The goal of this retrospective observational study is to learn about the intervenable risk factors of postoperative acute kidney injury (AKI) and in-hospital mortality among adult patients undergoing major surgery. The main questions it aims to answer are:

1. Does preoperative usage of potential nephrotoxic medications (eg., proton pump inhibitor, non-steroidal anti-inflammatory drugs) increase the risk of postoperative AKI and in-hospital mortality?
2. Does preoperative status (eg., malnutrition, hypoalbuminemia, hypomagnesemia) increase the risk of postoperative AKI and in-hospital mortality?
3. Are there intervenable risk factors of postoperative AKI and in-hospital mortality?
4. Are there special risk factors of postoperative AKI and in-hospital mortality in specific patients (eg. elderly, diabetics)? The study will be conducted in retrospective cohort of patients undergoing major surgery. Participants are followed until discharge.

Acute Kidney Injury (AKI), characterized by a rapid decline of kidney function, is a common but serious postoperative complication in surgical patients, with an incidence ranging from 5.3% to 18.4%. Postoperative AKI is associated with increased mortality, prolonged hospital stays, and higher medical costs. Survivors are also prone to developing chronic kidney disease (CKD) or even end-stage renal disease (ESRD) . Identifying intervenable risk factors of postoperative AKI can help clinicians develop targeted strategies for high-risk patients.

Inclusion Criteria:

• Age≥18 years
• Hospitalized at Peking University First Hospital (PKUFH) between January 1, 2018, and December 31, 2020
• Undergoing major surgery during hospital stay

Exclusion Criteria:

• With fewer than two serum creatinine (SCr) measurements during hospitalization, or lack of postoperative SCr assessment
• With pre-exsiting CKD G5 (including long-term dialysis, prior/current kidney transplantation, or baseline estimated glomerular filtration rate [eGFR]<15mL/min/1.73m^2) at admission
• Undergoing radical or partial nephrectomy during current hospitalization
• Developing AKI prior to surgery or within 24 hours after admission (with admission diagnosis of AKI or meeting AKI criteria within 24 hours)
• With hospital stay < 24 hours

Consecutive hospitalized adult patients (≥18 years) undergoing major surgery at Peking University First Hospital (PKUFH) between January 1, 2018, and December 31, 2020.

The datasets are not publicly available as they are protected by Peking University First Hospital. Access requests should be directed to the principal investigator.