Deep Venous Thrombosis and Pulmonary Embolism after Lower Extremity Amputation in Patients with Diabetes

This study aims to identify risk factors for deep venous thrombosis (DVT) and pulmonary embolism (PE) in patients with diabetes mellitus (DM) undergoing a lower extremity amputation (LEA). A retrospective analysis of 36,445 LEA cases from the American College of Surgeons-National Surgical Quality Improvement Program (ACSNSQIP) database was performed. 23,380 patients with DM and 13,065 patients without DM were evaluated to determine whether DM is correlated with an increased risk of DVT and PE. Specific risk factors for DVT and PE in this population were also evaluated. The incidence of DVT in post-LEA patients with DM was 0.94% compared to 1.36% in patients without DM (p=0.0002). The incidence of PE in patients with DM was 0.37% compared to 0.54% in patients without DM (p<0.0001). Although statistically significant, this small increase in DVT/PE risk appears to be driven by a higher proportion of "completely dependent" patients without DM (p<0.0001). Patients with "completely dependent" pre-op functional status were 2.59 times more likely to develop a DVT (95% CI: 1.81-3.70) and 3.36 times more likely to experience a PE (95% CI: 1.97-5.72), while "independent" patients were significantly less likely to experience either complication. Level of amputation (LOA) was also associated with an increased risk of DVT and PE. Patients who underwent a below knee amputation (BKA) were 2.12 times more likely to experience a DVT/PE (95% CI: 1.40-3.12) and patients with an above knee amputation (AKA) were 1.82 times more likely to experience a DVT/PE (95% CI: 1.40-3.21). Patients who underwent a transmetatarsal amputation (TMA) were significantly less likely to experience either complication. Other statistically significant risk factors identified in this study include prior myocardial infarction, ASA classification of III-V, and female sex. Patients with a history of dialysis within 2 weeks of surgery had an increased risk of DVT (OR: 1.52, 95% CI: 1.15-2.02); however, no increased risk of DVT/PE in patients with Chronic Kidney Disease (CKD) stage III-V was found (OR: 1.19, 95% CI: 0.97, 1.45). Although DM is not associated with increased risk of DVT/PE, LOA is a significant predictor of DVT/PE risk. Diabetics with peripheral neuropathy may delay seeking treatment due to lack of pain, potentially resulting in higher LOA. Physicians should emphasize rapid evaluation and management of pressure sores to minimize LOA. Prophylactic antithrombotic protocols should also be considered for patients undergoing a high level amputation and for patients with comorbid risk factors such as cardiovascular disease or dependent functional status.