Acute kidney injury (AKI) is a common complication during the early postoperative period after noncardiac surgery. Patients with AKI are at an increased risk of developing chronic kidney disease, prolonging hospitalization, and experiencing higher rates of morbidity and mortality. Identifying preoperative risk factors for postoperative AKI can significantly contribute to the development of preventive strategies and improved perioperative care in this vulnerable patient population.

The goal of this retrospective study is to investigate the predictive value of preoperative inflammatory status, as measured by complete blood count-derived inflammatory markers, such as the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), derived neutrophil-to-lymphocyte ratio (dNLR), neutrophil-to-lymphocyte*platelet ratio (NLPR), systemic immune-inflammatory index (SII), systemic inflammatory response index (SIRI), and aggregate index of systemic inflammation (AISI), on postoperative AKI in elderly patients undergoing non-cardiac surgery.

Inclusion Criteria:

1. aged ≥ 65 years.
2. general, gynaecological, neurosurgery, orthopaedic, or thoracic surgery.
3. surgery duration lasting longer than one hour.

Exclusion Criteria:

1. patients with an American Society of Anesthesiologists (ASA) physical status V.
2. those with concurrent cardiac, vascular, transplant or urological surgeries.
3. those with end-stage renal disease (i.e. a glomerular filtration rate of 15 mL/min/1.73 m2 or receiving haemodialysis) or a history of kidney transplantation..
4. those did not have sufficient data required for calculation for inflammatory markers or AKI evaluation.

Elderly patients (aged ≥ 65 years) who underwent a non-cardiac surgery at Tongji Hospital between July 2018 and December 2021 were included in our study.