An increased risk of extracorporeal circuit clotting (ECC) has been reported in patients with coronavirus disease 2019 (COVID-19) admitted to the intensive care unit who require continuous renal replacement therapy.

Recognizing that ECC is a known issue among patients with chronic kidney disease undergoing hemodialysis (HD), which is thought to be due to turbulent blood flow, shear stress, and contact of blood with the dialyzer and other components, the investigators sought to determine whether individuals with COVID-19 who receive intermittent HD have an increased risk of ECC as well.

A single-center, observational review of coagulation studies and HD records was conducted in London, United Kingdom, between April 2020 and June 2021—both 4 weeks before and 4 weeks after the detection of COVID-19 by a nasal or nasopharyngeal polymerase chain reaction (PCR) test—among patients who were receiving HD. Results of the study were published recently in Hemodialysis International.

Overall, 98.1% (203 of 206) of the patients receiving HD who tested positive for COVID-19 underwent clotting studies. The mean participant age was 64.9±15.3 years, and 132 of the patients were male.

It was found that 33.5% (68 of 203) of the patients with COVID-19 who received HD experienced some circuit clotting, with no clotting issues having been reported prior to their positive COVID-19 PCR test results. Among those participants who experienced ECC, prothrombin, activated partial thromboplastin, and thrombin times did not differ from those of patients who did not experience ECC.

In contrast, in patients who experienced ECC vs those who did not, median factor VIII (273 IU/dL vs 166 IU/dL; P <.001), D-dimer (2654 ng/mL vs 1351 ng/mL; P <.05), and fibrinogen (5.6±1.4 g/L vs 4.9±1.4 g/L; P <.05) levels were all significantly greater. Antithrombin, protein C, protein S, and platelet counts did not differ significantly between the groups.

Per the multivariable analysis, those factors independently associated with clotting of dialysis circuits in patients with COVID-19 included log factor VIII (odds ratio [OR], 14.8; 95% confidence limits [CL], 1.12-19.6; P =.041), fibrinogen (OR, 1.57; 95% CL, 1.14-21.7; P =.006), and log D-dimer (OR, 4.8; 95% CL, 1.16-12.5; P =.028).

The researchers concluded that the results of the current analysis suggest that “the risk of circuit clotting was related to the inflammatory response to COVID-19.”


Sudusinghe D, Riddell A, Gandhi T, Chowdary P, Davenport A. Increased risk of dialysis circuit clotting in hemodialysis patients with COVID-19 is associated with elevated FVIII, fibrinogen and D-dimers. Hemodial Int. Published online September 8, 2022. doi:10.1111/hdi.13046