Osteoporosis, Fracture Prevention and Falls Risk Assessment
women who had sustained a distal radial fracture met the WHO diagnostic criteria for osteoporosis or osteopenia on a dual-energy X-ray absorptiometry (DXA) scan.13
In other more recent studies,14,15
which assessed changes in BMD in patients receiving steroid therapy, women receiving hormone antagonist therapy as well as men receiving hormone deprivation therapy; it was revealed that by the end of one year of therapy the prevalence of osteoporosis in the forearm (T-score below -2.5) was significantly higher (p<0.001) than its prevalence in both spine and hip, and that the association of BMD loss with fracture was site-specific. Therefore, in the majority of cases, a distal radial fracture in a post-menopausal woman should alert the treating physician that osteoporosis is very likely to be present. A thorough medical history, evaluation for contributing factors and aggressive treatment are highly indicated.
Getting the Risk Factors into the Equation In order for risk factors to be clinically useful in areas where BMD testing is available, they must be independent of BMD and modifiable by pharmaceutical intervention. Those factors that were validated by the WHO included BMD at the femoral neck, age, a prior fragility fracture, glucocorticoid exposure, parental history of hip fracture, current smoking, excessive alcohol intake and secondary osteoporosis (rheumatoid arthritis). The most important WHO-validated risk factors are age and prior fragility fracture. For any T-score value, fracture probability increases as age increases.1 Fracture Risk Assessment Tool (FRAX®),16
The WHO developed the a web-based fracture risk
algorithm that calculates the 10-year probability of a hip fracture and the 10-year probability of any major osteoporotic fracture. FRAX can be used in women and men 40–90 years of age who have not been treated for osteoporosis. A number of clinical risk factors are entered, along with the name of the DXA manufacturer and the femoral neck BMD (g/cm2) or T-score. In 2008, the National Osteoporosis Foundation (NOF) updated recommendations to assist in clinical decision-making for the treatment of osteoporosis.17
The
decision to initiate treatment should include clinical assessments, BMD, diagnostic work-ups, risk of fractures and clinical judgement. The NOF recommends that treatment be considered in post-menopausal women and men aged 50 and older with the following:
• •
• Hip or vertebral (clinical or morphometric) fracture.
Femoral neck or spine T-score is -2.5 or lower after evaluation to exclude secondary causes.
Low bone mass (femoral neck or spine T-score between -1.0 and -2.5) and the 10-year probability of hip fracture is over 3% or if there is a 10-year probability of any major osteoporosis-related fracture of over 20% based on the US-adapted FRAX.
Fracture Risk Assessment Tool Advantages and Limitations Fracture Risk Assessment Tool Advantages The FRAX analysis has many advantages, particularly the ability to assess fracture risk in patients with osteopenia, who constitute the majority of patients seen by clinicians and have the most fractures.18,19
Condition Description Normal
BMD value within 1 SD of the young adult reference mean (T>-1.0)
Osteopaenia BMD value of >1 SD below the young adult mean but <2.5 SD below this value (-1.0 > T>-2.5)
Osteoporosis BMD value of ≥2.5 SD below the adult mean value (T<-2.5) Established BMD value of ≥2.5 SD below the adult mean value osteoporosis (T<-2.5) in the presence of one or more fragility fractures
BMD = bone mineral density; SD = standard deviation.
Figure 1: World Health Organization Criteria for Defining Bone Density
hypercholesterolaemia; the FRAX algorithm can similarly guide decision-making for patients with osteopaenia or osteoporosis.
Fracture Risk Assessment Tool Limitations As with any tool, the FRAX analysis has limitations. The algorithm was developed from epidemiological data on post-menopausal women and men over 50 years of age and cannot be applied to pre-menopausal women or younger men. Fracture risk in pre-menopausal patients or men 50 years of age and younger with low bone mass is not known and may be low because they have not experienced the microarchitectural deterioration that occurs with menopause and the ageing process.20
Fracture risk cannot be
calculated in patients who are receiving treatment for osteoporosis, particularly bisphosphonates, because pharmacological therapy reduces fracture risk even when there is no change in BMD.21
Current
FRAX calculations use BMD or T-score of the femoral neck only because the clinical databases of BMD and fracture risk, on which FRAX is based, do not include other sites. (Fracture data are not adequate to use BMD of the spine.) However, the NOF has stated that the T-score of the total hip can be substituted.17
In addition, risk
factors (except for age and body mass index) are listed as dichotomous variables, but many factors have a gradient of risk. Although in the FRAX algorithm patients with three vertebral fractures have the same calculated risk as patients with a wrist fracture, they clearly have different risks of future fracture. Similarly, a patient who is receiving 60mg/day of prednisone does not have the same risk as a patient who received 5mg/day of prednisone for three months two years ago. In accordance with these limitations, while FRAX accounts for tobacco and alcohol use, which can increase the risk of osteoporosis, it does not ask how long or how much a patient has been smoking or drinking. Also FRAX does not include all risk factors (vitamin D deficiency, physical activity, the use of antiepileptic drugs and antidepressants that can erode bone, or falls risk). FRAX should be used as a mean to guide treatment decisions, but it is not a substitute for clinical judgement.
Accounting for Falls
Knowing the actual fracture risk in these patients helps physicians make clinical decisions. A 10-year fracture risk is easier for patients and their physicians to understand than a T-score and can be useful in risk-benefit analyses. Use of the FRAX algorithm may increase awareness and prevention efforts for men and persons in ethnic groups. The Framingham data on diabetes, coronary artery disease and hypertension have guided therapy for
EUROPEAN MUSCULOSKELETAL REVIEW
A fracture occurs when the force applied to the bone exceeds the strength of the bone. The vast majority of hip fractures, most other non-vertebral fractures and some vertebral fractures occur as a result of a fall. Falls have many different causes and older people may have several predisposing risk factors. Assessing falls risk can help to predict and even prevent falls. Identifying the underlying risk factor(s) the patient might have would also be of help to monitor this group of patients and assess their response to therapy. An example of how falls are commonly missed in the standard practice is the guidelines published by the European Society of Cardiology on the management
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