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Date of release: 22 December, 2008

FRAX: A fracture risk assessment tool


The 10-year probability of fracture in an individual can be calculated using the FRAX® fracture risk assessment tool. FRAX is available online [1] or as a paper model. The calculation of fracture risk, as well as utilization in management algorithms, is country-specific.


In a recent article [2], Kanis and colleagues explain that FRAX was developed using clinical risk factors, with and without bone mineral density, as identified in previous meta-analyses. Risk factors comprised age, sex, body mass index, a prior history of fracture, parental history of hip fracture, use of oral glucocorticoids, rheumatoid arthritis and other secondary causes of osteoporosis, current smoking and alcohol intake three or more units daily. The 10-year probability of fracture is expressed as a percentage for any major osteoporotic fracture or hip fracture. In a second publication [3], Kanis and colleagues used FRAX and a prior study on the cost-effectiveness of generic alendronate to determine a fracture intervention threshold. Treatment was cost-effective at all ages if the 10-year probability of a major osteoporotic fracture exceeded 7%.

Comment

Fracture risk should only be calculated using a combination of all available risk factors. FRAX is a huge step forward in presenting the clinician with a user-friendly integrated model based on large epidemiological data. However, FRAX has limitations. At present, the country-specific calculation is only available for some countries. Furthermore, FRAX does not tell us when to treat. A case-finding calculation will have to be done for every country, based on the local availability and cost of suitable drugs. The fracture intervention threshold, as calculated in the second study, only considers the use of generic alendronate. Is this appropriate?
At present, it is accepted in most countries that a patient with a T-score equal to or less than -2.5 at L1–L4 or the femur neck or total femur or a previous fragility fracture should be treated. This is unlikely to change. FRAX is thus aimed at identifying the osteopenic patient (bone mineral density (BMD) T-score < -1.0 and > -2.5) at sufficient risk of fracture to warrant treatment. In the case of the patient with a BMD T-score < 2.5 or a previous fragility fracture, we have several drugs proven to prevent fractures. The evidence was established in large, randomized controlled trials (RCTs). In the case of the osteopenic patient, however, only strontium ranelate and estrogen/progestin hormone therapy (HT) have proven efficacy in RCTs. Small post hoc analyses support the use of risedronate and raloxifene in the prevention of fracture in the osteopenic patient. In the fracture intervention trial (FIT2), original alendronate did not reduce fracture risk in the osteopenic patient without a fracture. Alendronate would thus not be my choice of therapy in the osteopenic patient at risk of fracture. In the patient aged 50–60 years, HT would be a better choice and strontium ranelate in the patient after age 60 years. My concern is that FRAX and related intervention thresholds will be abused by regulators and third-party insurers to enforce rigid algorithms with limited flexibility for good clinical judgement. We should be very careful not to use FRAX beyond its limitations.

Comentario

Tobie J. de Villiers
Consultant Gynaecologist, Panorama MediClinic, Cape Town South Africa

  1. Kanis JA, Johnell O, Oden A, Johansson H, McCloskey E. FRAX and the assessment of fracture probability in men and women from the UK. Osteoporos Int 2008;19:385-97. Published April, 2008.
    http://www.ncbi.nlm.nih.gov/pubmed/18292978

  2. Kanis JA, McCloskey EV, Johansson H, et al. Case finding for the management of osteoporosis with FRAX assessment and intervention thresholds for the UK. Osteoporos Int 2008;19:1395-408. Published October, 2008.
    http://www.ncbi.nlm.nih.gov/pubmed/18751937