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COVID-19 generated at least 700 million infections in the world. Among survivors, many have long-term cardiovascular, pulmonary, neurological, and cognitive sequelae. Acute kidney injury (AKI) associated with COVID-19 presents a complex physio-pathogenesis, affecting kidney function through different mechanisms (including direct tissue viral invasion), producing tubulo-interstitial, glomerular and/or vascular damage. The incidence among hospitalized patients was 17% (although in some series it was up to 80%). Recent studies warn that there are also long-term kidney consequences in these patients.
Our group previously published the incidence, risk factors and impact of AKI in patients hospitalized with COVID-19 between March and October 2020, in two hospitals in the City of Córdoba, Argentina. The objective of this new study was to evaluate the long-term evolution of eGFR in the subjects included in the previous study who had presented COVID-19-associated AKI.
A retrospective cohort study was carried out. All patients from the previous study who had developed COVID-19-associated AKI during their hospitalization and who survived were included. They were followed for 2 years after hospital discharge. Serum creatinine levels were recorded and eGFR was calculated using CKD-EPI 2009 at different times during follow-up. CKD was defined as an eGFR <60 ml/min/1.73 m2 and AKI according to KDIGO. To calculate the annual drop in eGFR, the following formula was used = (last eGFR during post-discharge follow-up – eGFR at the time of hospital discharge) * 12 months/months of follow-up.
Of the 448 patients included in the original study, 85 had AKI and of those, 45 survived to discharge (32 had AKI I, 10 AKI-II, and 3 AKI-III). The evolution of eGFR expressed as median (interquartile range) at the previous moment (baseline), extreme value during AKI, at the time of hospital discharge, at 3, 6, 12 and 24 months after discharge, was 64. 5 (52.4-77.6); 37.5 (22.8-47.8); 71.9 (48.6-89.7); 65.6 (39.2-89.6); 57.8 (42.9-67.1); 57.2 (42.4-71.9) and 54.2 (41.3-68.9) ml/min/1.73 m2, respectively (Figure 1). That is, there was a recovery in baseline eGFR at the time of discharge, but then there was a progressive and statistically significant decrease at 6, 12 and 24 months of follow-up, compared to baseline values (p<0.05). Taking into account only the control period with the largest number of subjects (22 patients at 12 months), there was a clear trend towards an increase in CKD, from 40.9% (9/22) to 59.1% (13/22). 22), (p=0.125). Taking into account only the 27 patients in whom serum creatinine was measured at hospital discharge and at least 1 subsequent follow-up, the average annual drop in eGFR was -8.2 ml/min/1.73 m2 (CI 95% = -12.3 to -4.1).
In this study, a follow-up control group was not included, but it can be seen that the loss of eGFR over time is much greater than the loss of average annual eGFR of the general population. There was a significant worsening of eGFR at 6, 12, and 24 months after COVID-19-associated AKI and an accelerated annual decline in eGFR in these patients. These data highlight the importance of including this group of patients in subsequent follow-up and warn of a possible increase in the appearance of CKD due to the high rate of infections worldwide.