Body mass index and subsequent fracture risk: a meta-analysis to update FRAX
Authors' conclusion
Underweight is a risk factor for fracture in both men and women regardless of adjustment for BMD. However, while overweight/obesity appeared protective in base models, they became risk factors after additional adjustment for FN BMD, particularly in the Obese II category. This effect in the highest BMI categories was of greater magnitude in men than women.
Study context
- Population
- Men and women from 32 countries (63 cohorts), 16.0 million person-years of follow-up; 293,325 with FN BMD measured
- Participants
- 1,667,922 men63 cohorts
- Comparison
- WHO-defined BMI categories vs normal weight
- Outcome
- Incident osteoporotic, major osteoporotic and hip fracture
Methodological detailsinternational, extended Poisson model per cohort, inverse-variance weighted β-coefficients
- International
- Extended Poisson model per cohort
- Inverse-variance weighted β-coefficients
Pooled result
As reported in the abstract
Hip fracture, adjusted for age and follow-up time (BMD subset)
Each group vs normalEstimate (95% CI)
Underweight
HR (women) 2.35(2.10–2.60)
Underweight
HR (men) 2.45(1.90–3.17)
Obese II
HR (women) 0.66(0.55–0.80)
Obese II
HR (men) 0.91(0.66–1.26)
Further pooled results
| Outcome | Estimate | |
|---|---|---|
| Hip fracture, further adjusted for FN BMD T-scoreUnderweightvs Normal | HR (women) 1.69 (95% CI 1.47–1.96) | |
| Hip fracture, further adjusted for FN BMD T-scoreUnderweightvs Normal | HR (men) 1.46 (95% CI 1.00–2.13) | |
| Hip fracture, further adjusted for FN BMD T-scoreObese IIvs Normal | HR (women) 1.24 (95% CI 0.97–1.58) | |
| Hip fracture, further adjusted for FN BMD T-scoreObese IIvs Normal | HR (men) 1.70 (95% CI 1.06–2.75) | |
| 0.20.5125Ratio (log scale) |
Hip fracture, further adjusted for FN BMD T-score
- Protective effects of overweight and obesity attenuated; direction reversed to higher risk in Obese II in both sexes
Other fracture outcomes
- Results were similar for other fracture outcomes
Original publication
Body mass index and subsequent fracture risk: a meta-analysis to update FRAX. J Bone Miner Res. Published 8 August 2025. doi:10.
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