Skeletal Age as an Alternative Way to Present the Mortality Risk Following Fracture Due to Osteoporosis
Bone mineral density decreases with age, a growing imbalance between the activity of osteoblasts (depositing bone) and osteoclasts (breaking down bone). This leads eventually to meaningful risk of fracture and osteoporosis. Suffering bone injury due to bone weakness in later life is a spiral downwards into debilitating incapacity, and comes with a significantly raised risk of mortality. Here, researchers run the numbers to present the increased mortality risk following fracture as an adjustment to skeletal age, in the hope of increasing the use of existing therapies for osteoporosis.
Osteoporosis is a 'silent disease' which often has no immediate symptoms but gradually weakens bones and makes them more likely to break. A bone fracture caused by osteoporosis in people over the age of 50 is linked to long-term health decline and in some cases, even early death. However, poor communication of the mortality risk to patients has led to a low uptake of treatment, resulting in a crisis of osteoporosis management. The impact of a fracture on life expectancy is typically conveyed to patients and the public in terms of probability (how likely something is to occur) or the relative risk of death compared to other groups. However, statements such as "Your risk of death over the next 10 years is 5% if you have suffered from a bone fracture" can be difficult to comprehend and can lead to patients underestimating the gravity of the risk.
With the aim of devising a new way of conveying risks to patients, researchers analyzed the relationship between fracture and lifespan in over 1.6 million individuals who were 50 years of age or older. The findings showed that one fracture was associated with losing up to 7 years of life, depending on gender, age and fracture site. Based on this finding, researchers proposed the idea of 'skeletal age' as a new metric for quantifying the impact of a fracture on life expectancy. Skeletal age is the sum of the chronological age of a patient and the estimated number of years of life lost following a fracture. For example, a 60-year-old man with a hip fracture is predicted to lose an estimated 6 years of life, resulting in a skeletal age of around 66. Therefore, this individual has the same life expectancy as a 66-year-old person that has not experienced a fracture.
Skeletal age can also be used to quantify the benefit of osteoporosis treatments. Some approved treatments substantially reduce the likelihood of post-fracture death and translating this into skeletal age could help communicate this to patients. For instance, telling patients that "This treatment will reduce your skeletal age by 2 years" is easier to understand than "This treatment will reduce your risk of death by 25%".