Perioperative Risk Factors and Development of a Clinical Risk Score for Postoperative Acute Kidney Injury in Patients Undergoing Lower Limb Amputation for Vascular Disease

IntroductionPerioperative acute kidney injury (AKI) is a recognised complication of vascular surgery and is associated with adverse short-and long-term outcomes.Various perioperative factors, including pre-existing comorbidities, baseline kidney function, intraoperative haemodynamic changes, vasopressor use, and nephrotoxic medications, may contribute to the development of postoperative AKI.However, data addressing AKI specifically in patients undergoing lower limb amputation remain limited.This study aimed to evaluate perioperative risk factors and develop a risk scoring model to predict postoperative AKI in this population. MethodsData from 101 patients were collected using HIVE (Epic Systems Corporation, Verona, Wisconsin, USA), a trust-wide electronic patient record (EPR) system used in Manchester Royal Infirmary, Manchester NHS Foundation Trust.Data were extracted across two phases, preoperative and intraoperative.Data were then imported onto Statistical Package for the Social Sciences (SPSS; IBM Corp., Armonk, New York, USA) software for further analysis.Following this, relevant variables were used to develop a risk prediction model and identify risk factors. ResultsPostoperative AKI was observed in 12.8% of the patients (n=13).The development of postoperative AKI with statistical significance was observed in patients with higher baseline serum creatinine level, low estimated glomerular filtration rate (eGFR) as well as patients with comorbidities like heart failure and chronic kidney disease (CKD).Based on the identified risk factors, points were assigned proportional to their odds ratio and a simplified risk calculation model was developed that stratify patient into low, medium or high risk. DiscussionThis simplified risk scoring model allows for rapid classification of patients into low-, medium-or high-risk categories.Notably, risk increases substantially across categories, reinforcing the model's clinical utility: 5.88% in low-, 38.46% in medium-, and 100% in high-risk patients.This contrast underscores the significant role that risk stratification plays in clinical decision-making.Having a risk score could be invaluable in guiding early interventions prior to surgery, potentially reducing postoperative AKI risk.One limitation of the model is the potential impact of loss of muscle mass following amputation, which may affect the accuracy of postoperative serum creatinine measurements, impacting the assessment of kidney function.