Risk factors of mortality in patients with acute kidney injury: Retrospective cohort study with longitudinal follow-up

BACKGROUND: Acute kidney injury (AKI) is a clinical syndrome that, even after recovery of normal renal function, increases the short-term risk of developing chronic kidney disease and may contribute to mortality in hospitalized patients. AIM: To assess patient survival and identify risk factors for mortality. METHODS: We conducted a retrospective cohort study with longitudinal follow-up of patients hospitalized between January 2002 and December 2015, who had an episode of AKI as defined by the Kidney Disease Improving Global Outcomes 2012 guidelines, with return to normal renal function with follow-up extending up to 5 years after discharge, with a median follow-up of 7 years. Patient survival was verified using civil status records and by telephoning patients or their relatives. Risk factors were assessed using univariate and multivariate survival analyses. Short-term mortality was assessed between 3 months and 1 year, medium-term between 1 year and 5 years, and long-term beyond 5 years. RESULTS: A total of 214 patients were included, with mortality data available for 193. Of these, 18 patients (9.3%) died within the short term (mean: 9.22 ± 0.67 months), 18 patients (10.2%) died within the medium term (mean: 36.27 ± 2.73 months), and 26 patients (16.5%) died within the long term (mean: 103.6 ± 6.63 months). The overall mean survival was 159 months. The Kaplan-Meier survival curve showed overall survival rates of 79%, 68%, and 57% at 5 years, 10 years, and 14 years, respectively. Identified mortality risk factors included age over 65, hypertension, diabetes, vascular disease, high Charlson comorbidity index, potassium levels above 5.5 mmol/L, pre-renal AKI, and the short-term development of chronic kidney disease. CONCLUSION: These findings highlight the need to identify patients at higher risk of mortality following an AKI episode.