Lesão renal aguda em nonagenários: incidência, preditores e prognóstico

Abstract

Introduction: The aging of the population has increased the frequency with which nephrologists encounter nonagenarians with acute kidney injury (AKI). The management of these patients has peculiarities that even involve bioethical aspects, such as the introduction of renal support therapy (RTR) at this end of life. Objective: to investigate the incidence, predictors and prognosis of AKI in nonagenarians. Methods: We conducted a retrospective cohort study in a tertiary care hospital. Between 2006 and 2016, 832 nonagenarians were admitted to this hospital for two or more days and a random sample of 461 patients was obtained, respecting the sample size calculation. AKI was defined using serum creatinine using the KDIGO (Kidney Disease Improving Global Outcomes) criteria. Results: Of the 461 patients selected, 25 were excluded because they did not have 2 or more creatinines; thus, 436 patients participated in the final analysis. The mean age was 93.5 ± 3.3 years and the incidence of AKI was 45%. Length of hospital stay, intensive care unit (ICU) admission, use of vasoactive drugs (VAD) and mechanical ventilation (MV) were independent risk factors for AKI. Mortality was significantly higher in patients with AKI: 66.8% versus 23.8% in the group without AKI (p<0.001). After multivariate analysis, age, Charlson comorbidity score, use of DVA, MV and KDIGO classification stage remained independent predictors of mortality. Only 13 patients underwent RRT; all of them were in the ICU, using VAD and almost 77% on MV, highlighting the extreme severity of this subgroup. Mortality among dialysis patients was 100% compared to 64% among non-dialysis patients (p=0.008). However, when dialysis patients were compared to a random sample of nonagenarians with AKI matched for severity, there was no difference in mortality (100% x 96%, p=1.0). Conclusion: the incidence of AKI in nonagenarians is very high and accompanied by a poor prognosis. The 100% mortality rate in patients undergoing RRT, composed of critically ill nonagenarians in an intensive care environment, highlights the need for discussion about the usefulness versus futility of this therapy in this population.