiretroviral therapy (ART) and to determine eligibility and follow-up of opportunistic infection prophylaxis. However, access to CD4+ T cell count in rural health facilities remains a major challenge in Ethiopia like other resource-limited settings.MethodologyBoth capillary and venous blood was drawn from each of 325 study participant recruited in Addis Ababa and surroundings. The CD4+ T-cell count, CD4%, and hemoglobin (Hgb) were tested at one of the four study health facilities using capillary blood and BD FACSPresto™ device. These tests were also done at the national HIV reference laboratory, using venous blood with BD FACSCalibur™, Sysmex XT-1800i™, and BD FACSPresto™.ResultsBD FACSPresto™ had an absolute mean bias of -13.3 cells/ul (-2.99%) and 28.3 cells/μl (6.4%) using venous and capillary blood, respectively, compared with BD FACSCalibur™. The absolute CD4 assay on the BD FACSPresto™ had a regression coefficient (R2) of 0.87 and 0.92 using capillary blood and venous blood samples, respectively, compared with BD FACSCalibur™. The percentage similarity of the BD FACSPresto™ using capillary and venous blood was 105.2% and 99.3%, respectively. The sensitivity of the FACSPresto™ using threshold of 500 cells/μl for ART eligibility using capillary and venous blood was 87.9 and 94.3%, while the specificity was 91.4 and 83.8%, respectively. Furthermore, the BD FACSPresto™ had an absolute mean bias of -0.2 dl/μl (0.0%) (95% LOA: -1.7, 1.3) and -0.59 dl/μl (0.1%) (95% LOA: -1.49, 0.31) for Hgb using capillary and venous blood compared with the Sysmex XT-1800i™, respectively.ConclusionOur results showed acceptable agreement between the BD FACSPresto™ and BD FACSCalibur™ for CD4+ T-cell counting and CD4%; and between the BD FACSPresto™ and Sysmex XT-1800i™for measuring Hgb concentration.

Performance of the BD-FACS Presto for CD4 count and hemoglobin measurement in a district hospital and rural laboratory in Ghana

“…Reliable CD4 count testing is needed in health facilities to monitor the immune status of PLHIV, even as access to VL monitoring expands. This study found that the Presto overestimates CD4 count in comparison to FACSCount, which is consistent with other studies comparing Presto to FACSCount or FACSCalibur [19–21, 23], though one study in Ethiopia did find a negative bias of 13.3 cells/μl when comparing Presto to FACSCalibur [16]. Overall, the accuracy of the Presto machine must be considered, since over-estimation of CD4 count could result in missing cases of advanced HIV disease, and overestimation of Hgb concentration could result in missed cases of anemia.…”

“…It has been validated previously against the BD FACSCalibur and BD FACSCount in several countries in Eastern and Southern Africa, predominantly in urban reference laboratory or hospital settings, with limited data on performance in rural settings. Its diagnostic accuracy was assessed in a district hospital, an advanced laboratory (Kenya Medical Research Institute/CDC) and in a community level facility in Kenya [8, 19, 21]; at an urban HIV clinic in Johannesburg, South Africa [22], at a hospital-affiliated HIV clinic in Harare, Zimbabwe [20], at a secondary hospital in Nigeria [23] and at four urban facilities in Ethiopia [16]; additionally, a multi-site evaluation took place in hospitals in Kenya, Thailand, San Francisco, and India [14], as well as in reference laboratories in Belgium and Tanzania [15]. Seven out of ten studies reviewed found that Presto over-estimated CD4 count when compared to the reference standard (FACSCount or FACSCalibur).…”

“…Seven out of ten studies reviewed found that Presto over-estimated CD4 count when compared to the reference standard (FACSCount or FACSCalibur). Mean biases ranged from -13.3 cells/μl [16] to +77.16 cells/μl [19]. In addition, all studies comparing venous samples to capillary samples found that capillary samples give a systematically higher estimation of absolute and/or relative CD4 count.…”

Validation of the BD FACSPresto system for the measurement of CD4 T-lymphocytes and hemoglobin concentration in HIV-negative and HIV-positive subjects

“…Further strengthening the results of our study, another study by Angira et al assessed the performance of the BD FACSPresto system and further evaluated its accuracy, stability, linearity, precision, and reference intervals using capillary and venous blood of HIV-positive patients from Kenya; the Deming regression slopes for AbsCD4 and CD4% (venous/capillary) were within 0.97–1.03 and R 2 was ≥ 0.96; while slope and R 2 values were ≥ 0.94 for Hb 26 . Furthermore, in line with several previously published studies 23 , 26 , 31 , 32 , Bland–Altman analyses demonstrated close agreement between the BD FACSPresto system and the reference standards for all study participants. A notable advantage of the BD FACSPresto system is that testing can be performed using the finger-prick (capillary) blood sample without compromising the accuracy of analytical results, thus simplifying and improving the efficiency of diagnostics for HIV/AIDS.…”

Comparison of Standard and Point of Care CD4+ T Lymphocyte Measurement Methods in HIV-1 Infected Turkish Patients

“…Today, c-ART has been started for every patient diagnosed with chronic HIV infection independent of the CD4 + T lymphocyte count (10). Countries suffering a high HIV burden in sub-Saharan Africa are left with di cult decisions of when and how to implement the many new recommendations in resource-limited settings (19). Assessing the immune status in patients through POC CD4 + T lymphocyte count can identify advanced HIV disease, which should be prioritized for prophylaxis of opportunistic infections even if they are asymptomatic.…”