Analysis Of Hemostatic Characteristics using Thromboelastometry in Adults With Sickle Cell Disease and Controls
Authors: Janbain Maissaa , Leissinger Cindy A. , Kruse-Jarres Rebecca 
Published: October 2019

Background
Vaso-occlusive phenomena and hemolysis are the clinical hallmarks of sickle cell disease (SCD). In addition, pain crisis was identified as the initial clinical manifestation in 61.9% of sickle cell patients who died shortly after hospital admission from thromboembolism and micro vascular thrombi. Knowing that the vaso-occlusive events may be related to activation of the hemostatic system, and that thromboelastometry (TEM) assesses the functionality of this system from a global standpoint, it will be challenging to characterize the findings in patients with SCD as a way to differentiate their clinical phenotype upon presentation, and to predict the impact of these manifestations on their prognosis, mortality and morbidity.

Objective
To characterize the findings of TEM in patients with SCD during periods of steady state and acute illness, to compare these results with those of healthy controls and sickle cell trait (SCT), to compare the findings in whole blood (WB) to plasma (PL) for each category, in a way to analyze the findings in plasma and their applicability in clinical practice as well as to delineate the contribution of the cellular component in whole blood samples.

Design
In a cross-sectional study, we obtained TEM and other hemostatic data on 24 adult patients with SCD (16 in steady state and 8 in acute illness); and 13 race and age matched healthy controls (6 with sickle cell trait (SCT) and 7 with no trait). We specifically studied coagulation time (CT) as a function of coagulation factors; clot firmness time (CFT) and alpha angle(α) assessing platelet and fibrinogen function; and maximum clot firmness (MCF) evaluating the mechanical clot quality (plt, fibrinogen and factorXIII) and finally thrombodynamic potential index (TPI) as a function of patient’s global coagulation.

Results
Overall, patients with SCD had higher TPI in WB (p=0.23;=0.25) and lower TPI in PL (p<0.0001;=0.47) when compared to controls and SCT respectively. Also, patients with SCD had lower CT (p=0.02), lower CFT (p<0.0001) higher MCF; α and TPI (p<0.0001; =0.051; <0.0001) in whole blood compared to plasma. Sickle cell trait patients had lower CT, CFT, alpha with higher MCF in WB compared to PL. While healthy controls had higher CT; MCF and TPI (p=0.01; <0.0001; <0.0001) and lower CFT, α (p=0.16; <0.0001) in WB compared to PL.

Conclusion
Whole blood of SCD patients seems to be hypercoagulable in comparison to WB of controls and SCT. While the plasma of SCD patients was significantly hypocoagulable when compared to PL of healthy controls. Overall, TEG profiles of WB were different than PL. This was more obvious in SCD patients reinforcing the contribution of the cellular component to the pathophysiology of this disease and the possible compensatory hypocoagulable status of the plasma in these patients. Further study of larger and more homogeneous patient groups, is required to adequately assess the clinical utility of TEM in patients with sickle cell disease.

Disclosures:
Kruse-Jarres: Baxter Healthcare: Consultancy; Bayer HealthCare: Consultancy; Biogen IDEC: Consultancy; Grifols: Consultancy; Kedrion: Consultancy; Novo Nordisk: Consultancy.