#1066 Unobvious long-term effects of COVID-19 for kidneys

Background and Aims The impact of COVID-19 on the chronic kidney disease (CKD) has already been confirmed by researchers around the world. However, there is still no description of this infection influence on kidney function without signs of CKD before it. Method The study included 359 patients from the Moscow region who applied to the nephrologist of the first level regional center in 2022, 154 men and 205 women, mean age 59±16 years. Among the patients who applied for the past year, there were 70 patients with a previously confirmed diagnosis of CKD and 289 who first applied to a nephrologist and had no nephrology complaints, clinical or laboratory signs of CKD before. Results A total of 95 patients from both groups had COVID-19 in 2020-2022 before a visit to a nephrologist, 45 people from the group with CKD (47.4%) and 50 people (52.6%) who were not diagnosed with CKD before COVID-19. 20.4% had COVID-19 earlier than 2 months ago, 6.4% - from 2 to 6 months ago, 45.3% - from 6 to 12 months ago, 27.9% from 12 to 24 months ago. A mild degree of COVID-19 was in 49.4% of patients, moderate - 43, 3%, heavy - 7.3%. It is important to note that 48 patients (96%) who first contacted a nephrologist after COVID-19 were diagnosed with CKD (CKD stages 1-2 - 14 patients (29.17%), 3A and 3B stages - 24 patients (50%), 4 and 5 stages - 10 patients (20.83%)). Relative risk of stage 3+ CKD after COVID-19: RR= 1.036 [95% CI 0.8961 to 1.170], p=0.6742, relative risk of stage 5 CKD: RR= 0.7164 [95% CI 0.3259 to 1.534], p= 0.5403. Thus, the development of advanced (3+) stages of CKD cannot be directly related to past COVID-19. However, if we consider the risk of developing advanced stages of CKD for patients who have experienced moderate to severe COVID-19, then the relative risk of stage 3+ CKD: RR= 1.082 [95% CI 0.8936 to 1.236], p= 0.4607, and relative risk of stage 5 CKD RR = 1.013 [95% CI 0.4134 to 2.341], p>0.9999. Conclusion Unfortunately, it is not possible to link the risk of developing CKD in patients after COVID-19 with the timing after COVID-19 at this stage of the study. In addition, the relationship between COVID-19 and CKD stage cannot be assessed without taking about the structure of CKD causes in both groups. Obviously, a larger and deeper study of this issue is needed, possibly with more patients and long-term monitoring of the dynamics of renal function in patients of both groups.