# Thromboelastography in COVID-19 patients: An observational study in the South African context

## TL;DR

This study explores if thromboelastography can be a more accessible alternative to anti-Xa testing for monitoring blood clotting in patients with COVID-19 receiving heparin.

## Contribution

The study evaluates the correlation between thromboelastogram parameters and anti-Xa levels in South African patients with COVID-19.

## Key findings

- Thromboelastogram coagulation index moderately correlated with anti-Xa levels (rs 0.43).
- R-time showed a moderate correlation (rs 0.52) with anti-Xa levels.
- K-time had a low correlation (rs 0.35) with anti-Xa levels.

## Abstract

Coronavirus disease 2019 (COVID-19) increases the risk of venous thromboembolism, requiring monitoring of low molecular weight heparin (LMWH) via a time-consuming, costly and often unavailable test – anti-factor Xa (anti-Xa). An affordable, rapid point-of-care alternative, the thromboelastogram, is available, but performance comparisons to anti-Xa are lacking.

This study evaluated the relationship between anti-Xa and thromboelastogram in patients with COVID-19 receiving LMWH.

This was a retrospective study of patients with COVID-19 receiving LMWH at Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa, between November 2020 and January 2021. Blood samples tested with thromboelastogram and anti-Xa were drawn at three timepoints (one prior to and two after administration of LMWH). Thromboelastogram parameters comprised reaction time (R-time; onset of testing to the start of clot formation), kinetics time (K-time; start of clot formation until the clot reached 20 mm), and thromboelastogram coagulation index (overall coagulation status of whole blood).

Forty-two patients with COVID-19 (15 male and 27 female) met the study criteria. There was a statistically significant, low to moderate correlation (Spearman’s correlation coefficient [rs 0.43, p = 0.014]) between anti-Xa and thromboelastogram coagulation index. A statistically significant moderate correlation (rs 0.52, p = 0.002) between anti-Xa and R-time, and a statistically significant low correlation (rs 0.35, p = 0.049) between anti-Xa and K-time, were found. All correlations were 48 h post admission.

Thromboelastogram coagulation index, R-times and K-times had a statistically significant association with anti-Xa levels in patients with COVID-19. Further research is required regarding their clinical utility.

Thromboelastograms may represent a more cost-effective and accessible option to the conventional anti-Xa test in patients receiving LMWH. However, future research with larger sample sizes, varying disease profiles, and severity of illness is required.