Mortality and costs associated with acute kidney injury following major elective, non-cardiac surgery

Abstract

ObjectiveThis study evaluated postoperative AKI severity and its relation to short- and long-term patient outcomes. DesignA retrospective, single-center cohort study of patients undergoing surgery from January 2015 to May 2020. SettingAn urban, academic medical center. PatientsAdult patients undergoing elective, non-cardiac surgery at our institution with a postoperative length of stay (LOS) of at least 24 h were included. Patients were included in 1-year mortality analysis if their procedure occurred prior to June 2019. InterventionsNone. MeasurementsPostoperative AKI was identified and staged using the Kidney Disease Improving Global Outcomes definitions. The outcomes analyzed were in-hospital mortality, LOS, total cost of the surgical hospitalization, and 1-year mortality. Main resultsOf the 8887 patients studied, 648 (7.3%) had postoperative AKI. AKI was associated with severity-dependent increases in all outcomes studied. Patients with AKI had rates of in-hospital mortality of 2.0%, 3.8%, and 12.5% for stage 1, 2, and 3 AKI compared to 0.3% for patients without AKI. Mean total costs of the surgical hospitalization were $23,896 (SD $23,736) for patients without AKI compared to $33,042 (SD $27,115), $39,133 (SD $34,006), and $73,216 ($82,290) for patients with stage 1, 2, and 3 AKI, respectively. In the 6729 patients who met inclusion for 1-year mortality analysis, AKI was also associated with 1-year mortality rates of 13.9%, 19.4%, and 22.7% compared to 5.2% for patients without AKI. In multivariate models, stage 1 AKI patients still had a higher probability of 1-year mortality (OR 1.9, 95% CI 1.3–2.6, p < 0.001) in addition to $4391 of additional costs when compared to patients without AKI (95% CI $2498–$6285, p < 0.001). ConclusionsAll stages of postoperative AKI were associated with increased LOS, surgical hospitalization costs, in-hospital mortality, and 1-year mortality. These findings suggest that patients with even a low-grade or stage 1 AKI are at higher risk for short- and long-term complications.