BackgroundCommunity-acquired acute kidney injury (CA-AKI) is common among hospitalized patients and has a poor prognosis. Research is scarce on the impact of a CA-AKI episode among patients without preexisting kidney disease and has not previously been investigated in Sweden. The aim was to describe the outcomes of patients with normal pre-hospitalization kidney function, admitted with community-acquired AKI and to investigate the association between AKI severity with outcomes.MethodsA retrospective population-based study was applied including patients with CA-AKI according to KDIGO classification, admitted via emergency department (ED) 2017–2019 and with a 90-day follow-up period from the ED-admission, collecting data from the Regional Healthcare Informative Platform. Age, gender and AKI stages, mortality and follow-up regarding recovery and readmission was registered. Hazard ratio (HR) and 95% confidence Interval (CI) for mortality was analyzed using Cox regression adjusted for age, comorbidities, and medication.ResultsThere were 1646 patients included, mean age was 77.5 years. CA-AKI stage 3 occurred in 51% of patients < 65 years of age and 34% among those > 65 years. In this study, 578 (35%) patients died and 233 (22%) recovered their kidney function. Mortality rate peaked within the first two weeks and among those at AKI stage 3. Nephrology referral post discharge occurred in 3% and 29% were readmitted. HRs for mortality was 1.9 (CI 1.38–2.62) for those who are > 65 years, 1.56 (CI 1.30–1.88) for atherosclerotic-cardiovascular disease. Medication with RAASi related to a decreased HR 0.27 (95% CI 0.22–0.33).ConclusionsCA-AKI is associated with high mortality within 90 days, increased risk for developing chronic kidney disease (CKD) and only one fifth recover their kidney function after hospitalization with an AKI. Nephrology referral was sparse. Patient follow-up after a hospitalization with AKI should be carefully planned during the first 90 days and focused on identifying those with a higher risk of developing CKD.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12882-023-03221-2.