Introduction
The Department of Surgery at the University of Calgary has a long and proud tradition of research surrounding surgical site infections (SSI). More specifically, former surgeon and Department Chair Dr. Peter Cruse prospectively studied 23,649 surgical wounds following operative intervention. This massive study remains unmatched in size by a single institution publication. Dr. Cruse and Ms. Rosemary Foord demonstrated a decrease in SSI rates with the pre-surgical use of hexachlorophene wash and by not shaving the surgical site1. They observed an increase in SSI rates with advanced age, use of drains, prolonged hospital stay before the operation, and longer operative times. Dr. Cruse is directly responsible for confirming the validity of the wound classification system currently in use throughout the world (clean, clean-contaminated, contaminated, and dirty). We propose to carry on the tradition of this line of investigation, reinforcing Calgary as a world leader in SSI research.
SSI are a frequent and costly source of post-operative morbidity. They are the most common complication following gastrointestinal and biliary tract surgery, occurring in 5-30% of patients. SSI are associated with a two-fold increased risk of in-hospital mortality, a 50% increase in intensive care admission, a 6-day mean increase in hospital stay, and a five-fold increased rate of readmission. SSI also have additional and highly negative consequences in the treatment of oncology patients. More specifically, medical oncologists wait until all operative wounds are entirely healed prior to beginning adjuvant chemotherapy. This delay is both oncologically concerning, as well as psychologically destructive to highly stressed patients with poor associated survivals. Furthermore, with a significant SSI, this delay often leads to a total omission of adjuvant therapies as a whole. The estimated increased cost per SSI ranges from $1,300 to $5,000 in the United States. In Canada, a 1998 study estimated $3,937 per infection, resulting from increased hospital stay, as well as emergency department and clinic visits. The implications of these costs have now become paramount given that both U.S. Medicare and Medicaid currently deny any reimbursement for patients who obtain an SSI while admitted to hospital. In addition, patients who develop SSI experience psychosocial distress, loss of income, and loss of productivity. Prevention of SSI is therefore a vitally important goal in delivering quality care to patients. The SSI rate is 40-50% in patients undergoing pancreatoduodenectomy with intrabiliary stents, the population of interest for this study.
Wound protectors are devices designed to protect the abdominal wound tissue edges from contamination and trauma during laparotomy. A major reason for their conception and use is a theoretical reduction in risk of SSI. Various devices with similar intent have been described since the 1960s, falling into two main design categories: (1) Those with an internal and external ring connected by impervious plastic, and (2) Those with a single, internal ring connected to a drape which extends outward, over the wound edges and onto the abdomen where they are affixed with adhesive or clips.A recent meta-analysis of randomized controlled trials was conducted by a team led by the Principal Investigator to evaluate whether impervious plastic wound protectors reduce the risk of surgical site infection following gastrointestinal and biliary surgery. Six studies representing 1,008 patients were included. Wound protectors were associated with a 45% decrease in SSI (p = 0.04). The Alexis Wound Protector, a ring based model, had evidence of superiority to other products and has been selected for this study based on this finding.
Methods
Recruitment: Contact information for study candidates will be obtained by the project's research fellow from the offices of the participating (4) surgeons. Patients will be contacted prior to their surgery by the research fellow and will be provided information regarding the study. Patients who consent to participate will be randomized.
Randomization process: This study is a simple, two-arm randomized clinical trial (RCT) with block randomization. Allocation will be concealed before the patient enters study. Patients will be randomized by the Research fellow following consent. Allocation will be provided to surgeon in a sealed envelope to be opened immediately before surgery. Patients and the data analyst will be blind to allocation; the surgeons cannot be blinded. Charts will be blinded for data abstraction.
Data collection: Information will be collected by chart review from the operative report and patient records by the research fellow in the Department of Surgery.
Data elements to be collected include:
Date of birth, Sex, American Society of Anesthesiologist (ASA) score, Surgeon, Site (if more than one facility), Fellow/resident/clerk present (y/n), Surgical procedure, Antibiotic prophylaxis received (y/n) and time given, Information about repeat antibiotic prophylaxis (for longer surgeries), Antibiotic type/combination, Type of wound protector and manufacturer, Prep type (ETOH based, chlorhexidine based, iodine based), Hair removal, Medications given, Packing, Drains, Wound classification, Wound closure technique \& dressing type, Length of surgery, Surgical suite infection control factors (e.g. UV, OR ventilation) if these differ, Transfusions,
Patient records:
Current use of corticosteroids/immune suppressant, Preoperative chemotherapy, Smoking history, Co-morbidities (diabetes, hypertension, etc.), Body Mass Index (BMI).
The presence of an SSI will be determined according to guidelines developed by the Centers for Disease Control. More specifically, SSI is defined as being the presence of at least one of the following:
1. Purulent drainage, with or without laboratory conformation, from the superficial incision.
2. Organisms isolated from an aseptically obtained culture of fluid from the superficial incision.
3. At least one of the following signs or symptoms of infection:
pain or tenderness, localized swelling, redness and superficial incision is deliberately opened by surgeon, unless incision is culture-negative.
4. Diagnosis of superficial incisional SSI by the surgeon or attending physician.
Analysis
We will use an intention to treat approach to the analysis to avoid the effects of crossover and dropout. To achieve a power (superiority trial) of 90%, and alpha of 0.05 with a 5% crossover and a 40% expected SSI rate in control versus 10% in wound protector groups, the total sample size is 78 (i.e. 39 in each arm).
Resources
This project will capitalize on an existing research team who can work collaboratively with the Principal Investigator and research assistant to carry out the project effectively and efficiently. The current research team includes a clinical research fellow with experience recruiting research participants from this patient population and a project manager who can assist with ethics applications, manuscript writing and reporting. Additionally, the Principal Investigator will benefit from mentorship by an experienced investigator who can provide guidance not only on methodology, interpretation of data and publication strategies, but also on the day-to-day logistics of running a research project.
