Whether a Short or Long Alimentary Limb Influences Weight Loss in Gastric Bypass: a Systematic Review and Meta-Analysis.

Roux-en-Y gastric bypass, the most commonly performed procedure in bariatric surgery, still lacks a consensus on whether alimentary limb length (ALL) influences weight loss. Studies were identified by searching multiple electronic databases. Studies with enough data including body mass index (BMI) loss and percent excess weight loss (% EWL) were eligible. The statistical analysis was performed with Stata 14.0. In total, eight studies with 1714 patients were included. The meta-analysis suggested that short ALLs weakened the efficacy of Roux-en-Y gastric bypass in terms of BMI loss (standard mean deviation (SMD), - 0.33 [95% confidence intervals (CI), - 0.60, - 0.05], p = 0.021) with 3 years of follow-up and % EWL (SMD, - 0.17 [95% CI, - 0.31, - 0.04], p = 0.013) with 2 years of follow-up. The subgroup analysis demonstrated that the group with a BMI ≥ 50 kg/m2 had a significant SMD between the use of short and the standard ALLs (- 0.71 [95% CI, - 1.07, - 0.35], p = 0.000), while the subgroup with a BMI < 50 kg/m2 (SMD, - 0.29 [95% CI, - 0.78, 0.20], p = 0.247) did not. Compared with a standard ALL (130-150 cm), a short ALL (40-100 cm) may reduce the efficacy of the Roux-en-Y gastric bypass surgery, while a long ALL (170-250 cm) did not significantly improve the effects in terms of BMI loss and % EWL. In addition, a potential view of the meta-analysis indicated patients with a BMI < 50 kg/m2 might get more benefits with a short ALL, while those patients with a BMI ≥ 50 kg/m2 might benefit more from a standard ALL.