Acute kidney injury as a risk factor for the development of chronic kidney disease and mortality in hospitalized patients

Abstract Background and Aims Acute kidney injury (AKI) is a complication that affects more than 5% of all hospital admissions and up to one third of patients admitted to critical care units. This entity, whose incidence is on the rise, remains a major cause of morbidity and mortality. In addition, AKI has been linked as an independent risk factor for mortality, especially in severe forms, and of those patients who survive, a percentage will develop chronic kidney disease (CKD) during follow-up. We conducted this study to analyse the incidence of CKD at 6 and 12 months follow-up in hospitalized patients with AKI, to identify possible risk factors leading to its development and to determine mortality in this group of patients. Method This is a retrospective study of a cohort of cases with AKI (baseline eGFR >60 mL/min/1.73 m2 without previous structural damage) from our hospital, taking place from June 2020 to February 2021. Regarding the evolution of the AKI, four possibilities were considered: recovery of normal kidney function, development of CKD at 6 months, development of CKD at 12 months or death during follow-up. Results We studied 148 patients (55% male), with a median age of 83 years (74-87). Thirty-six patients (24.3%) developed CKD at 6 months follow-up and 30 patients (20.3%) at 12 months. Forty-one patients (27.7%) died within the first 12 months following de episode of AKI. The risk factors identified for development of CKD at 12 months were older age (85 vs 77; p = 0.03), higher serum lactate dehydrogenase levels at admission (246 U/L vs 201 U/L; p = 0.04) and at 3 months (252 U/L vs 192,5 U/L; p = 0.039), and eGFR < 60 mL/min/1.73 m2 at 1 week (74,5 vs 57; p = 0.004) and at 3 months (79 vs 50; p < 0.001) of follow-up. Identified risk factors and predictors of AKI-associated mortality were older age (84 vs 80,5; p = 0.018), concomitant oncological pathology (10,8% vs 7,4%; p = 0,018), higher Charlson index (6 vs 5, p <0.001), higher AKI stage (p = 0.042), lower serum albumin levels at first (3.35 g/dL vs 3.90 g/dL; p = 0.014) and at third month (3,2 g/dL vs 4 g/dL; p < 0.001) of follow-up. Conclusion Our study showed a high incidence of CKD in patients who have had an episode of AKI. Several risk factors for development of CKD were identified, being the older age and the greater length of recovery period from AKI the most useful predictors in the clinical practice. AKI-associated mortality was very high in those older patients with higher comorbidity and persistence of AKI. Despite advances, we need non-classical biomarkers for early diagnosis and more effective therapeutic measures to avoid this high prevalence of CKD and mortality.