Two-Year Retrospective service evaluation of nutritional outcomes after laparoscopic sleeve gastrectomy utilising 34 French and 60 French sized bougies

Background: Bariatric surgery remains the most effective, long-term treatment for obesity [1], with laparoscopic sleeve gastrectomy (LSG) accounting for 60% of bariatric procedures performed worldwide [2]. Surgical techniques for LSG have been standardised, however, the size of bougie used to model the pouch has not [3]. Due to lack of evidence and guidance, in practice the size of bougie used varies, and further research is required to determine the most effective treatment.
Aim: To compare the weight loss outcomes, and incidence of nutritional deficiency following LSG when using 34Fr and 60Fr bougie at two-year post-operative.
Design: This service evaluation was quantitative secondary data analysis. The study design was a retrospective cohort study.
Methods: A data collection tool was used to extract data from records of patients who underwent a LSG between the years 2016 and 2018. As standard practice in the service, one surgeon uses a 60Fr bougie whilst two use a 34Fr bougie. Patients were assigned groups accordingly, and outcomes of weight, and nutritional deficiencies were recorded at baseline and two years post operatively.
Results: 83 patients underwent a LSG at a specialist centre between 2016 and 2018, all these patients met the inclusion criteria for the service evaluation. Of these, 46 patients had LSG with 34Fr bougie, while 37 patients had LSG with 60Fr bougie. Both groups were similar in terms of age and baseline weight, however, baseline BMI was significantly higher in the 60Fr group. Percentage weight loss at two years post operatively was statistically significantly higher in the 60Fr bougie group, than in the 34Fr bougie group (21.5% (SD= 9.1) vs 14.04% (SD= 12.3), p=0.015 for 60Fr group and 34Fr group respectively). Hedges G was used to determine the effect size, g=-0.64 which indicates a medium effect size. There was little difference in incidence of most nutritional deficiencies. However, patients were significantly more likely to become deficient in vitamin D following LSG with 60Fr bougie, than a LSG with a 34Fr bougie, X2 (1, n=35)=4.88, p=0.041.
Conclusions: This service evaluation found LSG with 60Fr bougie to be more effective for weight loss compared with a 34Fr bougie, however, these patients were also at higher risk of vitamin D deficiency. Further research with a randomised control trial design would address the limitations identified in the current evaluation and is required to fully answer the research question.