Assessment of fracture risk key in osteoporosis
How should osteoporosis be diagnosed?
How will the FRAX calculator aid assessment?
What treatment options are recommended?
Osteoporotic fractures are a major health problem in older people, affecting one in two women and one in five men over 50. These fractures are associated with significant morbidity and increased mortality, and cost the health services an estimated £1.8 billion annually.1
The diagnosis of osteoporosis has traditionally been based on the measurement of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) at the lumbar vertebrae and proximal femur.
A T-score (the number of SDs below normal peak bone mass) of ?-2.5 indicates osteoporosis.2
DXA measurements can also be performed at the wrist. A low T-score can be regarded as a risk factor but should not be used to diagnose osteoporosis.
The risk of fracture increases progressively with decreasing BMD. However, the use of BMD alone to predict fracture risk has a high specificity but low sensitivity, and the majority of fractures occur in patients with a BMD T-score higher than -2.5.
Recently, it has been shown that prediction of fracture risk can be improved by the use of clinical risk factors independent of BMD, see table 1, attached.3 These risk factors, alone or in combination with BMD measurement, form the basis of the WHO-supported FRAX tool for predicting fracture risk. This is available free online at www.shef.ac.uk/frax and can be used to assess the 10-year probability of a patient developing a major osteoporotic fracture (wrist, spine, hip and humerus) or hip fracture.
Population-based screening for osteoporosis is not recommended at present. However, a case-finding approach is used, in which postmenopausal women and men over 50 are identified on the basis of clinical risk factors, see table 1.
The 10-year fracture risk is estimated using FRAX and a decision can then be made about whether treatment is indicated or whether a BMD measurement should be taken.
The recent guideline from the National Osteoporosis Guideline Group provides recommendations on the assessment of fracture risk, see figure 1, attached. The guideline is linked to the FRAX tool and includes graphs to show intervention thresholds based on patient age and 10-year fracture risk (with or without assessment of BMD).4
A number of drug treatments have been approved for the prevention of fractures in postmenopausal women, see table 2, attached.5 All have been shown to reduce vertebral fracture risk when given with calcium and vitamin D supplements, and some have been shown to reduce non-vertebral fractures, such as alendronic acid, risedronate, zoledronate and strontium ranelate, in some cases specifically at the hip.
Alendronic acid, risedronate and teriparatide are also approved for men at high risk of fracture, and alendronic acid, risedronate, etidronate and teriparatide are approved for the treatment of glucocorticoid-induced osteoporosis.
Alendronic acid is the first-line treatment in the majority of cases because of its broad spectrum of efficacy across fracture sites. The once weekly formulation is preferred by the vast majority of patients.
If the patient is unable to take or tolerate alendronic acid, other bisphosphonates, strontium ranelate or raloxifene can be used.
Parathyroid hormone peptide therapy should be restricted to patients with severe vertebral osteoporosis who are unable to take any of the other treatments and requires referral to a specialist.
Falls risk assessment and prevention is an important aspect of the management of osteoporosis.6 Other measures include maintenance of mobility, advice about smoking cessation and alcohol intake, and correction of vitamin D deficiency.
Nutritional advice is also important and adequate calcium and protein intake should be ensured. Calcium and vitamin D supplements should be prescribed unless there is clear evidence of a normal vitamin D level and adequate dietary calcium intake. The recommended daily doses of calcium and vitamin D are 1-1.2g and 800IU respectively.
The optimum duration of bone protective treatment is unknown. For antiresorptives, treatment is often for 5-10 years, after which time the need for continuation of therapy is reassessed.
The use of biochemical markers of bone turnover and/or BMD in the routine monitoring of treatment is controversial.
Patient education before starting therapy is likely to be beneficial. There is also some evidence that adherence to treatment can be improved by a doctor or osteoporosis nurse discussing therapy with the patient a few months after starting treatment.7
NICE has recently produced new guidance on the primary and secondary prevention of osteoporotic fractures.8,9 This guidance is restricted to postmenopausal women with osteoporosis and excludes men, patients taking oral glucocorticoids, and does not include newer interventions such as ibandronic acid and zoledronic acid.
FRAX is not incorporated in the NICE guidance and intervention thresholds are based on age, T-scores and the presence of a fracture.
In contrast, the NOGG guideline covers the primary and secondary prevention of osteoporotic fractures in postmenopausal women and in men over 50 years, and includes those taking oral glucocorticoids.
Professor Juliet Compston
MD, FRCPath, FRCP, FMedSci
Professor of Bone Medicine, University of Cambridge School of Clinical Medicine and Addenbrooke's NHS Trust, Cambridge
Key points Table 1: Clinical risk factors used for the assessment Table 2: Therapies for prevention of osteoporotic fractures Figure 1: Case finding strategy