Contrived blood samples spiked with a range of elevated levels of AGP, CRP, HRP2 and sTfR.

Contrived blood samples spiked with a range of elevated levels of AGP, CRP, HRP2 and sTfR.</p

Fig 3 -

A. Lin’s concordance correlation coefficient (CCC) plots comparing the analyte measurements in paired wet plasma (x-axes) and DBS samples (y-axes). AGP, α-1-acid glycoprotein; CRP, C-reactive protein; FER, ferritin; HRP2, histidine rich protein 2; RBP4, retinol binding protein 4; sTfR, soluble transferrin receptor; Tg, thyroglobulin; DBS, dried blood spot; rho_c, CCC. B, Lin’s CCC plots comparing the analyte measurements in paired wet plasma (x-axes) and the adjusted PCD (y-axes). AGP, α-1-acid glycoprotein; CRP, C-reactive protein; FER, ferritin; HRP2, histidine rich protein 2; RBP4, retinol binding protein 4; sTfR, soluble transferrin receptor; Tg, thyroglobulin; DBS, dried blood spot; rho_c, CCC.</p

Schematic illustrating the plasma collection disc in operation.

The schematic illustrates a single PCD. Photos on the left show the PCD with the the filter disc placed on a manifold for multiple samples and the addition of 35 μL of whole blood to each disc (top), a PDC detail view prior to whole blood being added (middle), and the discs after blood has been absorbed and finally the plasma collection disc exposed after the whole blood treated filter has been removed (bottom). The disc is removed with sterile forceps and is ready for use or can be stored until required.</p

Summary statistics and cross-laboratory coefficients of variation (CV) for plasma, DBS and PCD.

Summary statistics and cross-laboratory coefficients of variation (CV) for plasma, DBS and PCD.</p

CareStart G6PD biosensor.

<p>The device consolidates a hemoglobin measurement device (on the left) with a G6PD activity measurement device (on the right). Two disposables and samples are therefore required, one of each analyte measurement. The device then calculates the G6PD activity normalized for hemoglobin concentration based on the two measurements.</p

The comparison of results for plasma, DBS and the volume adjusted PCD eluates using <i>R</i>_<i>s</i> and recovery of expected plasma values.

The comparison of results for plasma, DBS and the volume adjusted PCD eluates using Rs and recovery of expected plasma values.</p

Sample panels and experiment design.

Sample panels and experiment design.</p

Fig 4 -

A. Bland Altman plots of the difference in results derived from wet plasma versus DBS types measured using the 7-plex assay. Average of the wet plasma and dry sample type (x-axes) are plotted against the difference between measurements from the 7-Plex assay for paired wet plasma and dry sample types (y-axes). B. Bland Altman plots of the difference in results derived from wet plasma versus the adjusted PCD. For both Figures, the horizontal lines indicate line of perfect agreement (green), mean (purple), and ± 2standard deviations of the difference (red). AGP, α-1-acid glycoprotein; CRP, C-reactive protein; FER, ferritin; HRP2, histidine rich protein 2; RBP4, retinol binding protein 4; sTfR, soluble transferrin receptor; Tg, thyroglobulin; DBS, dried blood spot.</p

Validation of the quantitative point-of-care CareStart biosensor for assessment of G6PD activity in venous blood

<div><p>Introduction</p><p>Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymopathy in the human population affecting an estimated 8% of the world population, especially those living in areas of past and present malaria endemicity. Decreased G6PD enzymatic activity is associated with drug-induced hemolysis and increased risk of severe neonatal hyperbilirubinemia leading to brain damage. The G6PD gene is on the X chromosome therefore mutations cause enzymatic deficiency in hemizygote males and homozygote females while the majority of heterozygous females have an intermediate activity (between 30–80% of normal) with a large distribution into the range of deficiency and normality. Current G6PD qualitative tests are unable to diagnose G6PD intermediate activities which could hinder wide use of 8-aminoquinolines for <i>Plasmodium vivax</i> elimination. The aim of the study was to assess the diagnostic performances of the new Carestart G6PD quantitative biosensor.</p><p>Methods</p><p>A total of 150 samples of venous blood with G6PD deficient, intermediate and normal phenotypes were collected among healthy volunteers living along the north-western Thailand-Myanmar border. Samples were analyzed by complete blood count, by gold standard spectrophotometric assay using Trinity kits and by the latest model of Carestart G6PD biosensor which analyzes both G6PD and hemoglobin.</p><p>Results</p><p>Bland-Altman comparison of the CareStart normalized G6PD values to that of the gold standard assay showed a strong bias in values resulting in poor area under-the-curve values for both 30% and 80% thresholds. Performing a receiver operator curve identified threshold values for the CareStart product equivalent to the 30% and 80% gold standard values with good sensitivity and specificity values, 100% and 92% (for 30% G6PD activity) and 92% and 94% (for 80% activity) respectively.</p><p>Conclusion</p><p>The Carestart G6PD biosensor represents a significant improvement for quantitative diagnosis of G6PD deficiency over previous versions. Further improvements and validation studies are required to assess its utility for informing radical cure decisions in malaria endemic settings.</p></div

Threshold normalized G6PD activity values on the CareStart biosensor optimized to maximize sensitivity and specificity using Youden’s Index.

<p>Threshold normalized G6PD activity values on the CareStart biosensor optimized to maximize sensitivity and specificity using Youden’s Index.</p