Frequently Asked Questions
- On what data is this model based?
- Why use a 10 year risk model?
- Are there other web-based fracture risk models?
- How does the current FORE model differ from the WHO FRAX™ model?
- Don't the types of fracture change with age?
- Why weren't other fractures included?
- Why aren't other clinical risk factors included?
- Won't the WHO FRAX™ model replace the FORE model?
- How should this model help in counseling patients and making decisions?
- Can the model be used for men or for different ethnicities?
- What if the patient is being treated for osteoporosis?
- What about falls and frailty?
- Why were these thresholds (low, moderate, high) chosen?
On what data is this model based?
This model uses several easily ascertained items plus bone mineral density (BMD) to
calculate 10-year absolute fracture risk. The model begins by assigning the average
fracture rate based on the patient's age. These population rates come from the World
Health Organization (WHO) FRAX™ model tables
(http://www.shef.ac.uk/FRAX) specifically for
the US. The model calculates differences between the patient and the reference population
in several clinical risk factors including bone mineral density (BMD). Each risk factor's
relative risk is used to modify the expected fracture rate. The risk factors and relative
risks have been derived from the WHO FRAX™ model1.
Why use a 10 year risk model?
Excellent risk-assessment models 2,3 exist for
other diseases and have been translated into computer software that calculates absolute
risk of event from multiple variables. These models include the one widely used to
predict 5- and 10-year risks for breast cancer 2 and
the National Cholesterol Education Program's model for predicting 10-year risk of
coronary heart disease.3 Both models have been
used in developing best practice guidelines, are widely recommended to guide therapeutic
intervention, and are well accepted by clinicians. Cost-effectiveness analyses 4 and
treatment recommendations based on these analyses 5 have now been published for
osteoporosis drugs.
Are there other web-based fracture risk models?
The WHO FRAX™ model essentially replaces all previous web-based models because it is so accurate and comprehensive.
How does the current FORE model differ from the WHO FRAX™ model?
The FORE model and FRAX™ model use the same input variables, the same base fracture rates, and the same relative
risks (multipliers). Both can be applied to men and 4 different ethnicities. Both output the 10-year risk of hip
and any one of 4 fractures (hip, wrist, humerus, clinical spine). One major difference is that the FORE model provides
a graphic display of risk, comparing it to the expected risk, and categorizing it as low, medium, or high. A second
difference is the FRAX™ model performs more adjustments for interactions between variables. Thus, users of these
models should get very similar but not identical results.
Don't the types of fracture change with age?
The FORE and FRAX™ models provide 10-year absolute fracture risk for a hip fracture and for any one of 4 fractures
(hip, spine, humerus, or wrist). The mix of fractures changes with age: at 45-49 years, hip fractures constitute only
7% but increase to 50% at 75 years.6 In contrast, the proportion of wrist fractures decreases with age, from
60% among the younger group to 26% among the older.
Why weren't other fractures included?
Both the FORE and FRAX™ models include four clinical osteoporotic fracture locations (i.e., spine,
wrist, humerus, and hip) for several reasons: low BMD is a demonstrated risk factor
for these fracture types;7 these fractures constitute
the majority of osteoporotic (fragility-type) fractures;7 accurate
rates of fracture incidence for the age range of interest were available from reliable
published data1 and these fractures are costly
to treat and can seriously alter quality of life.8
Why aren't other clinical risk factors included?
Both the FORE and FRAX™ models aim to keep the model data entry simple and in an easily understood format.
Both use risk factors whose individual contributions to fracture risk have been
estimated in large epidemiologic studies using multivariable models; the risk factors
are the same as those used in cost-effectiveness analyses.4
Won't the WHO FRAX™ model replace the FORE model?
The WHO model will become the standard in the field and will be incorporated into BMD reporting.
In the FORE model, we have tried, as much as possible, to use the rates and relative risks that
appear in the WHO model. The FORE model adds graphic display and categorization of risk—that
should be helpful in explaining risks and need for treatment to patients.
How should this model help in counseling
patients and making decisions?
