preoperative very low energy diets for obese patients undergoing non-bariatric surgery

Conditions: Obesity; Non-Bariatric Surgery; Preoperative Weight Loss; Preoperative Optimization

Summary: the prepare pilot randomized controlled trial (rct) is a multi-center, parallel, blinded rct that aims to assess the feasibility of a full rct comparing preoperative very low energy diets (vleds) to standard of care prior to elective non-bariatric surgery for obese patients in terms of overall 30-day postoperative morbidity. adult patients with body mass indices (bmis) greater than 30 kg/m2 will be randomized 1:1 to receive 3-weeks of preoperative vled plus preoperative weight loss counselling or preoperative weight loss counselling alone. this trial will enroll patients to assess recruitment, compliance, and follow-up completion to assess the feasibility of a full rct powered to assess for differences in 30-day postoperative between vleds and standard of care arms.

obesity is a worldwide epidemic affecting upwards of 700 million people. the economic burden in the united states and canada are estimated at over $2 trillion and $100 billion united states dollars (usd), respectively, and the resultant healthcare consequences can be devastating for systems and patients alike. obesity is a systemic disease with devastating consequences for patients undergoing any form of operative intervention. obese patients presenting in need of medical and surgical intervention are at 2-to-6 fold higher risk of prolonged hospitalization, infectious morbidity, venous thromboembolism, and more. to pre-emptively mitigate some of these concerns, prescribed preoperative weight loss via vleds has become a standard of care for obese patients undergoing bariatric surgery (i.e., weight loss surgery). while vleds have become a standard in obese patients undergoing bariatric surgery, largely due to the significant reduction of peri-organ fat for better visualization, their application to obese patients undergoing other types of surgery remains limited. a previous systematic review and meta-analysis that identified 13 studies evaluating the use of preoperative vleds in obese patients undergoing orthopaedic, vascular, colorectal, upper gastrointestinal, gynecological, and a variety of general surgery procedures for benign disease (e.g., cholecystectomy, abdominal wall hernia). while data were heterogenous, preoperative vleds reliably resulted in significant weight loss (3.2-19.2kg) with high rates of compliance to the protocols (94-100%). adverse event rates were low (\ 30kg/m2) receiving vleds versus control prior to elective non-bariatric surgery in terms of perioperative outcomes.

Eligibility criteria:
inclusion criteria: * older than 18 years of age * bmi of greater than 30 kg/m2 * undergoing major elective non-bariatric surgery. major surgery is defined as any operation performed under general anesthesia requiring a skin incision extending beyond the subcutaneous tissue. exclusion criteria: * undergoing bariatric surgery * undergoing neurologic surgery * undergoing urgent or emergent surgery * recently diagnosed myocardial infarction or unstable angina (i.e., within past six months) * diagnosed moderate-to-severe renal dysfunction (i.e., egfr less than 30ml/min/1.73m2) * diagnosed severe liver dysfunction (i.e., cirrhosis, portal hypertension, hepatic encephalopathy, hepatorenal syndrome) * recently diagnosed alcohol or drug use disorders (i.e., excessive use of substance within past six months) * experienced a recent episode of gout (i.e., within past six months) * medical history of porphyria; (10) known allergy to any optifast ingredient * enrolled in other prospective studies with similar interventions and/or outcomes. co-enrollment may be deemed appropriate if the steering committees of the respective trials review the details of participation. * pregnant or breastfeeding women * patients unable to provide informed consent.