Predictive role of estimated glomerular filtration rate prior to surgery in postsurgical acute kidney injury among very elderly patients: a retrospective cohort study

Background: Acute kidney injury (AKI) is a common complication after surgery. Because of unpredictable and variable age-dependent physical decline, the incidence, risk factor of postsurgical AKI and the predictive power of estimated glomerular filtration rate prior to surgery (eGFRpreSurg) has not been fully elucidated in very elderly patients. Methods: All discharged patients aged ≥80 years without chronic kidney disease who underwent surgery prior to intensive care unit (ICU) admission from 2017 through 2018 were included. Clinical, biological and surgical data were recorded. Mean of outpatient creatinine values from the year prior to ICU admission was used as the baseline value to determine the occurrence of AKI. Postoperative AKI was diagnosed according to Kidney Disease Improving Global Outcomes criteria. Results: Among 243 very elderly postoperative patients admitted during the study period, 48 had AKI during their ICU stay. The occurrence of postsurgical AKI was associated with longer ventilation times (p < .001) and higher mortality (p < .001). The eGFRpreSurg, which is calculated based on the Modification of Diet in Renal Disease study equation, was a risk factor for postoperative AKI (OR = 2.662, p = .010). The incidence of postoperative AKI was significantly higher among patients with lower eGFRpreSurg than among those with an eGFRpreSurg ≥ 70 mL/min/1.73 m(2) (p = .003). Conclusion: Postsurgical AKI in very elderly patients has a high incidence and is a risk factor for mortality. Our study confirmed that eGFRpreSurg could be used as an index for AKI risk stratification.