Predictors and costs of surgical site infections in patients with endometrial cancer

Highlights

• MIS approaches decrease the risk of superficial incisional SSI following EC staging.

• Hyperglycemia and smoking are modifiable risk factors that increase organ/space SSI.

• The 30-day costs of SSI are substantial and vary according to SSI type.

Abstract

Objective

Technological advances in surgical management of endometrial cancer (EC) may allow for novel risk modification in surgical site infection (SSI).

Methods

Perioperative variables were abstracted from EC cases surgically staged between January 1, 1999, and December 31, 2008. Primary outcome was SSI, as defined by American College of Surgeons National Surgical Quality Improvement Program. Counseling and global models were built to assess perioperative predictors of superficial incisional SSI and organ/space SSI. Thirty-day cost of SSI was calculated.

Results

Among 1369 EC patients, 136 (9.9%) had SSI. In the counseling model, significant predictors of superficial incisional SSI were obesity, American Society of Anesthesiologists (ASA) score > 2, preoperative anemia (hematocrit < 36%), and laparotomy. In the global model, significant predictors of superficial incisional SSI were obesity, ASA score > 2, smoking, laparotomy, and intraoperative transfusion. Counseling model predictors of organ/space SSI were older age, smoking, preoperative glucose > 110 mg/dL, and prior methicillin-resistant Staphylococcus aureus (MRSA) infection. Global predictors of organ/space SSI were older age, smoking, vascular disease, prior MRSA infection, greater estimated blood loss, and lymphadenectomy or bowel resection. SSI resulted in a $5447 median increase in 30-day cost.

Conclusions

Our findings are useful to individualize preoperative risk counseling. Hyperglycemia and smoking are modifiable, and minimally invasive surgical approaches should be the preferred surgical route because they decrease SSI events. Judicious use of lymphadenectomy may decrease SSI. Thirty-day postoperative costs are considerably increased when SSI occurs.

Introduction

Standard therapy for endometrial cancer (EC) begins with surgery which is essential for treatment, staging, prognostication, and determination of adjuvant treatments [1], [2], [3]. Surgical intervention carries with it inherent risks, including surgical site infection (SSI). The American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) was developed to harness risk-adjusted perioperative data directly from patient medical charts to determine postoperative complications that are preventable with the goal of improving the quality of surgical care. NSQIP has defined 3 categories of SSI: superficial incisional, deep incisional, and organ/space [4], [5], [6], [7], [8] (Box 1). SSI is a major contributor to postoperative morbidity and death [9], [10], [11]. In fact, more than one-third of postoperative deaths are related, in part, to SSIs [9] and SSIs increase the cost of care. Among colorectal patients, SSI increases the cost of care more than $6000 per patient [12].

Minimally invasive approaches to abdominal and pelvic cancers have emerged and evolved over the past several decades. Laparoscopic colorectal, gastric, prostate, and hepatobiliary surgery have been shown to have lower rates of SSI and other postoperative complications, as well as shorter hospital stays, than open surgery [8], [10], [13], [14], [15]. Among women undergoing hysterectomy for benign indications, minimally invasive approaches decrease the risk of procedure-related complications without increasing the cost of care [16], [17]. Laparoscopic staging for EC results in similar intraoperative complication rates and lower rates of overall postoperative complications compared to open staging [18], [19], [20]. Length of hospital stay is substantially shorter with laparoscopic staging; the ability to identify metastatic disease appears similar with laparoscopy [11], [21], and quality of life is improved among women who undergo minimally invasive EC staging [19], [21]. In addition, laparoscopic staging does not appear to adversely affect survival [22].

Our primary objective was to determine perioperative variables associated with the risk of SSI in EC patients, to identify modifiable variables. A counseling model (preoperative variables only) and a global model (preoperative, intraoperative, and postoperative variables) for SSI development were constructed. We also determined the additional 30-day cost to the surgical episode of EC care associated with any SSI and each subtype of SSI that our patients had. Identification of fixed and modifiable variables in the surgical process of care is essential for preoperative patient counseling, risk management, development of preventive strategies, and risk-adjusted reimbursement.