Preoperative dietitian-led Very Low Calorie Diet (VLCD) Clinic for adults living with obesity undergoing gynaecology, laparoscopic cholecystectomy and hernia repair procedures: a pilot parallel randomised controlled trial.

Obesity can increase the risk of postoperative complications. Despite increased demand for patients living with obesity to lose weight prior to common surgical procedures, the impact of intentional weight loss on surgical outcomes is largely unknown. We aimed to conduct a pilot study to assess the feasibility of a full-scale randomised controlled trial (RCT) to examine the effect of preoperative dietitian-led Very Low Calorie Diet (VLCD) Clinic on surgical outcomes in gynaecology and general surgeries. Between August 2021 and January 2023, a convenience sample of adults living with obesity (BMI ≥ 30 kg/m2) awaiting gynaecology, laparoscopic cholecystectomy and ventral hernia repair procedures were randomised to dietitian-led VLCD (800-1000 kcal using meal replacements and allowed foods), or control (no dietary intervention), 2-12 weeks preoperatively. Primary outcome was feasibility (recruitment, adherence, safety, attendance, acceptability and quality of life (QoL)). Secondary outcomes were anthropometry and 30-d postoperative outcomes. Outcomes were analysed as intention-to-treat. Fifty-one participants were recruited (n 23 VLCD, n 28 control), mean 48 (sd 13) years, 86 % female, and mean BMI 35·8 (sd 4·6) kg/m2. Recruitment was disrupted by COVID-19, but other thresholds for feasibility were met for VLCD group: high adherence without unfavourable body composition change, high acceptability, improved pre/post QoL (22·1 ± 15 points, < 0·001), with greater reductions in weight (-5·5 kg VLCD v. -0·9 kg control, P < 0·05) waist circumference (-6·6 cm VLCD v. +0·6 control, P < 0·05) and fewer 30-d complications (n 4/21) than controls (n 8/22) (P > 0·05). The RCT study design was deemed feasible in a public hospital setting. The dietitian-led VLCD resulted in significant weight loss and waist circumference reduction compared with a control group, without unfavourable body composition change and improved QoL.

Impact of a dietitian-led very low calorie diet clinic on perioperative risk for patients with obesity awaiting elective, non-bariatric surgery: A retrospective cohort study.

BACKGROUND: Despite a lack of evidence that intentional weight loss reduces the risk of postoperative complications, adults with obesity are commonly asked to lose weight before elective surgery. We hypothesized that patients undertaking dietitian-led preoperative, very low calorie diet treatment could reduce perioperative surgery risks, as per validated risk scoring systems. The purpose of this study was to measure the impact of a dietitian-led preoperative very low calorie diet clinic on the American Society of Anesthesiologists physical status scores and National Surgical Quality Improvement Program Surgical Risk Calculator scores for patients with obesity awaiting non-bariatric elective surgery. METHODS: This retrospective cohort study included patients referred to the preoperative dietitian-led very low calorie diet clinic before elective surgical procedures over a 2-year-9-month period. The dietitian prescribed individualized, very low calorie diet-based treatment. Primary outcomes were changes in the American Society of Anesthesiologists and Surgical Risk Calculator scores from pretreatment until surgery. RESULTS: A total of 141 eligible participants (48 ± 13.4 years, 76% women, body mass index 41.7 ± 6.3 kg/m2) demonstrated clinically significant weight loss (mean 7.1 ± 6.1kg, 5.2% body weight, P < .001). Median treatment duration was 13 weeks (interquartile range 6.2-19.2 weeks). Five participants (3.5%) avoided surgery due to weight loss-related improvements in their condition. American Society of Anesthesiologists scores improved for 16% (n = 22/141) of participants. Overall, the median surgical risk calculator estimated risk of 'serious' and 'any' postoperative complication reduced from 4.8% to 3.9% (P < .001) and 6% to 5.1% (P < .001), respectively. Reduction in all Surgical Risk Calculator scores occurred, including surgical site infection, re-admission, and cardiac events (P < .05). CONCLUSION: The dietitian-led preoperative, very low calorie diet clinic improved American Society of Anesthesiologists and Surgical Risk Calculator scores for non-bariatric elective surgery patients with obesity. Randomized controlled trials comparing this approach with a control group are warranted.

Elective Surgery in Adult Patients with Excess Weight: Can Preoperative Dietary Interventions Improve Surgical Outcomes? A Systematic Review.

This systematic review summarises the literature regarding the impact of preoperative dietary interventions on non-bariatric surgery outcomes for patients with excess weight/obesity, a known risk factor for poor surgical outcomes. Four electronic databases were searched for non-bariatric surgery studies that evaluated the surgical outcomes of a preoperative diet that focused on weight/fat loss or improvement of liver steatosis. Meta-analysis was unfeasible due to the extreme heterogeneity of variables. Fourteen studies, including five randomised controlled trials, were selected. Laparoscopic cholecystectomy, hernia repair, and liver resection were most studied. Diet-induced weight loss ranged from 1.4 kg to 25 kg. Preoperative very low calorie diet (≤800 kcal) or low calorie diet (≤900 kcal) for one to three weeks resulted in: reduction in blood loss for two liver resection and one gastrectomy study (-27 to -411 mL, p < 0.05), and for laparoscopic cholecystectomy, reduction of six minutes in operating time (p < 0.05) and reduced difficulty of aspects of procedure (p < 0.05). There was no difference in length of stay (n = 7 studies). Preoperative ≤ 900 kcal diets for one to three weeks could improve surgical outcomes for laparoscopic cholecystectomy, liver resection, and gastrectomy. Multiple randomised controlled trials with common surgical outcomes are required to establish impact on other surgeries.