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

Abstract

Introduction In Ghana, initiation of Antiretroviral Therapy (ART) is recommended for all patients with an HIV diagnosis, regardless of CD4+ T-cell count. However, measurement of CD4 count remains an important metric for identifying patients with advanced HIV disease, and assessing a person’s overall immune status, which informs the decision to offer opportunistic infection screening and prophylaxis. Access to CD4+ T cell count in rural health facilities remains a major challenge in Ghana and other resource-limited settings. This study aimed to validate the accuracy of the BD FACSPresto near-patient device for measurement of CD4 count and hemoglobin concentration against the FACSCount (CD4) and Sysmex (hemoglobin) diagnostic machines when operated in both a district hospital and rural laboratory, serving a network of health posts in Ashanti Region, Ghana. Methodology In the first phase of the study, patients were recruited from a district hospital, and both venous and capillary blood samples were tested using the FACSCount and Sysmex as reference tests and compared to results of the FACSPresto performed in the clinic laboratory at the district hospital. In the second phase, patients were recruited from both the hospital and from rural health clinics, and samples were tested using the FACSPresto at a rural laboratory. Sensitivity and specificity among samples categorized into different clinically relevant CD4 count ranges were calculated, along with correlation between the Presto and the reference measurements, and mean and relative bias with limits of agreement. Results The FACSPresto was successfully operated in both clinical settings. A total of 59 samples in the first phase and 48 samples in the second phase were included. Positive bias was observed when comparing CD4 count measured by BD FACSPresto to FACSCount in the district hospital (bias = 44, LOA -72,160) and in the rural laboratory setting (bias = 74, LOA -96, 244). In addition, capillary blood samples were shown to give higher measures when compared to venous blood samples from the same participant. All results were statistically significant (p<0.05) apart from hemoglobin measurement in venous blood in the rural laboratory. Correlation coefficients were high for CD4 count measures and lower for hemoglobin measures. Conclusion Overall, the Presto gave higher estimates of CD4 count compared to FACSCount, and hemoglobin measurements were higher than from Sysmex. Samples of capillary blood in turn gave higher results for both measurements compared to venous blood, consistent with previous analyses. These findings should be considered when selecting CD4 count machines for use at the point of care, especially in remote areas where capillary blood sampling may be preferable, but are likely balanced by device’s ease of use, portability, and ability to expand access to services. These results are some of the first to demonstrate the accuracy of the FACSPresto...

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.…”

Performance Evaluation of BD FACSPrestoTM Near-Patient CD4 Counter for Monitoring Antiretroviral Therapy in HIV-Infected Individuals in Primary Healthcare Clinics in Thailand

“…In this study, the percentage and absolute number of CD4 T-lymphocytes obtained from the FACSPresto correlated highly with those from the standard bead-based, threecolor FACSCalibur system both at the ISO15189 certified university hospital's clinical laboratory and the primary healthcare clinics. The performance outcomes for venous blood testing reported here were similar to other previous studies where venous blood sampling was used [15][16][17]19,21]. Most of these studies revealed a consistent over-estimation of percent CD4 T-lymphocyte count of +2.29% (range +0.60% to +6.90%) and +17.70 cells/µL (range −0.78 cells/µL to +44.0 cells/µL) and over-estimation for the absolute CD4 Tlymphocytes (Table 4).…”

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

“…In addition, the hemoglobin test is very important in terms of detecting drug toxicity that develops due to zidovudine, which is frequently used in resource-limited countries. In addition, Zelda et al intimated that it could also be particularly valuable in preventing mother to child transmission (PMTCT) programs (17). The level of the hemoglobin is the best parameter between the two methods that can be compared in our opinion because it is determined in a more standardized way.…”