Randomised controlled trialindependent cross-checkabstract checked★ key study I-BAR-142 in-depth review
Swiss trial: sleeve vs bypass after 10 years
Long-Term Outcomes of Laparoscopic Roux-en-Y Gastric Bypass vs Laparoscopic Sleeve Gastrectomy for Obesity: The SM-BOSS Randomized Clinical Trial.
Overview
Kraljevic et al.. JAMA Surg 2025 · PMID 39969869 · DOI 10.1001/jamasurg.2024.7052
After more than 10 years, 3 in 10 sleeve patients needed a conversion operation (for reflux or weight) vs about 1 in 20 after bypass; new reflux was more common after sleeve.
Does the study support the specific claim? Partly · Methodological quality: high
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Compare long-term SG and RYGB
- How was the study done?
RCT
- How many people, animals or samples were studied?
217
- What was actually found?
More conversions and de novo GERD after SG
- How large was the observed effect?
29.9% vs 5.5% conversions
- What do the results mean in everyday life?
Sleeve has more long-term reflux problems
- What are the study's limitations?
Attrition
- What does it say about Elawady's specific claim?
Supports reflux and bypass-preference parts
- Do the results apply to Germany and Europe?
Directly European
- What can explicitly not be concluded from this study?
Mortality differences
Scientific in-depth review
1. Full reference
- Authors
- Kraljevic et al.
- Journal
- JAMA Surg
- Year
- 2025
- Identifier
- PMID 39969869 DOI 10.1001/jamasurg.2024.7052
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref API
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract
2. Research question
How do SG and RYGB compare for weight, metabolic outcomes, reoperations, GERD and quality of life at >=10 years?
3. Study design and population
- Study design
- Randomised controlled trial – Multicentre randomised controlled trial (SM-BOSS), 10-year and longer follow-up
- Population
Patients with severe obesity (mean BMI 43.9)
- Country
Switzerland
- Period
Enrolment 2007-2011; last follow-up July 2023
- Sample size
217 randomised (107 SG, 110 RYGB); complete 10-y follow-up 65.4%
- Inclusion and exclusion criteria
4 Swiss bariatric centres
4. Methods and endpoints
- Exposure / intervention
Laparoscopic SG
- Comparator
Laparoscopic RYGB
- Endpoints
%EBMIL, %TWL, conversions, de novo GERD, comorbidities, QoL
- Statistical methods
ITT and per-protocol analyses
5. Actual results
- Results
ITT %EBMIL 60.6% (SG) vs 65.2% (RYGB), P=.29; per-protocol 56.1% vs 65.9%, P=.048; %TWL 25.5% vs 27.7% (P=.37). Conversion to different anatomy for insufficient weight loss or reflux 29.9% (SG) vs 5.5% (RYGB), P<.001. Significantly more de novo GERD after SG (P=.02).
- Absolute risks
About 30 in 100 sleeve patients had a conversion operation within 10+ years vs about 6 in 100 after bypass.
- Authors' conclusion
RYGB led to higher %EBMIL (per protocol) beyond 10 years with better GERD results; SG had significantly more conversions.
6. Strengths
- Randomised, multicentre, >10 y
7. Weaknesses
- 34.6% incomplete 10-y follow-up
- Small trial
8. Risk of bias
- Orienting tool
- RoB 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Attrition at 10 y.
9. Assessment of the statistical interpretation
Conversion difference large (29.9% vs 5.5%); GERD P value only in abstract.
10. Relevance to the specific claim
Long-term randomised evidence that sleeve causes more de novo reflux and many more conversion operations than bypass.
11. Independent contrary findings
Total weight loss similar.
12. Transferability to Germany and Europe
Swiss data; directly European.
13. Overall methodological judgement
High-quality support for reflux/conversion concern; supports bypass preference when reflux matters.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Hard outcomes.
15. Linked fact checks
- Sleeve gastrectomy substantially increases gastro-oesophageal reflux disease and erosive oesophagitis. – Studies supporting the claim
- Gastric bypass is preferable to sleeve gastrectomy (less reflux) and can fully treat type 2 diabetes; for patients who fail dieting, bypass rather than sleeve should be chosen (2021 statement). – Studies supporting the claim
- After sleeve gastrectomy reflux is inevitable, and patients must take acid-suppressing drugs for life. – Studies with mixed or unclear results