Incidence, time trends and predictors of acute kidney injury in the region of Stockholm, Sweden.

Acute kidney injury (AKI) is a common and potentially serious complication, yet population-level data on its burden and determinants remain limited. We quantified AKI incidence, temporal trends, and risk factors across a complete healthcare system. We conducted a population-based cohort study including all adult residents of Stockholm, Sweden (2017-2021) using the SCREAM project. AKI events requiring hospitalization or occurring during hospital stays were identified using a composite algorithm incorporating laboratory-based KDIGO creatinine criteria, ICD-10 diagnoses, and acute dialysis procedure codes. We calculated annual incidence rates, temporal trends using Poisson regression, and incidence rate ratios for selected demographic, clinical, and laboratory-defined risk factors. Among approximately 1.9 million adults annually, 0.6-0.7% experienced AKI each year (71-95 per 10,000 person-years). AKI occurred in 5.8-7.8% of hospitalizations, with only 30% reaching KDIGO stage 2-3. From 2017 to 2021, AKI incidence increased by 26% (95% CI 1.23-1.29). Populations at highest risk of AKI were largely consistent over the years, and included older adults, men, and individuals with uncontrolled diabetes, prior AKI, hypertension, heart failure, kidney transplantation, and multiple myeloma. Lower eGFR and higher albuminuria were associated with markedly higher AKI risk in a graded manner. COVID-19 infection was associated with a six-fold higher AKI risk in 2020, but marked attenuation in 2021 suggests it does not explain the overall upward trend. This region-wide analysis quantifies the contemporary burden of AKI and identifies high-risk populations that may benefit from targeted prevention and monitoring strategies.