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

Introduction In 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. Methodology Both 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 (TM) device. These tests were also done at the national HIV reference laboratory, using venous blood with BD FACSCalibur (TM), Sysmex XT-1800i (TM), and BD FACSPresto (TM). Results BD FACSPresto (TM) had an absolute mean bias of -13.3 cells/mu l (-2.99%) and 28.3 cells/mu l (6.4%) using venous and capillary blood, respectively, compared with BD FACSCalibur (TM). The absolute CD4 assay on the BD FACSPresto (TM) had a regression coefficient (R-2) of 0.87 and 0.92 using capillary blood and venous blood samples, respectively, compared with BD FACSCalibur (TM). The percentage similarity of the BD FACSPresto (TM) using capillary and venous blood was 105.2% and 99.3%, respectively. The sensitivity of the FACSPresto (TM) using threshold of 500 cells/mu l 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 (TM) had an absolute mean bias of -0.2 dl/mu l (0.0%) (95% LOA: -1.7, 1.3) and -0.59 dl/mu l (0.1%) (95% LOA: -1.49, 0.31) for Hgb using capillary and venous blood compared with the Sysmex XT-1800i (TM), respectively. Conclusion Our results showed acceptable agreement between the BD FACSPresto (TM) and BD FACS-Calibur (TM) for CD4+ T-cell counting and CD4%; and between the BD FACSPresto (TM) and Sysmex XT-1800i (TM) for measuring Hgb concentration.