Conversion of gastric sleeve to Roux-en-Y gastric bypass: overall outcomes and predictors of below-average weight loss.

Background: Conversion of sleeve gastrectomy (SG) to Roux-en-Y gastric bypass (RYGB) has been utilized to promote further weight loss, but results are variable in available literature.

Objectives: To evaluate outcomes of SG to RYGB conversion for weight loss and to identify predictors of below-average weight loss.

Setting: University-affiliated hospital, United States.

Methods: Chart review was performed of our patients who underwent SG to RYGB conversion from November 1, 2013, to November 1, 2020. Primary outcomes were below-average percent excess weight loss (%EWL) at 1 and 2 years. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for preconversion demographics to evaluate their relationship to the primary outcome.

Results: Sixty-two patients underwent conversion from SG to RYGB with weight loss as a goal. One-year data was available for 47 patients. The average %EWL at 1 year was 41.5%. Twenty-six patients had below-average %EWL at 1 year. Interval to conversion <2 years (OR = 4.41, 95% CI [1.28,15.17], P = .019) and preconversion body mass index (BMI) >40 (OR = 4.00, 95% CI [1.17,13.73], P = .028) were statistically significant predictors of below-average 1-year %EWL. Two-year data was available for 36 patients. The average %EWL at 2 years was 30.8%. Seventeen patients had below-average %EWL at 2 years. Evaluated demographics were not statistically significant predictors of below-average 2-year %EWL.

Conclusions: Following SG to RYGB conversion, %EWL outcomes are lower at 1 year (41.5%) and 2 years (30.8%) than reported values for primary RYGB. Interval to conversion <2 years and preconversion BMI >40 are predictors of below-average 1-year weight loss after conversion.