Frax Calculator | FRAXplus®

Risk factors

For the clinical risk factors a yes or no response is asked for. If the field is left blank, then a "no" response is assumed. See also notes on risk factors

The risk factors used are the following:

The model accepts ages between 40 and 90 years. If ages below or above are entered, the program will compute probabilities at 40 and 90 years, respectively.

Male or female. Enter as appropriate.

This should be entered in kg or pounds (please select units)

This should be entered in cm or inches (please select units)

A previous fracture denotes more accurately a previous fracture in adult life occurring spontaneously, or a fracture arising from trauma which, in a healthy individual, would not have resulted in a fracture. Enter yes or no (see also notes on risk factors).

This enquires for a history of hip fracture in the patient's mother or father. Enter yes or no.

Enter yes or no depending on whether the patient currently smokes tobacco (see also notes on risk factors).

Enter yes if the patient is currently exposed to oral glucocorticoids or has been exposed to oral glucocorticoids for more than 3 months at a dose of prednisolone of 5mg daily or more (or equivalent doses of other glucocorticoids) (see also notes on risk factors).

Enter yes where the patient has a confirmed diagnosis of rheumatoid arthritis. Otherwise enter no (see also notes on risk factors).

Enter yes if the patient has a disorder strongly associated with osteoporosis. These include type I (insulin-dependent) diabetes, osteogenesis imperfecta in adults, untreated long-standing hyperthyroidism, hypogonadism or premature menopause (<45 years), chronic malnutrition or malabsorption, chronic renal failure (dialysis independent) and chronic liver disease.

Enter yes if the patient takes 3 or more units of alcohol daily. A unit of alcohol varies slightly in different countries from 8-10g of alcohol. This is equivalent to a standard glass of beer (285ml), a single measure of spirits (30ml), a medium-sized glass of wine (120ml), or 1 measure of an aperitif (60ml) (see also notes on risk factors).

In patients without a BMD test, the field should be left blank. If entering absolute BMD - Please select make of scanning equipment used and enter actual femoral neck BMD (in g/cm²). If entering T-score - Please select the T-score option and enter the T-score based on the NHANES III female reference data. See also notes on risk factors.

Notes on risk factors

Previous fracture

A special situation pertains to a prior history of vertebral fracture. A fracture detected as a radiographic observation alone (a morphometric vertebral fracture) counts as a previous fracture. A prior clinical vertebral fracture or a hip fracture is an especially strong risk factor, and the probability of fracture may therefore be underestimated. A fracture within the past 2 years is a particularly strong risk factor for subsequent fracture, and fracture probability is also likely to be underestimated with multiple prior fractures. Adjustments of FRAX^® probabilities for recency or number of prior fractures are available using FRAXplus^®.

Smoking, alcohol, glucocorticoids

These risk factors appear to have a dose-dependent effect, i.e. the higher the exposure, the greater the risk. Current FRAX^® computations assume average exposure and clinical judgment should be used for low or high exposures. FRAX^® probabilities can be adjusted using FRAXplus^® for exposure to higher-than-average doses of glucocorticoids.

Rheumatoid arthritis (RA)

RA is a risk factor for fracture. However, osteoarthritis is, if anything, protective. For this reason, reliance should not be placed on a patient's report of 'arthritis' unless there is clinical or laboratory evidence to support the diagnosis.

Bone mineral density (BMD)

The site and reference technology is DXA at the femoral neck. T-scores are based on the NHANES reference values for women age 20-29 years. The same absolute values are used in men.

Notes on adjustment factors

The risk of a recurrent fragility fracture is particularly high immediately following the fracture. FRAXplus^® provides adjustments to FRAX^®-based fracture probabilities accounting for the site of a recent fracture [Kanis 2020].

Reference: Kanis JA, Johansson H, Harvey NC, Gudnason V, Sigurdsson G, Siggeirsdottir K, Lorentzon M, Liu M, Vandenput L, McCloskey E (2020) Adjusting conventional FRAX estimates of fracture probability according to the recency of sentinel fractures. Osteoporosis International 31: 1817-1828.

