Lack of Standard Definitions of Primary and Secondary (Non)responders After Primary Gastric Bypass and Gastric Sleeve: a Systematic Review.

Lack of standard definitions of primary and secondary (non)responders after RYGB and SG makes it impossible to compare the literature. The aim was to analyze the different definitions used. MEDLINE® was searched for literature published between 01-07-2014 and 01-07-2017 concerning (1) patients who received a primary RYGB or SG and (2) the outcomes of primary and secondary (non)responders. One hundred twelve out of 650 papers were eligible. Forty out of 47 papers described a definition of weight loss success. Sixty-seven out of 112 papers mentioned weight loss failure of which 42 described a definition, in total 23 different definitions. Weight regain was mentioned in 77 papers; only 21 papers provided a definition. The recent literature regarding definitions of these outcomes is highly inconsistent. To compare the literature international consensus is required.