Abstracts presented at the 26th Annual Congress of the Belgian Society of Internal Medicine, 9-10 December 2022, Dolce La Hulpe, La Hulpe, Belgium

Background Dry weight is defined as the lowest tolerated post-dialysis weight at which there are minimal signs or symptoms of hypovolemia or hypervolemia. Achieving dry weight is a goal for each dialysis session. That improves blood pressure control and reduces cardiovascular risk in dialysis patients. Haemodialysis patients may experience weight loss likely related to a reduction of dry mass when catabolic reactions and inflammation occur. Our aim was to assess the impact of SARSCov-2 infection on haemodialysis patients and analyse factors associated with dry weight variations observed during the COVID-19 pandemic. Method(s): In this retrospective observational single-centre study, we analysed the clinical characteristics of all patients undergoing haemodialysis at the Pole Hospitalier Jolimont during COVID-19 pandemic from 1 March 2020 to 28 February 2022. We determined dry weight at day 1 after diagnosis of SARSCov-2 infection or at day 1 of a randomly assigned 28-days observation period and at 2, 3 and 4 weeks later. We compared infected and uninfected patients and examined the clinical features associated with SARSCov-2 infection and those associated with changes in dry weight. Result(s): Within the observation period, among the 162 haemodialysis patients, 47 patients were infected with SARSCov-2. Three patients were excluded because they have been infected before the first dialysis session and seventeen others due to missing data. Two patients were infected twice but we considered the second episodes as relevant and had therefore 144 observations. Dry weight variation ratio (dry weight variation divided by dry weight at day 1) was a continuous non normally distributed variable for which we performed Wilcoxon rank sum tests and Student's t-tests. Dry weight variations were bigger in patients infected with SARSCov-2 compared to non-infected patients: the mean dry weight variation ratio was - 2,4 +/- 2,2% (SD) in the infected dialysis patients and - 0,6 +/- 2,0% in the uninfected patients (p < 0.001). A very strong association was found between SARSCov-2 infection and loss of dry weight (0,5 kg and more) with odds ratio = 21,89;95% CI [7,17-66,85]. No difference was found whether infected patients were symptomatic or not (-2,6 +/- 2,2% vs - 2,3 +/- 2,3%;p = 0,662). Infected patients and non-infected patients significantly differ by the sex distribution (76% vs 52% males;p = 0,008). We performed a Cochran-Mantel-Haenszel stratified analysis and confirmed the association between loss of dry weight and SARSCov-2 infection after controlling for effect modification or confounding by sex. Furthermore, dry weight often varies during early haemodialysis sessions and a bias such as a short dialysis duration was also ruled out. Indeed, no correlation was found between the shortest dialysis durations (less than 2 months) and the dry weight variations observed in our population. Discussion(s): SARSCov-2 infection is associated with decreases of dry weight in haemodialysis patients. Systemic effects of SARSCov-2 infection are suspected since dry weight changes are quite similar both in symptomatic and asymptomatic infected dialysis patients. Only 2 patients in our population died from complications related to SARSCov-2 infection. Adapting dry weight may be a major element in lowering mortality in infected dialysis patients.