COVID-19 AND ACUTE KIDNEY INJURY IN ELDERLY PATIENTS: COMPARATIVE COHORT STUDY BETWEEN THE FIRST AND SECOND WAVES OF THE PANDEMIC IN BRAZIL

In the different waves of the pandemic caused by the SARS-CoV-2 virus, the elderly continued to be affected with more severe disease cases and possible progression to death. Thus, the study sought to compare the incidence of AKI in the elderly during the first and second wave of the pandemic in Brazil and the risk factors associated with its development and death.

Retrospective cohort study that evaluated patients over 60 years admitted to a Public, Tertiary, and Referral Hospital for COVID-19 from March to December/2020 (1st wave) and from January to May/2021 (2nd wave). The patients were followed up until the clinical outcome, and the diagnosis of AKI was made according to the KDIGO 2012 criteria. For statistical analysis, AKI and death were established as dependent variables, using the Chi-Square Test to compare categorical variables and the T-test for continuous variables. Next, multivariate analysis was carried out.

434 elderly patients diagnosed with COVID-19 were admitted, 173 in the first wave and 261 patients in the second wave. These two groups were similar in terms of age (72.41±8.414 vs. 71.48±8.033, p = 0.323), admission to the intensive care unit (56.1 vs. 58.2%, p = 0.655), use of vasoactive drugs ( 43.9 vs. 52.9%, p = 0.068), need for mechanical ventilation – MV – (43.4 vs. 52.5%, p = 0.062), SOFA (8.02 ± 4.07 vs. 7.31 ± 3.55, p = 0.441), the incidence of AKI (56.6 vs. 58.6%, p = 0.684) and mortality (46.8 vs. 55.2%, p = 0.088). However, they differed in terms of white race (77.5 vs. 86.8%, p = 0.011), use of corticosteroids (56.6 vs. 93.9%, p < 0.001), presence of proteinuria (44.8 vs. 58 .2%, p = 0.031), CPK (353.1±705.74 vs. 1228.37±4830.47, p = 0.003), D Dimer (5098±5995.044 vs. 2436.5±8398.381, p = 0.0147), APACHE (19.21±7.53 vs. 17.47±5.64; p = 0.001), and ATN-ISS (0.765±0.236 vs. 0.86±0.213, p = 0.004). The two waves were similar regarding the following factors associated with the development of AKI: baseline creatinine, higher CPK, D-Dimer, SOFA and APACHE values, need for MV, use of vasoactive drugs, presence of proteinuria and hematuria in the urine I on admission to hospital. There was a difference between the waves regarding hypertension (63.89 vs. 77.78%, p = 0.0202), use of ACEI/ARB (42 .59 vs. 56.21%, p 0.0412) and the basal glomerular filtration rate (91±29.616 vs 80.5±26.791, p = 0.0021). In logistic regression, baseline MV and creatinine (OR 10.54, CI 1.22-90.61, p = 0.032) remained a factor associated with AKI in the first wave; while in the second, in addition to MV, SAH (OR 1.646, CI 1.150-1.839, p = 0.018), HTU (OR 1.681, CI 1.124-1.822, p = 0.018) and D Dimer (OR 1.977, CI 2.000-2.003, p = 0.023). CPK (OR 1.009, CI 1.001-1.017, p = 0.042) and MV (OR 17.71, CI 1.13-277.62, p = 0.002) were identified as factors associated with mortality in the first wave, as well as DM (OR 4.875 CI 2.602-7.094, p = 0.001), AKI (OR 1.858, CI 1.070-1.287, p < 0.001), need for dialysis (OR 1.813, CI 1.086-1.407, p < 0.001), PTU (OR 1.968, CI 1.142-1.913, p = 0.032) and ATN-ISS (OR 5865.316, CI 1.325-25967740, p = 0.043) in the second wave. When comparing the two waves, the factors that remained as differentials between the waves in the logistic regression were the ATN-ISS (OR 213.384, CI 14.748-3087.459, p < 0.001) and APACHE (OR 0.928, CI 0.880-0.977, p = 0.005).

The incidence of AKI was similar between the two waves of the pandemic; however, its severity was higher in the second wave, and this factor was associated with death. Despite the greater severity of AKI, evidenced by the higher ATN-ISS and greater severity of cases – observed by the larger APACHE values, there was no more mortality of patients during the second wave of the pandemic.