Oral Virtual Presentation (Virtual only) ESA-SRB-ANZBMS 2021

Skeletal Age:  a new score for fracture risk assessment (#222)

Thach Tran 1 2 , Thao Ho-Le 1 , Dana Bliuc 1 , Bo Abrahamsen 3 4 , Louise Hansen 5 , Peter Vestargaard 6 7 8 , Jacqueline Center 1 2 9 , Tuan Nguyen 1 2 9 10
  1. Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
  2. Faculty of Medicine, University of New South Wales, Sydney, Australia
  3. Department of Medicine, Holbak Hospital, Holbak , Denmark
  4. Department of Clinical Research, Odense Patient Data Explorative Network, University of Southern Denmark, Odense, Denmark
  5. Kontraktenheden, North Denmark Region, Aalborg, Denmark
  6. Department of Clinical Endocrinology, Aalborg University Hospital, Aalborg, Denmark
  7. Department of Clinical Medicine, Aalborg University, Aalborg, Denmark
  8. Steno Diabetes Center , North Jutland, Denmark
  9. Clinical School, St Vincent's Hospital, Sydney, Australia
  10. School of Biomedical Engineering, University of Technology Sydney, Sydney, NSW, Australia

Many fragility fractures are associated with reduced life expectancy, which is usually not part of the doctor-patient discussion about fracture risk. We propose a new score called “Skeletal Age” to define the relationship between fracture and mortality for such a discussion. This study sought to estimate Skeletal Age based on risk factors.

Skeletal Age was defined as the age of an individual's skeleton resulting from a fragility fracture. Thus, for an individual with a fracture associated with increased mortality risk, the Skeletal Age would be expected to be higher than the individual's chronological age. We first used the Gompertz law of mortality to transform the hazard ratio of mortality for each fracture site into life expectancy as a result of a fracture. The difference between life expectancy associated with a fracture and population life expectancy is the loss of life years. Skeletal Age is then operationally defined as an individual's current age plus the years of life expectancy lost. This study used the Danish nationwide registry-based data including all individuals aged 50+ years.

During a median follow-up of 14.1 years (IQR:5.5-16.0), 95,372 men and 212,498 women sustained an incident fracture followed by 41,017 and 81,727 deaths, respectively. On average, a fragility fracture was associated with 1 to 3 years of life lost, with greater loss being observed in men and younger patients. Hip and proximal fractures, but not distal fractures, were associated with a substantial loss in life expectancy. For example, 60-year man with a hip fracture was calculated as having a skeletal age of 64.5 years (i.e., 4.5 years of life lost) (Table).

We propose that the Skeletal Age replaces relative risk as a score for conveying the risk of mortality associated with a fragility fracture, and for communicating the effect of fracture on life expectancy to patients.

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