New Obesity Definition and Clinical Obesity Prevalence for Global Metabolic Bariatric Surgery
Authors' conclusion
This international, multicenter cross-sectional study found that the majority of MBS candidates met criteria for clinical obesity, while a substantial minority were classified as having preclinical obesity.
Study context
- Population
- Adults (≥18 years) undergoing primary metabolic bariatric surgery (MBS) (laparoscopic gastric bypass or SG), 2014–2025, at 4 centers in the UK, Spain, France and Brazil; revisional or multiple procedures excluded
- Participants
- 2,316 adults
- Exposure
- Clinical obesity vs preclinical obesity
- Clinical obesityn = 1,709
- Preclinical obesityn = 607reference
- Outcome
- Prevalence of clinical obesity
Methodological detailsmulticenter, 4 high-volume tertiary centers, Comparisons only within each cohort; no direct statistical comparisons between centers
- Multicenter
- 4 high-volume tertiary centers
- Comparisons only within each cohort; no direct statistical comparisons between centers
Main finding
As reported in the abstract
Observational data: associations, not effects.
Secondary outcomes
Age, UK cohort
P < 0.001
Age, French cohort
P < 0.001
Age, Spanish cohort
P < 0.001
Age, Brazilian cohort
P < 0.001
Median
| Outcome | Clinical obesity | Preclinical obesity | P value |
|---|---|---|---|
| ASA classification, UK cohort | 3 (IQR 2–3) | 2 (IQR 2–3) | P < 0.001 |
| ASA classification, French cohort | 3 (IQR 3–3) | 2 (IQR 2–3) | P < 0.001 |
| ASA classification, Spanish cohort | 2 (IQR 2–3) | 2 (IQR 1–2) | P < 0.001 |
| ASA classification, Brazilian cohort | 2 (IQR 2–2) | 2 (IQR 2–2) | P = 0.02 |
| Framingham risk score, Spanish cohort | 1.31 (IQR 0.20–4.34) | 0.20 (IQR 0.20–1.68) | P < 0.001 |
| Framingham risk score, Brazilian cohort | 1.57 (IQR 0.20–5.28) | 0.20 (IQR 0.20–0.20) | P < 0.001 |
| Framingham risk score, French cohort | 8.00 (IQR 3.00–13.00) | 2.00 (IQR 1.00–4.00) | P < 0.001 |
| Charlson Comorbidity Index, UK cohort | 1 (IQR 0–2) | 0 (IQR 0–0) | P < 0.001 |
| Charlson Comorbidity Index, Spanish cohort | 1 (IQR 0–1) | 0 | P < 0.001 |
| Charlson Comorbidity Index, Brazilian cohort | 1 (IQR 1–3) | 1 (IQR 0–1) | P < 0.001 |
Body mass index (BMI)
- Mean (SD) BMI ranged from 40.2 (4.9) (preclinical, Brazilian cohort) to 48.5 (9.0) (preclinical, UK cohort); BMI levels and category distributions (<40, 40-49, ≥50) similar between clinical and preclinical obesity
Safety
30-day major postoperative complications (Clavien-Dindo grade ≥3), French cohort
P = 0.04
Original publication
New Obesity Definition and Clinical Obesity Prevalence for Global Metabolic Bariatric Surgery. JAMA Netw Open. Published 3 August 2026. doi:10.
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