Impact of Dialysis Modality on Coagulation and Platelet Function in Critically Ill Patients: Intermittent Hemodialysis vs. Continuous Renal Replacement Therapy
Conditions: Renal Replacement Therapy
Sponsor: Seoul National University Hospital

1 
 
Title of the study:  
Impact of renal replacement therapy modality on coagulation and platelet function 
in critically ill patients: Intermittent hemodialysis vs. continuous renal replacement 
therapy 
 
The National Clinical Trial (NCT) number: NCT04512131 
Date of the documenta: December 20, 2023 
 
Study Protocol wih Statistical Analysis Plan (SAP) 
  
Study Protocol 
Study design and patients  
This was a single-center prospective observational study. The institutional review 
board at Seoul National University Hospital approved the protocol (H-2007-102-1141). 
Patients or their surrogates provided written informed consent before enrollment.  
Adult patients admitted to a surgical or medical intensive care unit (ICU) and were 
underwent a session of iHD or at least 48 hours of CRRT or both modalities between 
August 2020 and January 2023 were included. Patients were excluded if they fulfilled 
one of the following criteria: duration of CRRT was less than 48 hours, received platelet 
concentrates, fresh frozen plasma, or cryoprecipitate, discontinuation or initiation of the 
antiplatelet agents or anticoagulants during the study period, technical errors in laboratory 
tests.  
 
Renal replacement therapy  

2 
 
All patients underwent either iHD or CRRT or both, according to the clinical 
situation. The detailed setting of RRT including blood flow rate, dialysis flow rate, 
ultrafiltration rate, duration, and use of anticoagulants was determined by nephrologists 
and intensivists. Patients were divided into the iHD or CRRT group according to the 
applied RRT modality. If both methods were applied to a patient, data from both 
modalities were included in the analysis. Each patient was exposed to a single episode of 
iHD or at least 48 hours of continuous venovenous hemodiafiltration or both. In the iHD 
group, hemodialysis was applied for 2 to 4 hours depending on the clinical condition of 
patients. Since maintenance iHD is usually performed 3 times a week, 48 hours of CRRT 
was deemed comparable to a single session of iHD.   
 
Laboratory investigations 
In the iHD group, blood samples were obtained immediately before and after the 
hemodialysis session. In the CRRT group, blood samples were taken within 24 hours of 
initiation of CRRT and the second samples were taken 48 hours after collection of the 
first samples.  
Rotational thromboelastometry (ROTEM, ROTEM® delta, Pentapharm GmbH, 
Munich, Germany) was performed to evaluate the impact of RRT on the coagulation 
system. The Extrinsically Activated ROTEM (EXTEM) assay, which focuses on the 
extrinsic coagulation pathway and the Fibrin-based EXTEM (FIBTEM) assay, which 
highlights the fibrinogen function, were performed simultaneously. The clotting time 
(CT), clot formation time (CFT), α angle, maximum clot firmness (MCF), and maximum 
lysis measured parameters were recorded for both assays.  
The impact on platelet function was assessed by electrical impedance aggregometry 

3 
 
with Multiplate® analyzer (Roche, Rotkreuz, Switzerland). To test different pathways of 
platelet aggregation, aggregation was stimulated 1) by arachidonic acid, the substrate of 
cyclooxygenase, which subsequently forms the potent platelet activator thromboxane A2 
(ASPItest), 2) via adenosine-diphosphate (ADP) receptors by ADP (ADPtest). The area 
under the curve (AUC) values which is considered the best parameter to reflect overall 
platelet aggregation of both tests were recorded.  
Platelet count and conventional coagulation tests including prothrombin time (PT), 
activated partial thromboplastin time (aPTT) and fibrinogen assay were performed before 
and after dialysis. The concentration of D-dimer was measured, which reflects 
fibrinolysis-specific degradation. The activity levels of protein C and protein S were also 
measured at two time points. The levels of these vitamin K-dependent anticoagulants 
were compared between pre- and post-dialysis to evaluate the regulation of clot formation. 
 
Study outcomes 
The primary study outcome was changes in CT of EXTEM after dialysis. Secondary 
outcomes included changes in other EXTEM and FIBTEM parameters, AUC of platelet 
aggregometry, platelet count, PT, aPTT, fibrinogen concentration, D-dimer concentration, 
the activity level of protein C and protein S, bleeding events, and transfusion requirements 
after dialysis. Laboratory test results were compared before and after the application of 
each dialysis modality. To identify differences in changes according to dialysis modality, 
a comparison of each study outcome was made between the iHD group and the CRRT 
group. Bleeding events and transfusion requirements within 24 hours after dialysis in the 
iHD group or within 24 hours after the second blood sample collection in the CRRT group 
were also compared between the two groups. The severity of bleeding events were graded 

4 
 
by the modified World Health Organization bleeding scale.  
 
SAP 
Based on a previous study regarding the reproducibility of ROTEM results, the mean 
(± standard deviation) CT of EXTEM was set as 55 ± 6.9 seconds before dialysis. An 
absolute difference of 5 seconds in CT after dialysis was deemed significant. With a two-
sided type-I error of 0.05 and a power of 80%, the required sample size was calculated to 
be 60 patients. Considering a loss to follow-up of 40%, the sample size was increased to 
50 patients in each group, resulting in a total sample size of 100 patients. 
Normally distributed continuous data were described as means and standard 
deviation and non-normal distributed data were described as a median and interquartile 
range [25th–75th interquartile range]. The normality of continuous data was assessed 
through the Shapiro-Wilk test. Comparisons between groups were performed by using the 
Student t-test or the Mann-Whitney U test for the continuous variables normally or non-
normally distributed, respectively. Categorical variables were reported as numbers and 
percentages. Categorical data were compared with a chi-square test. A P value less than 
0.05 was considered statistically significant and statistical analysis was performed using 
IBM SPSS 27.0 (IBM Corp, Armonk, NY, USA).