Dexmedetomidine reduces acute kidney injury in high-risk but not low-risk patients after non-cardiac surgery: secondary analysis of a randomized controlled trial

PURPOSE: Acute kidney injury (AKI) is a significant postoperative complication associated with poor long-term outcomes. Dexmedetomidine, a selective α₂-adrenergic agonist with anti-inflammatory properties, may protect the kidney during non-cardiac surgery. This study examined whether intraoperative dexmedetomidine reduces AKI in both high-risk and low-risk patients. METHODS: This was a secondary analysis of a randomized double-blind placebo-controlled trial. Patients aged ≥ 60 years scheduled for elective non-cardiac surgery expected to last ≥ 2 h under general anesthesia were enrolled and classified as low-risk or high-risk using the General Surgery Acute Kidney Injury Risk Index. Participants were randomly allocated to receive intraoperative dexmedetomidine (loading dose 0.6 μg/kg over 10 min before induction, followed by 0.5 μg/kg/h until 1 h before surgery end) or normal saline. The primary endpoint was AKI incidence within 7 postoperative days. RESULTS: Among high-risk patients, AKI occurred in 12.6% (13/103) of the dexmedetomidine group versus 23.4% (25/107) of controls (RR 0.54, 95% CI 0.29 to 1.00, P = 0.043); after multivariable adjustment, dexmedetomidine remained independently associated with lower AKI risk (OR 0.44, 95% CI 0.20 to 0.98, P = 0.045). In contrast, low-risk patients showed no significant difference with or without dexmedetomidine (7.9% vs 9.6%; RR 0.82, 95% CI 0.44 to 1.55, P = 0.543; adjusted OR 0.65, 95% CI 0.30 to 1.38, P = 0.260). Urological surgery was an independent predictor of AKI across the entire cohort. CONCLUSION: Intraoperative dexmedetomidine was associated with lower risk of AKI in high-risk but not in low-risk patients undergoing non-cardiac surgery.