Medium Cut-Off Dialysis Membranes: Can They Have Impact on Outcome of COVID-19 Hemodialysis Patients?

Immune responses of patients on maintenance hemodialysis after infection by SARS-CoV-2: a prospective observational cohort study

BACKGROUND

Immune dysregulation in patients with acute COVID-19 under chronic hemodialysis (CHD) is fully not elucidated. The changes of mononuclear counts and mediators before and after HD and associations with final outcome were studied.

METHOD

In this prospective study, hospitalized patients with moderate-to-severe COVID-19 under CHD and matched comparators under HD were analyzed for their absolute counts of lymphoid cells and circulating inflammatory mediators. Blood samples were collected before start and at the end of the first HD session; dialysate samples were also collected.

RESULT

Fifty-nine patients with acute COVID-19 under CHD and 20 uninfected comparators under CHD were enrolled. Circulating concentrations of tumor necrosis factor-alpha (TNFα), interleukin (IL)-10, interferon-γ and platelet-derived growth factor-A were increased in patients. Concentrations of mediators did not differ before and after HD. Significant decreases of CD4-lymphocytes and CD19-lymphocytes were found in patients. The decrease of the expression of HLA-DR on CD14-monocytes was associated with unfavorable outcome (defined as WHO-CPS 6 or more by day 28); increased counts of CD19-lymphocytes were associated with better outcomes.

CONCLUSION

Patients under CHD develop an inflammatory reaction to SARS-CoV-2 characterized by increase of inflammatory mediators, decrease of circulating T-lymphocytes and decrease of the expression of HLA-DR on CD14-monocytes.

Medium Cut-Off versus Low-Flux Dialyzers in Hemodialysis Patients with COVID-19: Clinical Outcomes and Reduction in Interleukin-6

INTRODUCTION

The coronavirus disease 2019 (COVID-19) pandemic has caused extensive morbidity and mortality worldwide. Hemodialysis (HD) patients are both vulnerable to COVID-19 infection and tend to suffer greater disease severity and mortality. This retrospective study aimed to compare medium cut-off (MCO) and low-flux (LF) membrane dialyzers in terms of interleukin-6 (IL-6) reduction, change in inflammatory state, intradialytic complications, and mortality in chronic HD patients with COVID-19.

METHOD

HD patients with a confirmed COVID-19 infection were admitted to the hospital for 10-14 days and underwent HD at the COVID-HD unit. Choice of dialyzer membrane used (MCO vs. LF) depended on the primary nephrologist(s). We collected data on demographics, baseline characteristics, laboratory results, diagnosis, treatments, HD prescription, hemodynamic status during HD, and mortality at 14 and 28 days after.

RESULTS

IL-6 reduction ratio (RR) in the MCO group was 9.7 (interquartile range, 71.1) percent, which was significantly higher than that of the LF group (RR, -45.7 [interquartile range, 70.2] percent). The incidence rate of intradialytic hypotension in the MCO group was 3.846 events per 100 dialysis hours (95% confidence interval [CI], 1.954-6.856), which was significantly lower than that of the LF group (9.057; 95% CI, 5.592-13.170). Overall, mortality was not significantly different between the two groups.

CONCLUSION

The MCO membrane was more effective in removing IL-6 and was better tolerated than the LF membrane. Large, randomized controlled trials are required to confirm the relative benefits of the MCO membrane, especially mortality. However, due to the COVID-19 pandemic, our results suggest that the MCO membrane may be beneficial in chronic HD patients with COVID-19.

Arteriovenous fistula as the vascular access contributes to better survival of hemodialysis patients with COVID-19 infection

BACKGROUND

While COVID-19 in chronic hemodialysis patients has high mortality and the pandemic will not end in the near future, effective follow up strategies should be implemented for these patients. Surgeries have been triaged according to their level of urgencies and arteriovenous fistula (AVF) operations were among elective surgeries. This study aimed to analyze the effect of vascular access on the outcomes of hemodialysis patients who had COVID-19.

METHODS

One hundred four hemodialysis patients who had COVID-19 were retrospectively analyzed. Seventy-two of them had AVF as the vascular access while 32 of them had tunneled catheters. Inflammatory markers and outcomes of patients with AVFs and catheters were compared. A logistic regression analysis was performed in order to define factors that contribute to better outcomes in hemodialysis patients.

