EP623 - Unintentional Preoperative Weight Loss Prior to Elective Colorectal Surgery Increases the Risk of Perioperative Complications: A Retrospective Cohort Study

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Purpose/Background: Preoperative malnutrition is associated with poor perioperative outcomes. Prior to colorectal surgery in particular, preoperative malnutrition predisposes to complications such as surgical site infections, anastomotic leak, and postoperative sepsis. While numerous surrogate markers for preoperative malnutrition have been evaluated, such as hypoalbuminemia and Prognostic Nutritional Index, the impact of unintentional preoperative weight loss in patients who are already underweight or normal weight, has never been evaluated. We designed this population-level, retrospective cohort study to evaluate the impact of unintentional preoperative weight loss on short-term postoperative outcomes following elective colorectal surgery.

Methods/Interventions: Adult patients undergoing elective colectomy and/or proctectomy for colorectal cancer, diverticular disease, and/or inflammatory bowel disease (IBD) between 2016 and 2022 were identified in the American College of Surgeons (ACS) National Quality Improvement Program (NSQIP) database utilizing Current Procedure Terminology (CPT) codes and International Classification of Diseases, Tenth Revision (ICD-10) codes. Patients were included if their body mass indices (BMI) were less than 25 kg/m2. The exposure of interest was 10% weight loss in the six months preceding the date of surgery. The primary outcome was 30-day major postoperative morbidity. The secondary outcomes included 30-day postoperative mortality, postoperative septic complications, 30-day readmission, and postoperative length of stay (LOS). Multivariable regression models were fit for each outcome.

Results/Outcomes: Overall, 51,345 patients were included. There were 4,150 patients that experienced 10% weight loss in the six months and 47,195 that did not. The most common disease processes were colorectal cancer (n=35,049, 68.3%), followed by IBD (n=11,192, 21.8%) and diverticular disease (n=5,104, 9.9%). The majority of patients underwent colectomy with primary anastomosis (n=36,536, 71.2%) and 15.3% (n=7,868) underwent proctectomy. Preoperative weight loss was associated with 15.6% increased odds of experiencing 30-day major postoperative morbidity (95% confidence interval (CI) 1.05-1.28). Preoperative weight loss was also associated with 42.4% increased odds of postoperative septic complications (95%CI 1.20-1.68), 53.5% increased odds of 30-day postoperative mortality (95%CI 1.18-2.00), and 18.8% increased odds of readmission to hospital within 30-days of the index operation (95%CI 1.07-1.32). Postoperative LOS was 0.50 days longer for patients experiencing preoperative weight loss (95%CI 0.37-0.64).

Conclusion/Discussion: Unintentional preoperative weight loss in patients who are underweight or normal weight, according to BMI, prior to elective colorectal surgery is associated with increased odds of postoperative morbidity. These patients are also at risk of having longer postoperative LOS. Preoperative optimization by way of nutritional supplementation and exercise programs are important considerations for underweight and normal weight patients at risk of preoperative weight loss prior to elective colorectal surgery and should be explored through further large prospective trials.