A simple method for the calculation of dialysis Kt factor as a quantitative measure of removal efficiency of uremic retention solutes: Applicability to high-dialysate vs low-dialysate volume technologies.

Dialysis urea removal metrics may not translate into proportional removal efficiency of non-urea solutes. We show that the Kt factor (plasma volume totally cleared of any solutes) differentiates removal efficiency of non-urea solutes in different technologies, and can easily be calculated by instant blood-dialysate collections. We performed mass balances of urea, creatinine, phosphorus and beta2-microglobulin by whole dialysate collection in 4 low-flux and 3 high-flux hemodialysis, 2 high-volume post-hemodiafiltration and 7 short-daily dialysis with the NxStage-One system. Instant dialysate/blood determinations were also performed at different times, and Kt was calculated as the product of the D/P ratio by volume of delivered dialysate plus UF. There were significant differences in single session and weekly Kt (whole dialysate and instant calculations) between methodologies, most notably for creatinine, phosphorus and beta2-microglobulin. Urea Kt messured in balance studies was almost equal to that derived from the usual plasma kinetic model-based Daugirdas' equation (eKt/V) and independent V calculation, indicating full correspondence. Non-urea solute Kt as a fraction of urea Kt (i.e. fractional removal relative to urea) showed significant differences between technologies, indicating non-proportional removal of non-urea solutes and urea. Instant Kt was higher than that in full balances, accounting for concentration disequilibrium between arterial and systemic blood, but measured and calculated quantitative solute removal were equal, as were qualitative Kt comparisons between technologies. Thus, we show that urea metrics may not reliably express removal efficiency of non-urea solutes, as indicated by Kt. Kt can easily be measured without whole dialysate collection, allowing to expand the metrics of dialytic efficiency to almost any non-urea solute removed by dialysis

Safety and efficacy of COVID-19 vaccines in patients on dialysis: a multicentre cohort study in Italy

Background The aim of this study was to evaluate the efficacy and safety of COVID-19 vaccines in patients undergoing haemodialysis in Italy compared to the general population.Methods In this cohort study, 118 dialysis centres from 18 Italian Regions participated. Individuals older than 16 years on dialysis treatment for at least 3 months, who provided informed consent were included. We collected demographic and clinical information, as well as data on vaccination status, hospitalisations, access to intensive care units and adverse events. We calculated the incidence, hospitalisation, mortality, and fatality rates in the vaccinated dialysis cohort, adjusted for several covariates. The incidence rates of infection in the dialysis cohort and the general population were compared through Standardised Incidence Rate Ratio.Results The study included 6555 patients vaccinated against SARS-CoV-2 infection according to the schedule recommended in Italy. Between March 2021 and May 2022, there were 1096 cases of SARS-CoV-2 infection, with an incidence rate after completion of the three-dose vaccination cycle of 37.7 cases per 100 person-years. Compared to the general population, we observed a 14% reduction in the risk of infection for patients who received three vaccine doses (Standardised Incidence Rate Ratio: 0.86; 95% Confidence Interval: 0.81-0.91), whereas no statistically significant differences were found for COVID-19-related hospitalisations, intensive care unit admissions or death. No safety signals emerged from the reported adverse events.Conclusions The vaccination program against SARS-CoV-2 in the haemodialysis population showed an effectiveness and safety profile comparable to that seen in the general population