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LSG is the most common Bariatric procedure in the US; however, the frequency of conversion to RYGB is unknown. The primary objective of the study was to determine both the prevalence and factors associated with conversion to RYGB. The secondary objective was to evaluate post-conversion weight loss outcomes.


A retrospective analysis of all LSG from 2011-2020 was done. Kaplan-Meier analysis was utilized to estimate the conversion rate over time after LSG. Cox regression was utilized to identify predictors of future conversion.


Of 875 LSGs, 46 were converted to RYGB for refractory GERD. Median follow-up was 2.6 years. The 1-year conversion rate was 1.4%, increasing to 3.8%, 9.0% and 12.6% at 3, 5 and 7 years respectively. Female gender (HR=4.2, p=0.05) and age <55 (HR=3.5, p=0.04) were associated with greater chance of conversion. Asthma (HR=1.7, p=0.14) and GERD (HR=1.5, p=0.18) prior to LSG trended towards higher conversion but were not significant. Of those with BMI>35 at time of conversion, 18/25 had 1-year weight follow-up. Mean total body weight loss (TBWL) was 13.0% at the time of conversion. This subgroup had an additional 13.6% of TBWL 1-year after conversion to RYGB.


We found that conversion of LSG to RYGB increased with time to at least a 12.6% conversion rate at 7 years. Patients with GERD prior to LSG had a nonsignificant trend toward conversion, while younger patients and females had significantly higher rates of conversion. There may be additional weight loss benefit for patients converted to RYGB.