eP417 - The Use of Preoperative Enteral Immunonutrition in Patients Undergoing Elective Colorectal Cancer Surgery: A Systematic Review and Meta-Analysis

Purpose/Background: Immunonutrition products, composed of arginine, omega-3 fatty acids, glutamine, and/or nucleotides, are often advertised as being effective preoperative agents for reducing negative clinical outcomes like infection and inflammation associated with deficient preoperative nutrition prior to colorectal surgery. While various studies have begun exploring the role of immunonutrition in preoperative care, demonstrating both safety and efficacy, immunonutrition has yet to become the standard of care for patients undergoing elective colorectal cancer surgery. We designed the present systematic review and meta-analysis with the aim of comparing adult patients receiving enteral immunonutrition prior to elective colorectal cancer surgery to those receiving conventional preoperative nutrition.Methods/Interventions: This systematic review was completed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The following databases were searched from database inception to March 2023: MEDLINE, Embase, and CENTRAL. Articles were included if they were randomized control trials (RCTs) or cohort studies evaluating adult patients (i.e., over the age of 18) undergoing elective colorectal cancer surgery comparing preoperative enteral immunonutrition to conventional preoperative nutrition protocols. The primary outcomes of interest included surgical site infection (SSI), anastomotic leak, overall postoperative morbidity, 30-day readmission, and postoperative length of stay (LOS). A pairwise meta-analyses using inverse variance random effect was performed. Risk of bias was assessed with Cochrane risk of bias assessment tools. The GRADE approach was conducted to assess quality of evidence.Results/Outcomes: After reviewing 2,508 relevant citations, seven observational studies met inclusion criteria. Overall, 483 patients (mean age: 65.810.2, 42.7% female) received preoperative immunonutrition and 977 patients (mean age: 63.38.4, 51.6% female) received conventional preoperative nutrition. Most operations were performed laparoscopically (97.5%). The most common indication for colorectal surgery was [insert CRC, diverticular disease, whatever was most common] (%). Across five studies, there was a 34% relative risk reduction in the risk of SSI in the immunonutrition group (RR 0.66, 95%CI 0.41-1.05, p=0.08, I2=9%). Across six studies, there was a 43% relative risk reduction in the risk of anastomotic leak in the immunonutrition group (RR 0.57, 95%CI 0.27-1.20, p=0.14, I2=0%). Across five studies, postoperative LOS was 0.42 days shorter in the immunonutrition group (MD 0.42, 95%CI -0.03-0.87, p=0.07, I2=33%). Only two studies reported 30-day readmission (RR 0.82, 95%CI 0.20-3.46, p=0.79, I2=31%) and there were insufficient data across studies to allow for pooling of overall postoperative morbidity. GRADE certainty of evidence was very low for all outcomes.Conclusion/

Discussion: The impact of preoperative enteral immunonutrition prior to colorectal surgery remains unclear. Point estimates derived from the present meta-analyses suggest important benefits; however, the wide corresponding 95% confidence intervals create significant uncertainty. Further study by way of large RCTs is required.