The primary objectives of study is to compare the difference in the incidence of postoperative AKI between frail and non-frail patients. The secondary objectives of study was to compare the differences in intraoperative blood pressure fluctuations, the incidence and duration of intraoperative hypotension, postoperative extubation time, postoperative complications, length of hospital stay and hospitalization expenses between frail and non-frail patients, and use mediating effect analysis to examine the magnitude of the effect of intraoperative blood pressure on postoperative acute kidney injury caused by frailty.

This study is a single-center prospective cohort study. It is expected to include patients who meet the inclusion and exclusion criteria from July 2025 to February 2026. The demographic characteristics, laboratory indicators, preoperative comorbidities of the patients will be recorded and frailty assessment will be conducted within one week before the operation. The patients were divided into the frail group and the non-frail group. Record the surgery-related information of the patient on the day of the operation. During the operation, vital signs such as the patient's blood pressure and heart rate were routinely detected. The anesthesiologist adopted an experience-guided anesthesia management approach, and the doctor in charge of anesthesia management was also unaware of the patient's frailty status. Record the indicators such as the dosage of anesthetic drugs during the operation, the duration of surgical anesthesia, the use of vasoactive drugs and the fluid intake and output of the patients. The incidence of AKI, postoperative extubation time, the incidence of in-hospital complications, the length of hospital stay and the hospitalization costs of the patients were recorded after the operation.

Inclusion Criteria:

• 18 years old or above
• Undergo non-cardiac surgery

Exclusion Criteria:

• At least one measurement of serum creatinine (SCr) was not conducted before and after the operation
• End-stage renal disease (ESRD) that has received dialysis within the past year
• Baseline SCr ≥ 4.5 mg/dl (because the clinical criteria for AKI based on elevated SCr may not be applicable to these patients)
• Acute kidney injury occurred within 7 days before the operation
• No frailty assessment was conducted
• The surgical procedure is renal surgery
• The operation time is less than 2 hours

Patients who underwent non-cardiac surgery at Zhongda Hospital Southeast University.