RESULTS

COVID-19 had high mortality rate in hemodialysis patients (36.5%). Patients with catheters have higher peak ferritin levels (p = 0.02) and longer hospital stay (p = 0.00). Having AVF as the vascular access (OR = 3.36; 95% CI: 1.05-10.72; p = 0.041) and using medium cut-off dialyzers (OR = 7.99; 95% CI: 1.53-41.65; p = 0.014) were related to higher survival of the patients. COVID severity was inversely proportional to the survival (p = 0.000).

CONCLUSIONS

AVFs contribute to higher survival of hemodialysis patients with COVID-19. Even in the pandemic era, end stage renal disease patients should be given the opportunity to have their vascular access properly created.

Anti-Inflammatory Approach in Chronic Dialysis Patients with SARS-CoV-2: ATA or PMMA Dialyzers?

INTRODUCTION

High-flux hemodialysis membranes may modulate the cytokine storm of SARS-CoV-2, but their impact on chronic hemodialysis (CHD) patients is unknown. The aim of the study was the evaluation of asymmetric cellulose triacetate (ATA) and polymethylmethacrylate (PMMA) dialyzers on inflammatory markers and clinical outcomes in CHD patients with SARS-CoV-2.

METHODS

A prospective, observational study on CHD patients with SARS-CoV-2 was carried out. Patients were enrolled from March 2020 to May 2021. Pre- and postdialysis C-reactive protein (CRP), procalcitonin (PCT), and interleukin-6 (IL-6) were determined at each session. Patients who underwent on-line hemodiafiltration (OLHDF) with a PMMA dialyzer were compared with those treated with OLHDF with a ATA dialyzer. The primary endpoint was the differences in the reduction ratio per session (RR) of CRP, PCT, IL-6, and IL-6 RR >25%.

RESULTS

We consecutively enrolled 74 CHD patients with COVID-19, 48 were treated with ATA membrane, and 26 with PMMA. Median IL-6 RR was higher in the ATA group compared to PMMA (17.08%, IQR -9.0 to 40.0 vs. 2.95%, IQR -34.63 to 27.32). Median CRP RR was 7.77% (IQR 2.47-13.77) in the ATA group versus 4.8% (IQR -2.65 to 11.38) in the PMMA group (p = 0.0017). Median PCT-RR% was 77.38% (IQR 70.92-82.97) in ATA group versus 54.59% (IQR 42.62-63.16) in the PMMA group (p < 0.0001). A multiple logistic regression analysis with IL-6 RR >25% as the outcome including the membrane employed, pre-dialysis IL-6, CRP, PCT, and ferritin showed that ATA led to a higher probability to reach the outcome (OR 1.891, 95% CI 1.273-2.840, p = 0.0018) while higher CRP favors the risk of lower IL-6 RR values (OR 0.910, 95% CI 0.868-0.949, p ≤ 0.0001).

CONCLUSIONS

In SARS-CoV-2 CHD patients treated with OLHDF, ATA showed a better anti-inflammatory profile, regarding IL-6 RR, compared to PMMA.

Effects of Different Dialysis Strategies on Inflammatory Cytokine Profile in Maintenance Hemodialysis Patients with COVID-19: A Randomized Trial

Uncontrolled inflammation plays a relevant role in the pathogenesis of coronavirus disease-19 (COVID-19). Here, we studied the time trend of inflammatory markers in a population of hemodialysis (HD) patients affected by COVID-19, undergoing two different dialysis approaches. In a prospective study, thirty-one maintenance HD patients with COVID-19 were randomized to expanded HD (HDx), performed using a medium cut-off membrane, or standard treatment using a protein-leaking dialyzer (PLD). Circulating levels of interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), soluble TLR4 (sTLR4), and interferon-gamma (IFN-γ), were collected at diagnosis, and one and two weeks after. Compared with 14 non-infected HD patients, COVID-19 patients showed lymphopenia and higher ferritin and lactate dehydrogenase levels. Moreover, COVID-19 patients had higher levels of IL-10 (15.2 (12.5) vs. 1.2 (1.4) pg/mL, p = 0.02). Twenty-nine patients were randomized to HDx (n = 15) or PLD (n = 14). After a single treatment, IL-8 showed a significant reduction in both groups, whereas IL-10 decreased only in HDx. All over the study, there were no significant modifications in circulating cytokine levels between the two groups, except for a parallel increase of IL-8 and IL-10 at one week control in the HDx group. No correlations were found between cytokine levels and clinical outcomes. In maintenance HD patients, COVID-19 is not related to a sustained inflammatory response. Therefore, modulation of inflammation seems not to be a suitable therapeutic target in this specific population.