The WHO Fracture Risk Assessment Tool (FRAX), a simple tool recommended by the World Health Organization for fracture risk prediction, can be used to calculate the 10-year probability of hip fracture and any significant osteoporotic fracture occurrence.
1. Application method of FRAX
The calculation parameters of the tool include femoral neck bone mineral density and clinical risk factors. In the absence of femoral neck BMD can be replaced by total hip BMD, however, in this calculation method, the use of BMD at non-hip sites is not recommended. FRAX also provides calculations using only body mass index (BMI) and clinical risk factors for assessment when bone densitometry conditions are not available.
The common risk factors for fracture specified in FRAX are.
–Age: fracture risk increases with age
–Sex
–Low bone mineral density
–Low body mass index: ≤19 kg/m2
–previous history of fragility fractures, especially hip, distal ulnar radius and vertebral fractures
–Parental hip fracture
–Treatment with glucocorticoids: any dose, oral for 3 months or longer
–smoking
–An excessive consumption of alcohol
–Combination of other diseases causing secondary osteoporosis
–Rheumatoid arthritis
Since there is a lack of systematic pharmacoeconomic studies in China, there is no Chinese treatment threshold based on FRAX results. Clinically, we can refer to information from other countries, for example, the US guidelines mention that patients at high risk of osteoporotic fracture are considered when the FRAX tool calculates the probability of hip fracture ≥ 3% or the probability of any significant osteoporotic fracture ≥ 20%, while some European countries have a treatment threshold of hip fracture probability ≥ 5%. We can use our discretion in the application according to the individual situation.
2.Problems and limitations in the application of FRAX
(1) Application population
Not applicable population: clinically diagnosed osteoporosis, i.e. bone mineral density (T value) below -2.5, or fragility fracture has occurred, treatment should have been started promptly and FRAX assessment is not necessary.
Applicable population: People who have not had a fracture and have low bone mass (T value > -2.5), due to clinical difficulties in making treatment decisions, apply the FRAX tool, which can easily and quickly calculate the absolute risk of fracture for each individual and provide a basis for developing treatment strategies. The applicable population is 40 to 90 years old for men and women, and individuals <40 and >90 years old can be calculated as 40 or 90 years old, respectively.
(2) Issues of regional and ethnic differences
The determination of fracture-related risk factors in FRAX is based on primary data and large-sample meta-analyses from several independent, large-sample prospective population studies from around the world, including North America, Europe, Asia, and Australia, and therefore there is commonality. However, epidemiological information on fracture incidence and population mortality in the corresponding national populations is also required in the FRAX calculation model. Due to the lack of epidemiological data on fracture incidence in China, the FRAX tool in the Chinese population can only borrow epidemiological data from localized areas of the Chinese population and may have small deviations in general application, but such deviations will not be significant. The World Health Organization even suggests that those countries that do not yet have their own data can use the FRAX calculation tool that is closest to their own country, which is also a good reference value.
(3) Other factors related to fracture
In addition to the fracture risk factors addressed in the FRAX, there are a number of other factors that are also closely related to fracture. For example, most fractures in older adults occur after a fall, so falls are an important risk factor for the occurrence of fractures, but they are not included in the FRAX calculations. There are two reasons for this: one, the data from the cohort studies used to develop this tool are inconsistent in their reporting of falls in a form that is difficult to standardize; and two, there is no clear evidence that pharmacologic interventions reduce fracture risk in patients who have fallen. In practice, however, avoiding falls does appear to be an effective measure for fracture prevention.
The FRAX, a simple tool for fracture risk prediction, is available at the following URL.
Risk Factors
For clinical risk factors, please answer yes or no. If you do not fill in the form, it will be considered as no. See the Risk Factor Comments (clickable) for details.
The risk factors are as follows
Age The measurement model ranges from 40 to 90 years of age. If you enter an age below 40, the program will calculate the probability at age 40. If the age entered is higher than 90 years, the probability will be calculated at 90 years.
Gender Male or female. Please fill in appropriately.
Weight Please enter your weight in kilograms (kg).
Height Please enter the height in centimeters (cm).
History of previous fractures Previous fractures indicate precisely those fractures that occurred naturally in adulthood, or those that occurred as a result of trauma and should not have occurred in an individual with healthy bones. Please fill in yes or no (see risk factor notes for details).
Parental hip fracture This question asks whether the patient’s parents have a history of hip fracture. Please fill in yes or no.
Current smoking behavior Enter yes or no based on whether the patient currently smokes (see risk factor comments for details).
Adrenocorticosteroid use Enter “yes” if the patient is currently taking oral adrenocorticosteroids or has taken oral adrenocorticosteroids for more than three months and has a daily dose of 5 mg or more of ponisolone (or equivalent dose of other adrenocorticosteroids) (see Risk Factor Comments for details).
Rheumatoid arthritis Enter “Yes” if the patient has been diagnosed with rheumatoid arthritis. Otherwise, enter “No” (see Risk Factor Notes for details).
Secondary osteoporosis Enter “Yes” if the patient has a disease that is strongly associated with osteoporosis. These include type I diabetes (insulin-dependent), adult osteogenesis imperfecta, untreated chronic hyperthyroidism, hypogonadism or premature menopause (<45 years of age), chronic malnutrition or malabsorption, and chronic liver disease.
3 or more units of alcohol per day Enter “Yes” if the patient consumes 3 or more units of alcohol per day. The amount of alcohol units varies from 8 to 10 grams, depending on the quantitative standards of each country. This is equivalent to one standard beer (285 ml), one measured spirit (30 ml), one medium glass of wine (120 ml), or one measured aperitif (60 ml) (see Risk Factor Notes for details).
Bone mineral density (BMD) (BMD) Please select the model of dual-energy x-ray absorptiometry (DXA) used and enter the actual femoral neck BMD (in g/cm2). If the patient did not receive any BMD testing, leave this field blank (see Risk Factor Notes for details) (provided by the Oregon Osteoporosis Research Center).
Risk Factor Comments
History of previous fractures
Previous vertebral fractures should be specified. A previous fracture is counted as long as there is an occult fracture (morphometrically determined vertebral fracture) diagnosed by radiographic imaging. If the patient has a clinically diagnosed overt fracture, this can be counted as a very large risk factor. Therefore, the probability of fracture is higher than that calculated routinely. If there is a history of multiple previous fractures, the probability of fracture will also be higher than that calculated routinely.
Smoking, alcohol consumption, and adrenocorticotropic hormone intake
These risk factors are related to their intake dose. For example, the higher the intake, the higher the risk. In this model, the issue of intake dose is not taken into account, and the procedure is measured assuming only an average dose. Patients with low or high intakes need to be diagnosed based on clinical experience.
Rheumatoid arthritis (RA)
Rheumatoid arthritis RA is a risk factor for fracture. However, osteoarthritis has a lower risk of fracture. A patient’s self-administered “arthritis” will not be considered unless there is clinical or experimental evidence to support the diagnosis of arthritis.
Bone mineral density (BMD)
The BMD provided must be the bone mineral density of the femoral neck as provided by the DXA (Dual Energy Absorptiometry) instrument. The T-index obtained is based on the NHANES (National Health and Nutrition Examination Survey) reference values for women aged 20-29 years. The same absolute values were taken for males. Although this model was constructed based on the BMD values of the femoral neck, the overall hip BMD can also be applied to female patients to predict the probability of fracture.