Predictive Model Development for Major Limb Amputation Risk in Diabetic Foot Ulcers

Overview

This study developed a clinical risk prediction model to objectively estimate the risk of major limb amputation in patients with diabetic foot ulcers (DFU). Using retrospective inpatient data and 22 candidate predictive variables, the model aims to identify high-risk patients to guide clinical decision-making and improve outcomes.

Background

Diabetic foot ulcer (DFU) is a serious complication of diabetes mellitus, often leading to non-traumatic lower extremity amputation (LEA). DFU accounts for approximately 85% of LEAs worldwide, with amputation rates varying by region. Major amputations significantly reduce quality of life and increase mortality, highlighting the need for early risk identification and intervention. Currently, no objective clinical tool exists to predict major amputation risk in DFU patients, underscoring the importance of developing a validated predictive model.

Data Highlights

The study included inpatient data from February 2014 to July 2020, identifying DFU patients via ICD-10 code E14.500×050. Inclusion criteria ensured complete clinical and laboratory data within 3 days of admission and follow-up for major amputation within 1 month. A nested case-control design matched major amputation cases to controls at a 1:4 ratio by sex and age ±5 years. Twenty-two candidate predictive variables were selected based on literature and expert opinion. Major amputation was defined as amputation above the ankle joint.

Key Findings

• DFU is the leading cause of non-traumatic lower extremity amputation, accounting for 85% of such cases globally.
• Major amputation refers to limb loss above the ankle and is associated with higher injury scores and worse quality of life compared to minor amputation.
• The study identified 22 candidate variables, including demographic, laboratory, imaging, and comorbidities, to predict major amputation risk.
• A nested case-control design matched patients undergoing major amputation within 1 month to controls, ensuring robust comparison.
• Severe ischemia (ABI < 0.4), history of amputation, multidrug-resistant infections, coronary and peripheral arterial disease, and chronic renal insufficiency were defined as important clinical factors.

Clinical Implications

The predictive model provides clinicians with an objective tool to assess major amputation risk in DFU patients early during hospitalization. Identifying high-risk individuals allows for targeted interventions to potentially reduce amputation rates and improve patient outcomes. This model supports informed clinical decision-making and patient communication regarding limb salvage versus amputation.

Conclusion

This study successfully developed a clinical risk prediction model for major limb amputation in DFU patients, filling a critical gap in objective risk assessment. Implementation of this tool may enhance early identification of high-risk patients and guide optimal management strategies.

References

1. Global and regional diabetic foot ulcer amputation statistics
2. Chinese and African DFU amputation rates
3. Mortality rates post-amputation in diabetic patients
4. Clinical definitions and diagnostic criteria for DFU complications