Osteoporosis: assessing the risk of fragility fracture

Why this is important

Fracture risk is currently assessed opportunistically. GP records are now universally computerised and contain information that may be useful in identifying patients at high risk of fracture (for example, age, record of prescriptions, major diagnoses and previous fracture). A study is needed to assess whether people at higher risk can be identified by using risk assessment tools to obtain an estimate of risk based on pre-existing information and inviting people at highest risk for a clinical assessment and risk-factor estimation. This could result in a more effective and efficient use of staff time and health service resources than an opportunistic approach.

Why this is important

Because of concerns about rare but serious side effects of long-term anti-resorptive therapy, many physicians prescribe these drugs for a finite period of time, usually 3 to 5 years. Reassessment of fracture risk at the end of this treatment period is important, since some people remain at high risk of fracture and require continued treatment, whereas others may benefit from a 'drug holiday' for 1 or more years. Neither FRAX nor QFracture has been examined in patients who had treatment, and it is not known whether the ability of clinical risk factors with or without measurement of bone mineral density (BMD) to predict fracture risk is similar in patients who had or did not have treatment. There is therefore a need for prospective studies to investigate the predictive power of these tools to assess fracture risk in patients after a period of bone protective therapy.

Why this is important

If secondary osteoporosis is entered as a risk factor in FRAX, the algorithm assumes that the effect is mediated solely through effects on BMD. Input of BMD into the questionnaire in such patients will therefore generate the same fracture risk whether or not secondary osteoporosis is entered. However, it is likely that at least some causes of secondary osteoporosis (for example, inflammatory bowel disease) affect fracture risk by mechanisms that are partially independent of BMD and fracture risk may therefore be underestimated in such patients. There is therefore a need to investigate the accuracy of FRAX in predicting fracture risk in patients with causes of secondary osteoporosis other than rheumatoid arthritis and to establish whether their effect on fracture risk is mediated solely through effects on BMD.

Why this is important

The 10-year fracture risk as estimated by FRAX is calculated using clinical risk factors with or without BMD. The clinical risk factors are routinely available, making calculation of fracture risk possible at the time of consultation. However, refinement of a patient's 10‑year fracture risk using BMD requires assessment using dual‑energy X‑ray absorptiometry (DXA) scanning equipment.

Currently, there are no definitive studies in primary or secondary care evaluating whether the addition of BMD to FRAX improves the accuracy of the predicted fracture risk. There is a need for studies to examine whether adding BMD to FRAX results in the correct reclassification of patients from low risk to high risk (and vice versa). Furthermore, studies are also needed to evaluate the clinical usefulness (net benefit) of adding BMD to FRAX; that is, how many more patients are correctly classified as high risk (true positives) and low risk (true negatives).

Why this is important

Care home residents are at high risk of fragility fracture. This is probably related to increased age and frailty with multiple comorbidities, which increase fracture risk. There is also evidence that care home residents have lower BMD, with 70% assessed as having osteoporosis using densitometry criteria alone. However, tools such as FRAX and QFracture, which only estimate fracture risk up to the 9^th decade and use 10‑year fracture risk, may underestimate short-term risk in care home residents, who have a mean age of approximately 85 years and a life expectancy of less than 5 years.

A study is required to assess whether care home residents should have targeted fracture risk assessment and whether residents at higher risk of fracture can be identified, using FRAX or QFracture. This could result in a more effective and efficient strategy for fracture prevention, targeting health service resources on those at the very highest fracture risk.