New Studies Confirm Body Mass Index and Family History Are Two Key Predictors of Fracture Risk

Two recently published meta-analyses provide compelling evidence that body mass index and family history of fracture are strong, independent predictors of future fracture risk. These findings come from an effort to update the most widely used fracture risk calculator, FRAX. The FRAX risk assessment tool and other algorithms are used to predict who is at greatest risk for hip fractures or major osteoporotic fractures (hip, spine, forearm, or shoulder).

The first study, entitled “Body mass index and subsequent fracture risk: a meta-analysis,” and published in the Journal of Bone and Mineral Research, is the largest analysis of adults across multiple countries. It confirms that BMI is a powerful independent predictor of fracture risk across populations, ages, and sexes, based on data from 1,667,922 men and women from 63 cohorts across 32 countries.

Researchers found that being underweight (a BMI below 18.5) is consistently linked to higher fracture risk for both women and men, with the effect slightly stronger in men. Maintaining a healthy or moderately higher weight (BMI between 25.0 and 29.9) can offer some protection, but hip fractures remain a concern for underweight adults at any age. Over time, the apparent advantage of being overweight or obese largely disappears once bone mineral density — a measure of bone strength — is taken into consideration.  

“Our findings show that body weight isn’t just about metabolism or heart health — it’s a crucial factor in bone health as well. Both underweight and overweight individuals face fracture risks that we cannot ignore, highlighting the importance of maintaining a healthy weight for bone health,” said Douglas P. Kiel, MD, MPH, director of the Musculoskeletal Research Center and senior scientist at the Hinda and Arthur Marcus Institute for Aging Research at Hebrew SeniorLife.  

Along with statistician Alyssa B. Dufour, PhD, associate scientist at the Marcus Institute, Kiel contributed data for the two publications from the Framingham Osteoporosis Study. “This large-scale study provides the strongest evidence yet that BMI should be a core component of how we assess fracture risk worldwide,” he noted.

The second study, “Family history of fracture and fracture risk: a meta-analysis to update the FRAX® risk assessment tool,” published in Osteoporosis International, confirmed that family history of fracture is a major risk factor for future fractures, independent of bone mineral density and other established predictors such as gender.

A family history of fracture is confirmed as a significant bone mineral density-independent predictor of future fracture risk. While parental hip fracture appears to be the strongest factor for future hip fracture, a family history of other fractures might be appropriate for inclusion in future iterations of the FRAX tool.

Based on 350,542 men and women, across 42 cohorts and 29 countries, researchers found that not only parental hip fractures, but also parental fractures at other sites and sibling fractures are associated with significantly increased risk across all fracture outcome categories, with a stronger relationship with future hip fracture.

Associations were slightly reduced but remained significant when additionally adjusted for bone mineral density and did not vary by baseline offspring age, follow-up time, or parent affected. In a more limited analysis, parental or sibling history of any fracture showed similar associations to those observed with parental history of hip fracture.

“We’ve long known that family history matters, but this study demonstrates just how broad and powerful that effect is,” said Kiel. “A simple question about fractures in parents or siblings could uncover hidden risks that bone density scans alone may miss. This evidence should guide updates to the FRAX tool and clinical practice alike. That means patients should share family fracture history, including that of siblings, with providers, as it may meaningfully influence care and prevention strategies. Additionally, while FRAX currently includes only parental hip fracture, these findings strongly support expanding family history inputs to include parental non-hip fractures and sibling fractures.”

Kiel also noted that, “Together, these two studies jointly underscore that fracture risk is multifactorial — not simply a question of how dense one’s bones are, but also who one is, what one weighs, and what one’s family history has been. When we include both BMI and family history in risk prediction, we sharpen our ability to identify those truly at risk — which means better prevention, earlier intervention, and more personalized care.”

In addition to Kiel and Dufour’s contributions, other participating institutions in the BMI meta-analysis include: Aarhus University; Australian Catholic University; Boston University School of Medicine; Catalan Institute of Health; Deakin University; Duke-NUS Medical School; Erasmus University Medical Center; Garvan Institute of Medical Research in Sydney; Hospital del Mar Medical Research Institute in Barcelona; Hospital Universitari de Bellvitge; Keio University; Kinki University; Lund University; McGill University; Medical University of Graz; National Heart Lung Blood Institute; National Institute on Aging; Norwegian University of Science and Technology; Oregon Health & Science University; Sahlgrenska University Hospital; Tel Aviv University; Tehran University of Medical Sciences; The Chinese University of Hong Kong; Tufts University; Umeå University in Sweden; University of Alabama at Birmingham; University of Barcelona; University of Bergen; University of Bern; University of Cambridge; University of California Los Angeles; University of California San Francisco; University of Eastern Finland; University of Geneva; University of Gothenburg; University of Greifswald; University of Groningen; University of Iceland; University of Lausanne; University of Liège; University of Lisbon; University of Lyon; University of Manchester; University of Manitoba; University of Melbourne; University of Oulu; University of Paris; University of Pittsburgh; University of Sheffield; University of Southampton; University of Southern Denmark; University of Strathclyde; University of Tasmania; University of Tokyo; University of York; University of Zurich; Uppsala University; and the VU University Medical Center.

In addition to Kiel and Dufour’s contributions, family history meta-analysis participating institutions include: Aarhus University; Australian Catholic University, Melbourne; Boston University School of Medicine; Catalan Institute of Health; Deakin University; Duke-NUS Medical School; Erasmus University Medical Center; Garvan Institute of Medical Research; Hospital del Mar Medical Research Institute; Hospital Universitari de Bellvitge; Kinki University; Lund University; Mayo Clinic; McGill University; Medical University of Graz; National Heart Lung Blood Institute; National Institute on Aging; Norwegian University of Science and Technology; Oregon Health & Science University; Sahlgrenska University Hospital; Tel Aviv University; Tehran University of Medical Sciences; The Chinese University of Hong Kong; Tufts University; Umeå University; University of Alabama at Birmingham; University of Barcelona; University of Bern; University of Bergen; University of Cambridge; University of California, Los Angeles; University of California, San Francisco; University of Coimbra, Portugal; University of Eastern Finland; University of Geneva; University of Gothenburg; University of Greifswald; University of Groningen; University of Iceland; University of Lausanne; University of Liège; University of Lyon; University of Manchester; University of Manitoba; University of Melbourne; University of Oulu; University of Paris; University of Pittsburgh; University of Rome; University of Sheffield; University of Southampton; University of Southern Denmark; University of Strathclyde; University of Tasmania; University of Tokyo; University of Zurich; Uppsala University; VU University Medical Center.

About Hebrew SeniorLife
Hebrew SeniorLife, an affiliate of Harvard Medical School, is a national senior services leader uniquely dedicated to rethinking, researching, and redefining the possibilities of aging. Hebrew SeniorLife cares for more than 4,500 seniors a day across seven campuses throughout Greater Boston. Locations include: Hebrew Rehabilitation Center-Boston and Hebrew Rehabilitation Center-NewBridge in Dedham; NewBridge on the Charles, Dedham; Orchard Cove, Canton; Simon C. Fireman Community, Randolph; Center Communities of Brookline, Brookline; Jack Satter House, Revere; and Leyland Community, Dorchester. Founded in 1903, Hebrew SeniorLife also conducts influential research into aging at the Hinda and Arthur Marcus Institute for Aging Research, which has a portfolio of more than $98 million, making it one of the largest gerontological research facilities in the U.S. in a clinical setting. It also trains more than 500 geriatric care providers each year. For more information about Hebrew SeniorLife, follow us on our blog, Facebook, Instagram, Threads, and LinkedIn.