A SIMPLE Performance Assessment of Bariatric Procedures and Post-operative Weight Regain

When assessing and reporting the performance of bariatric procedures, longitudinal total weight loss % (TWL%) is the preferred method of choice. This averages out significant individual weight regains. Due to no assessment of individual weight trajectories, numerous patients with weight recidivism are missed in the overall assessment of the applied procedures.

The SIMPLE acronym (Survival analysis of Interpolated weight trajectories in a Markov chain, assessing Predictors, Longitudinal TWL% and individual procedure success and relapse Events) provides a framework to assess the performance of bariatric procedures in everyday practice, identifying a procedures' overall performance both in terms of longitudinal total weight loss % and individual events of weight regain. The SIMPLE approach is demonstrated on a cohort of 907 bariatric patients collected over 7 years. Six hundred eighteen patients received a primary RYGB, 81 a primary SG, while 208 were conversions to either a RYGB (n = 198) or SG (n = 10). Successful surgery was defined as 20% TWL; a weight regain as a 15% increase from the lowest individually attained weight post-surgery.

The longitudinal TWL% performance at 5 years was 34.5%, 21.3%, and 22.9% for the primary RYGB, primary sleeve gastrectomy, and conversion operation, respectively. However, nearly 20% of the conversion operations never reached success, while 33.5% registered a relapse event within 5 years.

The combined approach of the SIMPLE assessment clearly showed that a non-trivial amount of individuals did not achieve success or regained significant weight after surgery. This indicates that a combined approach to reporting bariatric performance is preferred.