Two-Year Outcomes of Sleeve Gastrectomy with Dual Pathways: A Single-Center Experience of B-TB and SASI Procedures

Technical Summary: Two-Year Outcomes of Sleeve Gastrectomy with Dual Pathways (B-TB vs. SASI)

Problem Statement
While Sleeve Gastrectomy (SG) is the most widely performed bariatric procedure globally, it faces limitations regarding mid-to-long-term weight regain and less potent remission of Type 2 Diabetes Mellitus (T2DM) compared to Roux-en-Y Gastric Bypass (RYGB). To address these drawbacks, surgeons have developed composite procedures that combine SG with intestinal bypass maneuvers. Two such emerging techniques are Sleeve Gastrectomy with Braun Anastomosis Transit Bipartition (B-TB) and Single Anastomosis Sleeve Ileal (SASI). B-TB adds a Braun anastomosis and an ileo-ileal anastomosis to create a diversion pathway, while SASI involves an end-to-side anastomosis between the ileum and the gastric staple line. Despite their theoretical advantages, clinical research on these procedures remains in early stages, consisting primarily of small case series. Crucially, there is a lack of direct, head-to-head comparisons between B-TB and SASI regarding their 2-year efficacy and safety profiles.

Methodology
This study presents a single-center, retrospective analysis of 234 patients with obesity who underwent either B-TB ($n=127$) or SASI ($n=107$) between May 2021 and May 2023 at Baoji Hospital Affiliated to Xi'an Medical University.

• Patient Selection: Inclusion criteria included age 17–69, BMI $\ge$ 32.5 kg/m² (or $\ge$ 27.5 kg/m² with metabolic comorbidities), and primary bariatric surgery. Exclusion criteria included revision surgeries, severe organ dysfunction, malignancy, pregnancy, and incomplete follow-up data (<3 months).
• Surgical Technique: Both procedures began with a standard laparoscopic sleeve gastrectomy.
  • SASI: An end-to-side anastomosis was created between the ileum (approx. 300 cm proximal to the ileocecal valve) and the gastric staple line.
  • B-TB: A Braun anastomosis and an ileo-ileal anastomosis were added to the SG to establish a bowel diversion pathway resembling "transit bipartition."
• Data Collection: Patients were followed up at 6, 12, and 24 months. Outcomes measured included weight loss metrics (Total Weight Loss [%TWL], Excess Weight Loss [%EWL]), BMI, remission rates of comorbidities (T2DM, dyslipidemia, hypertension, obstructive sleep apnea [OSA]), and complication rates (graded by Clavien-Dindo classification).
• Statistical Analysis: Continuous variables were compared using Welch's t-test, and categorical variables using $\chi^2$ or Fisher's exact tests. To control for multiple comparisons, a step-down Bonferroni–Holm correction was applied.

Key Results

• Weight Loss Efficacy: Both procedures achieved substantial weight loss at 6 and 12 months, with outcomes plateauing after 12 months.
  • At 12 months, the SASI group demonstrated statistically superior weight loss compared to B-TB: %TWL was $35.26 \pm 6.46\%$ vs. $31.12 \pm 7.36\%$ ($P=0.026$ adjusted), and %EWL was $104.76 \pm 21.41\%$ vs. $93.72 \pm 22.46\%$ ($P=0.032$ adjusted).
  • At 24 months, these differences disappeared; no statistically significant differences were observed between the two groups in any weight-loss parameter.
• Comorbidity Resolution:
  • T2DM: Both procedures achieved remission rates exceeding 90% with no significant intergroup difference.
  • Dyslipidemia & Hypertension: Remission rates were comparable between groups (approx. 77–80% for dyslipidemia; approx. 72% for hypertension).
  • Obstructive Sleep Apnea (OSA): The SASI group showed a significantly higher complete remission rate (91.21%) compared to B-TB (77.39%) ($P=0.031$ adjusted). Conversely, the B-TB group had a significantly higher improvement rate (22.61%) compared to SASI (8.79%) ($P=0.045$ adjusted). The authors attribute the superior remission in SASI to its greater mid-term weight loss efficacy.
• Safety: Both procedures demonstrated favorable safety profiles with no severe adverse events or mortalities.
  • Overall complication rates were 11.02% (B-TB) and 13.08% (SASI) ($P=0.623$).
  • Early (30-day) complication rates were 5.51% (B-TB) and 4.67% (SASI).
  • Specific complications included anastomotic leaks (resolved conservatively), intestinal obstructions (managed conservatively), and gastroesophageal reflux (Grade B).

Significance and Claims
The authors conclude that both B-TB and SASI are safe and effective metabolic and bariatric surgical procedures. The study highlights that while SASI offers superior mid-term (12-month) weight loss and OSA remission, likely due to more complete biliopancreatic diversion, these advantages diminish over time, resulting in comparable long-term (24-month) efficacy between the two groups.

The paper claims that the choice between these procedures should be guided by individual patient characteristics and specific comorbidities rather than a single superior option. For instance, SASI may be preferred for patients prioritizing maximum mid-term weight loss or OSA resolution, while B-TB may be considered for those where preserving a more intact gastrointestinal anatomical configuration is desired. The study emphasizes that both procedures successfully combine the operational simplicity of SG with enhanced metabolic efficacy, providing evidence-based guidance for clinical decision-making in the absence of randomized controlled trials.