Amino acid infusion and acute kidney injury after aortic surgery: a multicenter observational study with target trial emulation.

Acute kidney injury (AKI) is a common complication after cardiac surgery and is associated with increased mortality. Amino acids may improve renal perfusion, but their effect in patients undergoing aortic surgery remains unclear. We used the Aortic Surgery Database of the Shanghai Hospital Development Center to emulate a target trial. Patients were classified to one of two exposure strategies: receiving a daily amino acid dose of > 21 g during the first 2 postoperative days, or not receiving amino acid therapy above this threshold. Overlap weighting was used to balance covariates and emulate randomized assignment. The primary outcome was the incidence of AKI. Secondary outcomes included AKI stage, renal replacement therapy, hospital stay, in-hospital mortality, and 30-day mortality. Overall, 1,816 patients were included in the study. The incidence of AKI and 30-day mortality was 37.8% (n = 686) and 1.6% (n = 29), respectively. No significant association was observed between low-dose postoperative amino acid exposure and the incidence of AKI (OR = 0.96, 95% CI: 0.79-1.17, p = 0.70) or 30-day mortality (OR = 1.54, 95% CI: 0.68-3.50, p = 0.30). In subgroup analysis, amino acid exposure was associated with a lower risk of AKI in patients aged ≥ 65 years (OR = 0.71, 95% CI: 0.53-0.95, p = 0.02). The subgroup finding in older patients should be considered exploratory and requires confirmation in future studies.