#3498 LONG-COVID IN PATIENTS ON HEMODIALYSIS: A SINGLE CENTER ANALYSIS
Authors: Trigo Ana , Ramos Ana Rita , Duarte Rui , Sofia Flora , Lopes Karina , Santos Paulo 
Published: June 2023

Abstract

Background and Aims
It is known that maintenance hemodialysis (MHD) patients have a high risk of initial mortality from COVID-19. Concurrently, the Post-COVID-19 Syndrome also appears to be highly prevalent between them. However, in the general population, it looks like the probability of having long covid symptoms has been decreasing after covid-19 vaccination. As the number of vaccinated MHD patients against SARS-CoV-2 is currently extremely high in Portugal, with this study we aimed to investigate the current prevalence of long-COVID in our MHD patients and to identify if their baseline characteristics served as a predictor to this syndrome.

Method
In this retrospective single center study, we questioned 71 MHD patients regarding the history of COVID-19, its symptoms when it first appeared, and the symptoms that persisted at least 12 weeks after the onset of the disease. All patients were in our MHD program for at least 3 months before SARS-CoV-2 infection. Patients with COVID-19 were divided between those with and without long-COVID (long-COVID was defined as the existence of symptoms that persisted for more than 12 weeks). Baseline characteristics (sex, age, Chalson Comorbidity Index (CCI), time since the beginning of dialysis, diabetes, hypertension, hospitalization, the use of corticosteroids and the number of vaccines taken) and analytical values (hemoglobin, ferritin, phosphorus and albumin) were statistically evaluated.

Results
From the 71 analyzed MHD patients of the program of Centro Hospitalar do Médio Tejo - Portugal, 27 had a positive Polymerase Chain Reaction (PCR) test for COVID-19. Of those, the mean age was 73,81 years old (±11,08), 63% (n=17) were male and they were on a MHD program for an average of 36,48 (±32,1) months. 25,0% (n=7) of the COVID-19 patients suffered from long-COVID and 48,1% (n=13) had three doses of a vaccine against SARS-CoV-2 at the time of diagnosis. The mean follow up time was 12,59 (±7,11). The most common symptoms were asthenia, cough and sicca syndrome (all present in 14,8% of long-COVID patients), followed by arthralgias and anxiety (both present in 11,1% of the patients). A Receiver Operating Characteristic (ROC) curve was generated plotting sensitivity (y- axis) as a function of 1-specificity (x-axis), which allowed us to conclude that patients didn't have any analytic change that was predictor of long covid when compared to patients without long covid (p values all &gt; 0,05). Regarding to the baseline characteristics of the patients, there was no correlation between sex, age, CCI, time since the beginning of dialysis, diabetes, hypertension, hospitalization, the use of corticosteroids, the number of vaccines taken and the manifestation of long COVID (according to Fisher's Exact test). There was a statistically significant association with the presence of long covid and the initial symptoms of COVID-19 disease (with a p value of 0,01 and with a moderate strength - Cramer's V of 0,57).

Conclusion
Our study showed a moderate prevalence of COVID-19 infection and a low prevalence of long COVID in MHD patients. Besides there was no correlation between the number of vaccine doses and the presence of long COVID, one can only assume that the low incidence of post-COVID-19 syndrome is due to the vaccination. Even so, more studies with a higher number of patients and without memory bias are needed to prove a lower incidence of this syndrome after the massive vaccination. The fact that the higher number of initial symptoms correlate with long-COVID also leads to state that very symptomatic patients must remain under close monitoring.