Review Question - QID 219593

The risk factors associated with the increased risk of surgical site infection after spinal surgery include prolonged operative time greater than 3 hours, diabetes, posterior approach, and elevated body mass index greater than 35.

Surgical site infections are the most common complication after spinal surgery. Surgical site infections are classified as superficial or deep and depend on whether the fascial layer is violated. Additionally, the infection is defined as acute if occurring within three weeks of the surgery, and chronic if longer than 3 weeks from surgery. The incidence of surgical site infection is reported as high as 18%. Risk factors for surgical site infection include active smoker, increased subcutaneous fat thickness, preoperative albumin <20mg/dl, diabetes and hgba1c >7.5%, age >70 years, prolonged operative time greater than 3 hours, posterior approach, and elevated BMI >35.

Yao et al. Performed a meta-analysis of more than 94 studies evaluating the risk factors of surgical site infection in adult spine surgery. They found BMI >35, diabetes, multiple medical comorbidities, current smoker, malnutrition, preoperative radiation, intraoperative transfusion, and combined anterior/posterior approach were associated with increased risk for surgical site infection. Therefore, they concluded that there are numerous risk factors contributing to the risk of surgical site infection, both modifiable and non-modifiable, and should be optimized prior to surgery.

Fei et al. performed a review of twelve studies that investigated risk factors for superficial surgical site infection following spinal surgery that included 13,476 patients. Their review found that the most important predictors of surgical site infection were diabetes, prolonged operative time >3 hours, BMI >35, posterior approach, and surgery on more than 7 intervertebral levels. Their conclusion was similar to the findings of Yao et al. demonstrating both modifiable and non-modifiable risk factors prior to surgery.

Xiong et al. Reviewed 668 patients undergoing primary posterior cervical instrumented spinal surgery with 212 patients (31.7%) screened for MRSA preoperatively, of which 6 (2.8%) were colonized for MRSA. They had twelve patients (1.8%) who ultimately required irrigation and debridement but found that preoperative MRSA testing was not associated with postoperative irrigation and debridement risk. Therefore, they concluded that there was no association between preoperative nasal MRSA screening and surgical site infections in patients undergoing primary cervical instrumentation.

Incorrect Answers:
Answer 1: Patients over the age of 70 years old are at increased risk of surgical site infections.

Answer 2: Prolonged operative times longer than 3 hours are associated with a significantly increased risk of surgical site infections following posterior lumbar fusion surgery.

Answer 4: The patient’s BMI is elevated at 29.9, but categorized as overweight and not obese. The risk of surgical site infection is significantly increased in obese patients with a BMI >30.

Answer 5: While active smoking is a significant risk factor for surgical site infection, the patient is a former smoker and this does not increase their risk of a surgical site infection.