Effects of lifestyle and educational bridging programs before bariatric surgery on postoperative weight loss-a systematic review and meta-analysis

Objective: To fulfill the requirements for bariatric surgery, patients often need to participate in mandatory pre-operative lifestyle interventions (PLI). Currently, the efficacy of multi-month PLI-programs on body mass index (BMI) reduction from the start of the program (T0) through the immediate pre-operative time point (T1) to one-year post-surgery (T2), and how the amount of pre-operative BMI reduction affects post-operative outcome (T1 to T2) is unclear. The aim of this meta-analysis was to analyze the effects of PLI on body mass index (BMI) one-year post-surgery. Method: A systematic literature search was conducted according to PRISMA criteria. Randomized controlled trials that implemented PLI lasting 1-8 months before bariatric surgery were included. The BMI of the intervention group was compared with a control group before participation in the PLI (T0), after completion of the program before surgery (T1) and one-year post-surgery (T2). Finally, the impact of successful BMI reduction at T1 on BMI at T2 was analyzed. Results: N=345 patients derived from 4 studies undergoing PLI reduced their BMI at T1 by 1.5 units compared to the control group (95% CI: -2.73, -0.28). One-year post-surgery, both groups had lost comparable BMI points. The influence of reduced BMI at T1 on weight status at T2 is unclear due to the lack of available studies. Other endpoints and subgroup analyses were rarely examined. Conclusions: PLI reduce BMI before bariatric surgery more effectively than usual care. These differences are not detectable one-year post-surgery. Although a short-term energy reduction period before surgery is clearly important to minimize surgery risks, it is currently unclear whether, and if so under what circumstances, participation in a PLI is beneficial.