DISCUSSION
Our analysis confirmed that the risk group for a severe course of COVID-19 infection, as well as for death, are patients over 59 years, diabetes mellitus was found to be an independent risk factor for hospital admission. Our data correspond with the conclusions of the ERACODA register in which a 28-day mortality was primarily associated with elderly kidney transplant patients (5). An analysis by French authors comparing the course of COVID-19 infection in patients after kidney transplantation with a non-transplant group also confirmed the significantly worse outcome of COVID-19 in the group of transplant patients over 60 years of age (19). Diabetes mellitus was confirmed as an independent risk factor for a serious course of COVID-19 in the group of patients after kidney transplantation (21). Advanced impairment of graft function at the time of infection was identified as another risk factor for poor outcome in the studied group of patients. The prevalence of the alpha variant in Slovakia did not affect the development of morbidity and mortality in patients after kidney transplantation.
The pandemic heavily impacted both the dialysis care and organ procurement and transplantation activities: hemodialysis centers became a source of infections owing to the model of repetitive treatment in a closed community; peritoneal dialysis insertions which could have protected CKD patients as they allow dialysis outside the hospital were postponed as non-urgent procedures (4, 15).
These factors also affected the situation in Slovakia. A quick understanding that restricting or stopping kidney transplants from deceased and living donors could lead to unnecessary deaths of the waitlisted patients led to setting the rules so that the procurement and transplantation program in Slovakia did not stop during the second wave of the COVID-19 crisis. Claims that transplant patients are at a high risk of infection and it is better to keep them on the hemodialysis program have proved to be unsubstantiated. All the more so, given that the morbidity and mortality of patients in hemodialysis centers in Slovakia was 52% and 30%, which was a higher rate compared to the ERA-EDTA Registry (7) and the ERACODA database (5) data, where 28-day mortality was 19.9% and 25%. The onset of morbidity and mortality in Slovakia during the second wave of the COVID-19 pandemic was also reflected in the increase in the number of infected KTRs, but compared to the hemodialysis population, the risk of infection and death was 3.7 times lower. According to the data of ERA-EDTA a EU National Competent Authorities on Organ donation and transplantation the risk of being infected by SARS-CoV-2 was more than 4 times lower for kidney transplant recipients than for hemodialysis patients, mainly because transplant patients can be managed at home, while hemodialysis still takes place mostly in hospital settings (4, 17). It should be noted that hemodialysis patients are generally older and have a higher prevalence of comorbid conditions than kidney transplant recipients (16). At the Slovak hemodialysis units, screening for COVID-19 was performed not only in symptomatic patients and as a post-contact screening, but also as a part of routine surveillance, whereas transplant patients only underwent testing when they presented with symptoms or after the contact with a positive person. On the other hand, lower morbidity and mortality among transplant patients may be explained by better habits to protect oneself from infection and by better opportunities to manage the treatment at home and remotely during the critical period of the pandemic (telemedicine, e-prescription), while hemodialysis still mostly takes place in hospital settings. Therefore, promoting transplantation is integral to fostering future preparedness for other mass infectious disease emergencies (4).
Unlike the first wave, the second wave in Slovakia was marked by slow enacting of the precautions, greater benevolence, misinterpretation of negative test results (as being a ”freedom pass”) and also pandemic fatigue. Nevertheless, Slovakia was able to maintain the procurement and transplantation program. While donation and organ transplants in some European Union countries dropped by more than 80% (7), in Slovakia it was only up to 33.5%. Kidney transplants from living donors, with the exception of the first wave, continued without restriction and at the same level as in 2018 and 2019. No transmission of infection from the donor to the recipient or infection in the hospital during the short post-transplant period was observed. The first wave of the COVID-19 pandemic in Slovakia has shown that clear rules and strict anti-epidemic measures and their observance by kidney transplant patients as well as their family members are an efficient way to protect against the disease. Increased vigilance during a pandemic and the prevention of infectious diseases should be maintained not only shortly after transplantation, but also later, as patients being longer post-transplantation became infected more frequently (median: 5.7 years).
In January 2021, vaccination started in Slovakia for health professionals and at-risk groups of the population, including patients with CKD, especially patients on dialysis and transplant patients.
The limitation of our analysis lies in the absence of data regarding the treatment of patients during hospitalization, since the patients were not hospitalised in a specialized COVID-19 center, consultation timing varied and thus, the treatment data would not be homogeneous. On the other hand, our analysis deals with the risk factors for a severe course of COVID-19 before the infection onset.