Fracture distribution in postmenopausal women: a FRISBEE sub-study

Summary We registered 1336 incident-validated fractures in a prospective cohort of 3560 postmenopausal (60–85 years) Belgian women (mean follow-up of 9.1 years). The increase of fracture incidence with age varied widely depending on the fracture site and was significantly steeper for central than for peripheral fractures (e.g., not significant for the ankle). Introduction The epidemiology of fracture sites other than MOFs has been less studied. We examined the incidence of fractures according to their sites in a prospective cohort of postmenopausal Belgian women. Methods Three thousand five hundred sixty postmenopausal women, aged 60–85 years old, were recruited from 2007 to 2013 and surveyed yearly (FRISBEE). The number of validated incident fractures was recorded and analyzed in relation to age and the fracture site. Results One thousand three hundred thirty-six fractures were recorded after a mean follow-up of 9.1 years. Seven hundred fifty-six fractures (57%) were MOFs and 580 (43%) non-MOFs, while 813 (61%) were central and 523 (39%) peripheral. The increase of fracture incidence with age differed between fracture sites and was steeper for central than for peripheral fractures. The ratio of MOFs to non-MOFs increased significantly with age, from 1.10 (95% CI: 0.83–1.45) for the 60–69 to 1.69 [1.42–2.01] for the 80–89-year subgroup ( P = 0.017). This was also true for central versus peripheral fracture. We differentiated three groups of fracture incidence evolution with age: fractures with a mean increase/decade (compared to the 60–69 age group) of less than 1.5, 1.5–2.0, and 2.0–3.0. The lowest increase was seen for most peripheral fractures, whereas the greatest increase included hip, scapula, pelvis, ribs, and spine fractures. Conclusion The increase of fracture incidence with age varied widely depending on the fracture site, and the ratio of MOFs to non-MOFs rose significantly with age. Some peripheral fractures, such as the ankle, did not increase significantly with age, suggesting that bone fragility does not play a major role in their occurrence.