Incidence and Predictors of Surgical Site Infection Complications in Diabetic Patients Undergoing Lower Limb Amputation.

Background: Surgical site infections (SSIs) following lower extremity amputations (LEAs) are a major cause of patient morbidity and mortality. The objectives of this study are to investigate the annual incidence of SSI and risk factors associated with SSI after LEA in diabetic patients.

Methods: LEAs performed on diabetic patients between 2005 and 2017 were retrospectively analyzed from the American College of Surgeons National Surgical Quality Improvement Program database. Incidence rates were calculated and analyzed for temporal change. Multivariable logistic regression was conducted to identify the independent predictors of SSIs in LEA.

Results: In 21,449 diabetic patients, the incidence of SSIs was 6.8% after LEA, with an overall decreasing annual trend (P = 0.013). Amputation location (below-knee in reference to above-knee) [OR (95% CI): 1.35 (1.20 - 1.53), P <0.001], smoking [OR (95% CI): 1.25 (1.11 - 1.41), P <0.001)], female sex [OR (95% CI): 1.16 (1.03 - 1.30)], preoperative sepsis [OR (95% CI): 1.24 (1.10 - 1.40), P <0.001], P = 0.013], emergency status [OR (95% CI): 1.38 (1.17 - 1.63), P <0.001], and obesity [OR (95% CI): 1.59 (1.12 - 2.27), P = 0.009] emerged as independent predictors of SSIs, while moderate/severe anemia emerged as a risk-adjusted protective factor [OR (95% CI): 0.75 (0.62 - 0.91), P = 0.003]. Sensitivity analysis found that moderate/severe anemia, not body mass index (BMI) class, remained a significant risk factor in the development of SSIs in below-the-knee amputations; in contrast, higher BMI, not preoperative hematocrit, was significantly associated with an increased risk for SSI in above-the-knee amputations.

Conclusions: The incidence of SSIs after LEA in diabetic patients is decreasing. Overall, below-knee amputation, smoking, emergency status, and preoperative sepsis appeared to be associated with SSIs. Obesity increased SSIs in above-the-knee amputations, while moderate/severe preoperative anemia appears to protect against below-the-knee SSIs. Surgeons should take predictors of SSI into consideration while optimizing care for their patients, and future studies should investigate the role of preoperative hematocrit correction and how it may influence outcomes positively or negatively.