No increase in the incidence of acute kidney injury in a population-based annual temporal trends epidemiology study

Recent literature suggests an increase in the incidence of acute kidney injury (AKI). We evaluated population-based trends of AKI over the course of nine years, using a validated electronic health record tool to detect AKI. All adult residents (18 years of age and older) of Olmsted County, Minnesota (MN), admitted to the Mayo Clinic Hospital between 2006 and 2014 were included. The incidence rate of AKI was calculated and temporal trends in the annual AKI incident rates assessed. During the nine-year study period, 10,283, and 41,847 patients were admitted to the intensive care unit or general ward, with 1,740 and 2,811 developing AKI, respectively. The unadjusted incidence rates were 186 and 287 per 100,000 person years in 2006 and reached 179 and 317 per 100,000 person years in 2014. Following adjustment for age and sex, there was no significant change in the annual AKI incidence rate during the study period with a Relative Risk of 0.99 per year (95% confidence interval 0.97-1.01) for intensive care unit patients and 0.993 per year (0.98-1.01) for the general ward patients. Similar results were obtained when the ICD-9 codes or administrative data for dialysis-requiring AKI was utilized to determine incident cases. Thus, despite the current literature that suggests an epidemic of AKI, we found that after adjusting for age and sex the incidence of AKI in the general population remained relatively stable over the last decade.