Oxygen gradient ektacytometry does not predict pain in children with sickle cell anaemia

Abstract

The loss of red blood cell (RBC) deformability in sickle cell anaemia (SCA) is considered the primary factor responsible for episodes of acute pain and downstream progressive organ dysfunction. Oxygen gradient ektacytometry (Oxygenscan) is a recently commercialised functional assay that aims to describe the deformability of RBCs in SCA at differing oxygen tensions. So far, the Oxygenscan has been evaluated only by a small number of research groups and the validity and clinical value of Oxygenscan-derived biomarkers have not yet been fully established. In this study we examined RBC deformability measured with the Oxygenscan in 91 children with SCA at King's College Hospital in London. We found a significant correlation between Oxygenscan-derived biomarkers and well-recognised modifiers of disease severity in SCA: haemoglobin F and co-inherited a-thalassaemia. We failed, however, to find any independent predictive value of the Oxygenscan in the clinical outcome measure of pain, as well as other important parameters such as hydroxycarbamide treatment. Although the Oxygenscan remains an intriguing tool for basic research, our results question whether it provides any additional information in predicting the clinical course in children with SCA, beyond measuring known markers of disease severity.

OcclusionChip: A functional microcapillary occlusion assay complementary to ektacytometry for detection of small-fraction red blood cells with abnormal deformability

“…In another study, Rab et al showed the impact of the time from blood sampling to measurement, the amount of RBCs during testing, the camera gain settings, and the speed of deoxygenation on the measurements of oxygen gradient ektacytometry and therefore concluded that the standardization of oxygen gradient ektacytometry would allow different laboratories to compare RBC rheology study in SCD ( Rab et al, 2020 ). Moreover, a recent study by Nardo-Marino et al showed that oxygen gradient ektacytometry measurements correlate with key hematological parameters in children with SCD such as Hb levels, HbF, lactate dehydrogenase, and reticulocyte counts ( Nardo-Marino et al, 2021 ). However, this study challenges oxygen gradient ektacytometry that it failed to detect the effect of hydroxyurea (HU) treatment and pain level in the pediatric population.…”

Precision Medicine and Sickle Cell Disease

“…Although studies show that the various ektacytometry parameters correlate with many factors in SCD, such as total hemoglobin and HbF percentage, there is nothing to suggest that this approach offers any additional or independent prognostic information. 44 …”

Determinants of the point of sickling measured by oxygen gradient ektacytometry in sickle cell anaemia

“…7 The mean (SD) HbS and HbF percentages were 82.6 (9.0)% and 13.3 (9.2)%, respectively. The mean (SD) Hb, Hct, MCV and MCHC values were 87 (15) g/l, 27.0 (5.3)%, 83 (13) fl and 343 (15) g/l, respectively. The mean (SD) P50 and PoS values were 29.3 (3.8) mmHg and 44.2 (9.5) mmHg, respectively.…”

“…Rab et al 2 demonstrated that the PoS was higher in both adults and children with SCA with frequent vaso-occlusive crises compared to those with few crises. However, a recent study did not find such a relationship, 13 re-enforcing the need to conduct very large multicentric studies to assess the clinical usefulness of oxygenscan. Oxygenscan is useful to test the biological efficacy of various molecules.…”