MO878: Does Haemodiafiltration Versus Haemodialysis Have Clinical Benefits for Covid-19 Severity and Mortality in Maintenance Haemodialysis Patients?
Authors: Stepanova Natalia , Rysyev Andriy , Rusyn Oksana , Snisar Lyudmyla , Chernianu Darya , Khyzhuna Anna , Belousova Olga , Kompaniets Olga 
Published: May 2022

Abstract

BACKGROUND AND AIMS
It has been demonstrated that online haemodiafiltration (HDF) provides higher clearance of middle molecular solutes compared with high-flux haemodialysis (HD) due to its convective component and may improve clinical outcomes in maintenance haemodialysis patients. However, the clinical superiority of HDF compared with standard HD is still controversial. Moreover, there is a general lack of these data on the current topic in patients infected with COVID-19. The present study aimed to prospectively analyze whether HDF has benefits for COVID-19 severity and mortality in maintenance haemodialysis patients.

METHOD
A total of 340 maintenance haemodialysis patients aged 53.5 ± 12.9 years and a median dialysis vintage of 40 (24–74) months were included in this prospective multicentre cohort study conducted across 5 dialysis centers. All patients were not infected with COVD-19 at the time of the enrollment and subsequently followed up from March 2020 to September 2021 (the mean duration was 7 (4.2–15.4) months). The study outcomes were COVID-19-associated hospitalization needs due to supplemental oxygen requirements and COVID-19-associated mortality.
The data were presented as the mean and the standard deviation (M ± SD) or the median and the interquartile ranges [Me (Q25–Q75)] and compared using the Student's t-test or the Mann–Whitney U-test as appropriate. The Chi-squared test was used to determine the differences between categorical variables. The univariate logistic regression analyses were performed to evaluate the predictive factors for COVID-19-associated severity and mortality. Then, the Cox proportional-hazards regression model was carried out using the factors found to be significant by the univariate analysis.

RESULTS
Among the enrolled patients, there were 312 (91.7%) patients on HDF and 28 (8.3%) patients treated with HD. Sex (χ2 = 1.12 P = 0.29), age (55.3 ± 12.9 versus 59.6 ± 12.5 years; P = 0.07) and dialysis vintage [40 (23–72) versus 45 (29–84) months; P = 0.39] did not differ between the HDF and the HD groups at the study entry. During the follow-up period, 98 out of 312 (31.4%) of the HDF patients and 16 out of 28 (57.1%) of the HD patients were infected with COVID-19 (χ2 = 9.6; P = 0.001). Among them, there were 54 out of 98 (55.1%) of the HDF patients and 12 out of 16 (75%) of the HD patients who required hospitalization with oxygen supplementation (χ2 = 12.6; P = 0.0004). Out of 98, 4 (4.1%) of the HDF patients and 5 out of 16 (31.2%) of the HD patients died (χ2 = 31.3, P &lt; 0.0001) during the follow-up period. In the univariate logistic regression analysis, older patient age {OR: 1.03, [95% confidence interval (95% CI) 1.01–1.05]}, diabetic status (OR: 2.8, 95% CI 1.4–5.5), long dialysis vintage (OR: 1.07, 95% CI 1.03–1.1), low blood flow (OR: 1.04, 95% CI 1.02–1.08) and HD treatment (OR: 4.1, 95% CI 1.5–11.2) were significantly associated with the requirement of oxygen supplementation. In the Cox regression model adjusted for all mentioned factors, HD treatment was significantly associated with COVID-19 severity and oxygen requirement (Figure 1). However, when we performed the same model to predict COVID-associated mortality, HD treatment lost its significance, and only patient age (P = 0.02) and dialysis vintage (P = 0.004) were significantly associated with reduced survival.

CONCLUSION
The HDF patients required fewer hospitalizations and oxygen support and had a lower mortality rate compared with the HD patients. Although HDF treatment versus HD treatment was significantly associated with better COVID-19 outcomes in our cohort, a predictive conclusion of the study was limited by the small sample size of the HD group and a relatively short follow-up period. Further large-scale studies are needed to determine the role of HDF versus HD in COVID-19-associated severity and mortality in maintenance haemodialysis patients.