(28) Kidney Function Before and After Acute Kidney Injury: A Nationwide Population-Based Cohort Study

Sunday, August 28, 2022

8:00 AM – 1:45 PM CEST

Location: Hall C

Publication Number: 1073

Presenting Author(s)

Simon K. Jensen, MD, PhD
– Epidemiologist, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Aarhus, Denmark, Department of Clinical Epidemiology, Aarhus University, Aarhus, Midtjylland, Denmark

Co-Author(s)

Uffe Heide-Jørgensen
– Aarhus N, Midtjylland, Denmark
Søren Vestergaard, MD
– Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Midtjylland, Denmark
Henrik Gammelager
– Department of Intensive Care Medicine, Aarhus University Hospital, Aarhus, Denmark, Denmark
Henrik Birn
– Department of Clinical Medicine, Aarhus University, Denmark, Denmark
Dorothea Nitsch
– Professor, Department of Non-communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, United Kingdom
Christian Christiansen, MD,PhD
– Professor, Consultant, Department of Clinical Epidemiology, Aarhus University and Aarhus University Hospital, Aarhus, Denmark, Aarhus N, Midtjylland, Denmark

Background: In healthy adults, estimated glomerular filtration rate (eGFR) is stable until approximately 40 years of age after which it declines by ~1 ml/min/year. Consequently, the risk of developing chronic kidney disease (CKD), which is defined as an eGFR < 60 ml/min/1.73m2, increases with age. Another risk factor for CKD is acute kidney injury (AKI), which is defined by an abrupt decline in kidney function often related to treatment with nephrotoxic drugs. Intriguingly, even if AKI is transient and kidney function recovers, it increases the risk of developing CKD. This could be reflected by a drop in eGFR level, a decrease in eGFR slope, or a combination of both. However, data describing the changes in eGFR level or eGFR slope from before to after AKI are sparse and conflicting.

Objectives: To describe changes in eGFR level and eGFR slope from before to after first-time AKI in individuals with repeated measurements before and after AKI.

Methods: Using Danish population-based laboratory databases linked with health and administrative databases, we included individuals with first-time AKI defined by an acute increase in plasma creatinine (pCr) during 2010 to 2017. We restricted the population to individuals with an outpatient baseline eGFR 8-365 days before AKI and three or more outpatient pCr measurements both before and after AKI. Individuals were stratified by baseline eGFR (≥/ < 60 ml/min/1.73m2) and linear regression models were used to estimate and compare individual eGFR slopes and eGFR levels before and after AKI.

Results: We identified 265,161 individuals with first-time AKI. Of these 98,072 individuals had an outpatient baseline eGFR and three or more pCr measurements both before and after AKI and were included for further analyses. Included individuals were younger and had a substantially lower one-year mortality compared with individuals not included. Among included individuals with AKI, 64,805 (66%) had a baseline eGFR ≥60 ml/min/1.73m2 and 33,267 (34%) had a baseline eGFR < 60 ml/min/1.73m2. In individuals with a baseline eGFR ≥60 ml/min/1.73m2, AKI was associated with a median difference in eGFR level of −5.6 ml/min/1.73m2 (interquartile range [IQR], −16.1 to 1.8) and a median difference in eGFR slope of −0.4 ml/min/1.73m2/year (IQR, −5.5 to 4.4). Correspondingly, among individuals with AKI and a baseline eGFR < 60 ml/min/1.73m2, first-time AKI was associated with a median difference in eGFR level of −2.2 ml/min/1.73m2 (IQR, −9.2 to 4.3) and a median difference in eGFR slope of 1.5 ml/min/1.73m2/year (IQR, −2.9 to 6.5).

Conclusions: In individuals with repeated measurements before and after AKI, first-time AKI was associated with changes in both eGFR level and eGFR slope for which the magnitude and direction depend on baseline eGFR.