Meta-analysisindependent cross-checkabstract checked★ key study I-BAR-120 in-depth review
Meta-analysis: anaemia after sleeve
Prevalence of anemia and related nutrient deficiencies after sleeve gastrectomy: A systematic review and meta-analysis.
Overview
Nie et al.. Obes Rev 2023 · PMID 36323610 · DOI 10.1111/obr.13516
About 1 in 5 sleeve patients had anaemia 4-5 years after surgery, mostly from iron deficiency; B12 and folate deficiency stayed rare.
Does the study support the specific claim? Partly · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Track deficiencies after SG
- How was the study done?
Meta-analysis
- How many people, animals or samples were studied?
7,639
- What was actually found?
Anaemia rising to 18-25%
- How large was the observed effect?
Proportions
- What do the results mean in everyday life?
Iron checks and supplements matter after sleeve
- What are the study's limitations?
Observational
- What does it say about Elawady's specific claim?
Supports iron part; limits B12 part for sleeve
- Do the results apply to Germany and Europe?
Applicable
- What can explicitly not be concluded from this study?
Whether everyone is affected
Scientific in-depth review
1. Full reference
- Authors
- Nie et al.
- Journal
- Obes Rev
- Year
- 2023
- Identifier
- PMID 36323610 DOI 10.1111/obr.13516
- 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 common are anaemia and related nutrient deficiencies after sleeve gastrectomy over time?
3. Study design and population
- Study design
- Meta-analysis – Systematic review and meta-analysis of proportions
- Population
Patients after SG
- Country
Multinational
- Period
not stated in abstract
- Sample size
31 studies, 7,639 patients
- Inclusion and exclusion criteria
Studies reporting anaemia/nutrient deficiency after SG
4. Methods and endpoints
- Exposure / intervention
Sleeve gastrectomy
- Comparator
Baseline
- Endpoints
Anaemia, ferritin, iron, B12, folate deficiency
- Statistical methods
Pooled prevalence by time point; subgroup analysis
5. Actual results
- Results
Anaemia 7% at baseline, 10% at 12 mo, 12% at 24 mo, 25% at 36 mo, 20% at 48 mo, 18% at 60 mo. Ferritin deficiency 6% -> 27% at 60 mo; serum iron deficiency 13% -> 6% at 24 mo -> 20% at 60 mo. B12 and folate deficiency remained low. Risk factors: age <=40, preoperative anaemia, insufficient iron supplementation.
- Absolute risks
Anaemia about 1 in 5 at 5 years after sleeve.
- Authors' conclusion
SG is associated with increased long-term anaemia and decreasing iron stores; guideline iron doses may be insufficient; stricter monitoring needed.
6. Strengths
- Sleeve-specific
- Time course
7. Weaknesses
- Observational, heterogeneous
- Supplement adherence varies
8. Risk of bias
- Orienting tool
- AMSTAR 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Abstract only.
9. Assessment of the statistical interpretation
Prevalences; no control group.
10. Relevance to the specific claim
Shows iron deficiency/anaemia rises after sleeve over years, while B12/folate deficiency stays low - partly supports and partly limits the claim.
11. Independent contrary findings
Deficiency is not universal and is treatable.
12. Transferability to Germany and Europe
International.
13. Overall methodological judgement
Moderate evidence that iron deficiency is a real long-term issue after sleeve.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| 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
Optimal iron dosing.
15. Linked fact checks
- Bariatric surgery causes lifelong deficiencies of iron, B12, vitamin D, calcium and protein, requiring lifelong supplements. – Studies supporting the claim
- Sleeve gastrectomy is a physiologically wrong operation and a 'transgression against God's creation', because the stomach is not a bag but an endocrine, muscular and immune organ whose functions are lost. – Studies with mixed or unclear results