Models could promote awareness of the need for treatment among overlooked women in
their 60s who have a number of risk factors but no clinically apparent osteoporosis
(i.e. T-score not <-2.5). Fracture models appear to have the greatest value
in solving the common clinical conundrum of osteopenia in healthy, early postmenopausal
women. Giving a patient her absolute risk and discussing risk reduction expected from
treatment in an easily understandable context enriches the quality and accuracy of
information both clinicians and patients use for making decisions.
Can the model be used for men? For different ethnicities?
Both FORE and FRAX™ models can be used for men and for 4 different ethnicities (Caucasian, Hispanic, Black, Asian).
Simply select gender and ethnicity in the input fields.
What if the patient is being treated for
osteoporosis?
This model is based on fracture rates in untreated women and does not account for
osteoporosis treatment effects. Best estimates are that bisphosphonate therapy results in a 35% reduction
in the risk of any of one of four fractures (spine, wrist, humerus, hip).4,5,9
What about falls and frailty?
This model does not capture the additional risks imposed by falling and frailty because
it is intended as a guide to drug therapy and current drugs do not modify these risk
factors.
Why were these thresholds (low, moderate,
high) chosen?
Cost-effectiveness analyses and treatment guidelines based on US costs and fracture rates
have recently been published.4,5 The thresholds cited are 3% or more for 10-year risk
of hip fracture and 20% or more for 10-year risk of any one of 4 fractures. The FORE model
shows rates above the 20% threshold as high risk, includes an intermediate zone (10-20%),
as well as a low risk zone (<10%). These same percentage cut points are used for cardiovascular
disease (National Cholesterol Education Program)3 and have been adopted by expert osteoporosis
groups.10 In counseling patients, we find that most individuals start to worry about risk
when it reaches "double digits" and 20% (1 in 5) is usually of great concern. Providing absolute
risks rather than relative ones allows patients to make better informed decisions about
therapy.11
References
- Kanis JA, Johnell O, Oden A, Johnsson H, McCloskey E. Frax and the assessment of fracture probability in men and women from the UK. Osteoporos Int DOI 10.1007/s00198-007-0543-5.
- Benichou J. A computer program for estimating individualized probabilities of breast cancer. Comput Biomed Res 1993; 26:373-82.
- Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. Executive Summary of the third report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). JAMA 2001; 285:2486-97.
- Tosteson ANA, Melton II LJ, Dawson-Hughes B, Baim S, Favus MJ, Khosla S, Lindsay RL. Cost-effective osteoporosis treatment thresholds: the United States perspective. Osteoporos Int DOI 10:1007/s00198-007-0550-6.
- Dawson-Hughes B, Tosteson ANA, Melton III LJ, Baim S, Favus ML, Khosla S, Lindsay RL. Implications of absolute fracture risk assessment for osteoporosis practice guidelines in the USA. Osteoporos Int DOI 10:1007/s00198-008-0559-5.
- Ettinger B, Hillier TA, Pressman AR, Che M, Hanley DA. Simple computer model for calculating 5-year osteoporotic fracture risk in postmenopausal women. J Women's Health 2005; 14:159-171.
- Seeley DG, Browner WS, Nevitt MC, Genant HK, Scott JC, Cummings SR. Which fractures are associated with low appendicular bone mass in elderly women? Study of Osteoporotic Fractures Research Group. Ann Intern Med 1991; 115:837-42.
- Ray NF, Chan JK, Thamer M, Melton LJ 3rd. Medical expenditures for the treatment of osteoporotic fractures in the United States in 1995: report from the National Osteoporosis Foundation. J Bone Miner Res 1997; 12:24-35.
- Kanis JA, Borgstrom F, Zethraeus N, Johnell O, Oden A, Jonsson B. Intervention thresholds for osteoporosis in the UK. Bone 2005; 36: 22-32.
- Siminoski K, Leslie WD, Frame H, et al. Recommendations for bone mineral density reporting in Canada. Can Assoc Radiol J 2005; 56:178-88.
- Hux JE, Naylor CD. Communicating the benefits of chronic preventive therapy: does the format of efficacy data determine patients' acceptance of treatment? Med Decis Making 1995; 15:152-7.