One Anastomosis Gastric Bypass (OAGB) with a 150-cm Biliopancreatic Limb (BPL) Versus a 200-cm BPL, a Systematic Review and Meta-analysis

**Background:** One anastomosis gastric bypass (OAGB) is a widely accepted bariatric procedure combining malabsorption with restriction. However, no optimal biliopancreatic limb (BPL) length has been standardized. While a 200-cm BPL is most commonly used, some advocate for a 150-cm BPL to minimize nutritional deficiencies while maintaining acceptable weight loss and comorbidity remission. This systematic review and meta-analysis aimed to assess the impact of OAGB with a 150-cm versus a 200-cm BPL on weight loss, comorbidity remission, and adverse nutritional effects.

**Methods:** The review followed PRISMA guidelines and searched EMBASE, PubMed Central, and Google Scholar using MeSH terms related to OAGB and BPL lengths. Inclusion criteria were original English-language articles comparing 150-cm and 200-cm BPL lengths in OAGB patients. Reviews, commentaries, and studies without direct comparison were excluded. Eight studies published from 2019 to 2022 were included, all retrospective analyses of prospectively registered hospital databases. The total population was 2,599 patients: 1,100 (42.3%) with 150-cm BPL, 1,336 (51.4%) with 200-cm BPL, and 111 (4.3%) with other lengths excluded from analysis. Follow-up periods ranged from 10 to 44.87 months, with a median of 24 months in most studies. Sample sizes ranged from 155 to 784 patients. The primary outcome was weight loss difference; secondary outcomes were comorbidity remission and nutritional deficiency rates. Meta-analysis was performed using RevMan version 5.4, with weighted mean differences for numerical data and odds ratios with 95% CIs for categorical data. Heterogeneity was assessed using the I² statistic.

**Key Results:** The pooled analysis favored the 200-cm BPL for weight loss, with a statistically non-significant difference in excess weight loss percentage (EWL%; p=0.67) but a highly significant difference in total weight loss percentage (TWL%; p=0.009). No statistically significant differences were found between groups for diabetes mellitus resolution (p=0.78) or improvement (p=0.2), nor for hypertension resolution (p=0.54) or improvement (p=0.24). Overall diabetes mellitus remission occurred in 92.6% of patients with 150-cm BPL versus 86.4% with 200-cm BPL. Hypertension remission (complete resolution or improvement) occurred in 79.6% of 150-cm BPL patients and 74.1% of 200-cm BPL patients. Significantly higher rates of ferritin deficiency (p=0.002) and folate deficiency (p=0.04) were found in the 200-cm BPL group. No statistically significant differences were observed for deficiencies in albumin, total protein, vitamin B12, vitamin D, or parathyroid hormone. Reoperation rates were described in 4 studies and showed no significant difference between groups (p=0.13).

**Clinical Implications:** This meta-analysis, the first to directly compare 150-cm versus 200-cm BPL in OAGB within the IFSO-recommended window, demonstrates that a 200-cm BPL provides superior weight loss (mean TWL% difference of 2.6% and mean EWL% difference of 0.9%) at the cost of higher nutritional deficiency rates, particularly for ferritin and folate. Comorbidity remission rates were comparable between groups. The findings suggest that if a 200-cm BPL is selected, proper patient selection and strict postoperative nutritional surveillance are essential. Limitations include the small number of included studies, lack of standardized follow-up periods, retrospective design of all included studies, and inclusion of one poster abstract. No randomized controlled trials were available. The clinical significance of the modest weight loss advantage of the 200-cm BPL is questionable and must be weighed against the increased nutritional risk.