Redefining Risk Assessment for Upper Extremity Amputation in Male Diabetic Patients: A National Analysis of Outcomes Using ACS-NSQIP Data (2015–2021)

Introduction: Upper extremity amputation in diabetic male patients presents a high-risk surgical scenario with substantial morbidity. Traditional risk models often fail to capture the multifactorial complexity of this population. This study aimed to validate the Combined ASA–RAI–Preoperative Acute Severe Condition (CARP) score as a composite frailty index to improve risk stratification. Methods: A retrospective cohort study was performed using the ACS-NSQIP database (2015–2021). Adult male diabetic patients undergoing upper extremity amputation were identified using CPT codes. Patients with cancer, infection, emergency surgery, age ≥90, or missing data were excluded. Frailty indices including RAI, ASA, PACS, GNRI, and mFI-5 were analyzed. Multivariable logistic regression and AUROC analysis were used to evaluate predictive performance. Results: Among 829 patients, PACS and GNRI were the strongest individual predictors of adverse outcomes. The CARP score outperformed all individual indices across major complications (AUROC 0.748), mortality (2.17%), non-home discharge (11.1%), and extended length of stay (23.2%). Bootstrap validation confirmed minimal optimism bias. Conclusion: The CARP score offers superior predictive accuracy for adverse postoperative outcomes in diabetic male patients undergoing upper extremity amputation and should be considered for clinical implementation.