Randomised controlled trialindependent cross-checkabstract checked I-BAR-126 standard review
Trial: bone after bypass vs sleeve
Bone Mineral Density and Turnover After Sleeve Gastrectomy and Gastric Bypass: A Randomized Controlled Trial (Oseberg).
Overview
Hofsø et al.. J Clin Endocrinol Metab 2021 · PMID 33150385 · DOI 10.1210/clinem/dgaa808
Hip and spine bone density fell more after bypass than 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?
Bone effects RYGB vs SG
- How was the study done?
RCT
- How many people, animals or samples were studied?
92
- What was actually found?
More bone loss after bypass
- How large was the observed effect?
Spine -4.2% difference
- What do the results mean in everyday life?
Bypass is harder on bone
- What are the study's limitations?
Small, short
- What does it say about Elawady's specific claim?
Refines the claim
- Do the results apply to Germany and Europe?
Directly European
- What can explicitly not be concluded from this study?
Fracture risk
Scientific in-depth review
1. Full reference
- Authors
- Hofsø et al.
- Journal
- J Clin Endocrinol Metab
- Year
- 2021
- Identifier
- PMID 33150385 DOI 10.1210/clinem/dgaa808
- 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
Do sleeve gastrectomy and gastric bypass differ in BMD and bone turnover at 1 year?
3. Study design and population
- Study design
- Randomised controlled trial – Randomised controlled trial (Oseberg), bone secondary outcomes at 1 year
- Population
Patients with severe obesity and type 2 diabetes
- Country
Norway
- Period
1-year follow-up
- Sample size
92 analysed (44 RYGB, 48 SG)
- Inclusion and exclusion criteria
Oseberg trial participants
4. Methods and endpoints
- Exposure / intervention
RYGB
- Comparator
SG
- Endpoints
aBMD (femoral neck, hip, spine, total body); P1NP, CTX-1
- Statistical methods
Between-group differences
5. Actual results
- Results
Femoral neck, total hip and lumbar spine aBMD decreased more after RYGB than SG: differences -2.8% (-4.7 to -0.8), -3.0% (-5.0 to -0.9), -4.2% (-6.4 to -2.1); total body -0.5% (NS). P1NP and CTX-1 increases ~100% higher after RYGB. Effects linked to procedure, not weight change.
- Absolute risks
not applicable
- Authors' conclusion
RYGB was associated with greater BMD reduction and bone turnover increase than SG, suggesting greater skeletal fragility after RYGB.
6. Strengths
- Randomised
- Blinded
7. Weaknesses
- Small; 1-year only
- Secondary outcome
8. Risk of bias
- Orienting tool
- RoB 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- low
- Rationale
Randomised, triple-blind.
9. Assessment of the statistical interpretation
Between-group differences with CIs.
10. Relevance to the specific claim
Randomised evidence that bone loss is larger after bypass than sleeve.
11. Independent contrary findings
Within-group sleeve change not in abstract.
12. Transferability to Germany and Europe
Norwegian.
13. Overall methodological judgement
Supports procedure-dependence of bone loss.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | low |
| Precision of results | low |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Fractures.
15. Linked fact checks
- Bariatric surgery causes measurable hip and spine bone loss (and fracture risk). – Studies with mixed or unclear results
- 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 contradicting or limiting the claim