Osteoporosis International

, Volume 16, Issue 11, pp 1330–1338

Body mass index as a predictor of fracture risk: A meta-analysis

  • C. De Laet
  • J. A. Kanis
  • A. Odén
  • H. Johanson
  • O. Johnell
  • P. Delmas
  • J. A. Eisman
  • H. Kroger
  • S. Fujiwara
  • P. Garnero
  • E. V. McCloskey
  • D. Mellstrom
  • L. J. Melton3rd
  • P. J. Meunier
  • H. A. P. Pols
  • J. Reeve
  • A. Silman
  • A. Tenenhouse
Original Article

DOI: 10.1007/s00198-005-1863-y

Cite this article as:
De Laet, C., Kanis, J.A., Odén, A. et al. Osteoporos Int (2005) 16: 1330. doi:10.1007/s00198-005-1863-y

Abstract

Low body mass index (BMI) is a well-documented risk factor for future fracture. The aim of this study was to quantify this effect and to explore the association of BMI with fracture risk in relation to age, gender and bone mineral density (BMD) from an international perspective using worldwide data. We studied individual participant data from almost 60,000 men and women from 12 prospective population-based cohorts comprising Rotterdam, EVOS/EPOS, CaMos, Rochester, Sheffield, Dubbo, EPIDOS, OFELY, Kuopio, Hiroshima, and two cohorts from Gothenburg, with a total follow-up of over 250,000 person years. The effects of BMI, BMD, age and gender on the risk of any fracture, any osteoporotic fracture, and hip fracture alone was examined using a Poisson regression model in each cohort separately. The results of the different studies were then merged. Without information on BMD, the age-adjusted risk for any type of fracture increased significantly with lower BMI. Overall, the risk ratio (RR) per unit higher BMI was 0.98 (95% confidence interval [CI], 0.97–0.99) for any fracture, 0.97 (95% CI, 0.96–0.98) for osteoporotic fracture and 0.93 (95% CI, 0.91–0.94) for hip fracture (all p <0.001). The RR per unit change in BMI was very similar in men and women ( p >0.30). After adjusting for BMD, these RR became 1 for any fracture or osteoporotic fracture and 0.98 for hip fracture (significant in women). The gradient of fracture risk without adjustment for BMD was not linearly distributed across values for BMI. Instead, the contribution to fracture risk was much more marked at low values of BMI than at values above the median. This nonlinear relation of risk with BMI was most evident for hip fracture risk. When compared with a BMI of 25 kg/m2, a BMI of 20 kg/m2 was associated with a nearly twofold increase in risk ratio (RR=1.95; 95% CI, 1.71–2.22) for hip fracture. In contrast, a BMI of 30 kg/m2, when compared with a BMI of 25 kg/m2, was associated with only a 17% reduction in hip fracture risk (RR=0.83; 95% CI, 0.69–0.99). We conclude that low BMI confers a risk of substantial importance for all fractures that is largely independent of age and sex, but dependent on BMD. The significance of BMI as a risk factor varies according to the level of BMI. Its validation on an international basis permits the use of this risk factor in case-finding strategies.

Keywords

BMIFracturesMeta-analysisOsteoporosisProspective studiesRisk

Copyright information

© International Osteoporosis Foundation and National Osteoporosis Foundation 2005

Authors and Affiliations

  • C. De Laet
    • 1
  • J. A. Kanis
    • 2
  • A. Odén
    • 3
  • H. Johanson
    • 3
  • O. Johnell
    • 4
  • P. Delmas
    • 5
  • J. A. Eisman
    • 6
  • H. Kroger
    • 7
  • S. Fujiwara
    • 8
  • P. Garnero
    • 9
  • E. V. McCloskey
    • 2
  • D. Mellstrom
    • 10
  • L. J. Melton3rd
    • 11
  • P. J. Meunier
    • 12
  • H. A. P. Pols
  • J. Reeve
    • 13
  • A. Silman
    • 14
  • A. Tenenhouse
    • 15
  1. 1.Scientific Institute of Public HealthBrusselsBelgium
  2. 2.WHO Collaborating Centre for Metabolic Bone DiseasesUniversity of Sheffield Medical SchoolSheffieldUK
  3. 3.Consulting StatisticianGothenburgSweden
  4. 4.Department of OrthopaedicsMalmö General HospitalMalmöSweden
  5. 5.INSERM Unité 149VillejuifFrance
  6. 6.Bone and Mineral Research Program, Garvan Institute of Medical ResearchSt Vincent’s Hospital and University of New South WalesSydneyAustralia
  7. 7.Department of Surgery, Bone and Cartilage Research UnitKuopio University HospitalKuopioFinland
  8. 8.Department of Clinical StudiesRadiation Effects Research FoundationHiroshimaJapan
  9. 9.INSERM Unité 403LyonFrance
  10. 10.Department of Geriatric MedicineGoteborg UniversityGothenburgSweden
  11. 11.Division of EpidemiologyMayo ClinicRochesterUSA
  12. 12.INSERM Unit 403, Faculty R LaennecLyonFrance
  13. 13.Strangeway’s Research LaboratoryCambridgeUK
  14. 14.ARC Epidemiology UnitUniversity of ManchesterManchesterUK
  15. 15.Division of Bone MetabolismThe Montreal General HospitalMontrealCanada