Surgical site infections (SSIs) are both common and morbid. SSIs are now the most common and costly of all hospital acquired infections (HAIs), accounting for 20% of all HAIs. SSIs are associated with increased length of stay (LOS) and a 2-11 fold increase in the risk of mortality. Though most patients recover from an SSI without long-term adverse sequelae, 77% of mortalities in patients with a SSI can be attributed to the infection itself.
The incidence of SSI is 2-5% in patients undergoing inpatient surgery. Estimated annual incidence varies widely, ranging from 160,000-300,000 in the United States. These estimates are likely understated given the surveillance challenges following discharge.
The financial burden of SSI is considerable, ranking as the most costly of the HAIs. The annual cost of SSI in the United States is estimated at $3.5-10 billion. Increased costs from SSIs are driven by increased LOS, emergency department visits, and readmissions. On average, SSI extends hospital length of stay by 9.7 days, and increases the cost of hospitalization by over $20,000 per admission. Over 90,000 readmissions annually are attributed to SSI, costing an additional $700 million per year. Because up to 60% of SSIs were estimated to be preventable with the use of evidence-based measures, SSI has become a pay-for-performance metric and a target of quality improvement efforts.
The most widely used definition of SSI has been provided by the Centers for Disease Control and Prevention (CDC). This definition is used for research, quality improvement, public reporting, and pay-for-performance comparisons. According to this definition, SSIs are classified by depth and tissue spaces involved. A superficial incisional SSI involves only the skin or subcutaneous tissue, a deep incisional SSI involves the fascia and/or muscular layers, and an organ space SSI involves any part of the body opened or manipulated during a procedure excluding the previously mentioned layers.
Numerous risk factors have been identified for the development of an SSI following surgery. These risk factors can be broadly separated into intrinsic (patient) factors that are modifiable or non-modifiable, as well as extrinsic (procedure, facility, preoperative, and operative) factors. Potentially modifiable patient risk factors include glycemic control/diabetic status, dyspnea, alcohol and smoking status, preoperative albumin < 3.5 mg/dL, total bilirubin > 1.0 mg/dL, obesity, and immunosuppression. Non-modifiable patient factors include increasing age, recent radiotherapy, and history of skin or soft tissue infection (SSTI). Procedure-related factors include emergency and more complex surgery and wound classification. Facility risk factors include inadequate ventilation, increased operating room (OR) traffic, and appropriate sterilization of equipment. Preoperative risk factors include presence of a pre-existing infection, inadequate skin preparation, hair removal, and antibiotic choice/administration/duration. Intraoperative risk factors include duration of surgery, blood transfusion, maintenance of asepsis, poor quality surgical hand scrubbing and gloving, hypothermia, and poor glycemic control.
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