Moderate doses of glucocorticoids (2.5–7.5 mg prednisolone daily or equivalent) are the assumed exposure in the FRAX^® calculation. For high doses (>7.5 mg daily), MOF probabilities are upward revised by about 15% and hip fracture probabilities by 20%. Simple adjustments can be made by hand and are available [Kanis et al 2011]. FRAXplus^® gives a more accurate adjustment based on empirical data.

Reference: Kanis JA, Johansson H, Oden A, McCloskey EV (2011)Guidance for the adjustment of FRAX according to the dose of glucocorticoids. Osteoporos Int 22(3): 809-16.

FRAX^® underestimates fracture risk in patients with type 2 diabetes. Several methods for adjusting fracture probabilities have been proposed [Leslie 2018]. The most simple is to enter ‘yes’ in the rheumatoid arthritis input to FRAX^®.
FRAXplus^® incorporates a further adjustment for the duration of Type 2 diabetes mellitus which also influences fracture risk.

Reference: Leslie WD, Johansson H, McCloskey EV, Harvey NC, Kanis JA, Hans D (2018) Comparison of methods for improving fracture risk assessment in diabetes: The Manitoba BMD Registry. J Bone Mineral Res 33: 1923-30.

Major discordances between lumbar spine (LS) and femoral neck (FN) BMD T-scores are relatively uncommon but may enhance the assessment of major osteoporotic fracture (MOF) risk where they exist. Generally, a much higher LS T-score than FN T-score will lower MOF, and vice versa. FRAXplus^® allows easy incorporation of this discordance where required.

Reference: Johansson H, Kanis JA, Oden A, Leslie WD et al. (2014). Impact of femoral neck and lumbar spine BMD discordances on FRAX probabilities in women: a meta-analysis of international cohorts. Calcif Tissue Int, 95(5), 428-435.

Number of prior fractures (NPF)

The Trabecular Bone Score (TBS) is derived from the texture of the DXA image at the lumbar spine and provides an index of bone microarchitecture. A low TBS is associated with an increased risk of fracture independent of FRAX^® and femoral neck BMD. FRAXplus^® provides access to a validated adjustment [McCloskey 2015, 2016]. TBS values calculated with TBS iNsight version 2.1 and above can be used to compute FRAX^® adjusted for TBS. (only available when BMD obtained from GE-Lunar or Hologic devices).

Reference McCloskey EV, Odén A, Harvey NC, et al (2016) A meta-analysis of Trabecular Bone Score in fracture risk prediction and its relationship to FRAX. J Bone Mineral Res 31: 940-8.

A history of falls is associated with increased hip and MOF fracture risk. FRAX^® currently assumes an average exposure to falls in the last year. Adjustments for a history of 0, 1, 2 and 3 or more falls in the previous year have been derived from an analysis within the Manitoba cohort and implemented within FRAXplus^®.

Reference: Kanis JA, Johansson H, Harvey NC, Lorentzon M, Liu E, Vandenput L, Morin S, Leslie WD, McCloskey EV (2023). Adjusting conventional FRAX estimates of fracture probability according to the number of prior falls in the preceding year. Osteoporos Int, 34(3), 479-487.

Longer than average hip axis length (HAL) is associated with an increase in hip fracture risk. Conversely, shorter than average length is associated with a lower risk. FRAXplus^® enables an adjustment of FRAX^® hip fracture probability for the measured HAL.

Primary hyperparathyroidism (PHPT)

Age

Sex

Weight

Height

Previous fracture

Parent fractured hip

Current smoking

Glucocorticoids

Rheumatoid arthritis

Secondary osteoporosis

Alcohol 3 or more units/day

Bone mineral density (BMD)

Recency of osteoporotic fracture

High exposure to oral glucocorticoids

Type 2 diabetes mellitus

Concurrent data on lumbar spine BMD

Number of prior fractures

Information on trabecular bone score (TBS)

Falls history

Hip axis length

Primary hyperparathyroidism