Current tools for predicting fracture risk underestimate the risk in people with diabetes who have higher rates of fractures than the general population, often despite normal bone mineral density (BMD).

However the addition of information about the microarchitecture of bone to existing tools such as FRAX, can improve fracture prediction in people with diabetes.

Australian researchers have tested use of a trabecular bone score (TBS) and FRAX in a sample of more than 1,000 participants from the Geelong Osteoporosis Study.

The limbic asked Dr Kara Holloway, from Deakin University’s Centre for Innovation in Mental and Physical Health and Clinical Treatment, about the research and its translation.

TBS was lower in men and women with diabetes than their normoglycaemic peers, and particularly in people less than 65 years of age. There was no difference in BMD between the groups. What does this tell us about diabetes-related bone changes?

These results indicate that in individuals with diabetes, the amount of bone, as measured by bone mineral density, is not compromised, but rather the way that the bone is organised.

Bone strength is a combination of not only the bone mass, but also the geometry, microarchitecture and bone turnover.

The results of this study investigated the differences between bone microarchitecture, as measured by the trabecular bone score (TBS) and showed that the organisation, or structure, of the bone in individuals with diabetes is poorer than in those without diabetes.

The study also found TBS-adjusted FRAX scores were better able to distinguish fracture risk in people with diabetes than unadjusted FRAX scores. What are the clinical implications?

FRAX is a tool used by clinicians for calculating an individual’s risk of sustaining a hip or major osteoporotic fracture within the next 10 years. If a person meets a certain threshold (≥20% for major osteoporotic fracture and ≥3% for hip), then they are recommended for anti-fracture therapy.

However, in individuals with diabetes, FRAX has been shown to underestimate fracture risk and thus individuals who may require treatment are not identified.

FRAX has recently been updated to include an adjustment for TBS, and this study has shown that this adjusted score is better at identifying individuals with diabetes who are at a high risk for fracture.

Overall, this may influence treatment decisions and outcomes for individuals with diabetes.

 What are the barriers to incorporating TBS into fracture prediction? What else do we need to know?

TBS is determined retrospectively from lumbar spine DXA scans and thus no additional scans or measurements are necessary, making it simple, quick and easy for a DXA technologist to incorporate into their usual work.

However, TBS is still a new measurement, and technical aspects are still being investigated. For example, it is suggested that soft tissue thickness influences TBS results and it is currently recommended that it only be used for individuals with a BMI between 15 and 37 kg/m².

Additionally, TBS has not yet been approved for monitoring the efficacy of anti-fracture therapy and should only be used in conjunction with FRAX and bone mineral density assessments.

Further research is needed before TBS can be used separately from other methods of fracture risk assessment.

You can read the clinical paper published in Calcified Tissue International here.