Bone health topics
FRAX: Fracture Risk Assessment Tool
FRAX estimates a person’s 10-year probability of hip fracture and major osteoporotic fracture. It is useful because it puts bone density, age, prior fracture, medications, family history, and other risk factors into one estimate. It is not a diagnosis, and it is not the whole clinical picture.
The short version
FRAX is an online fracture-risk calculator. The official FRAX model combines clinical risk factors with, when available, femoral neck bone mineral density to estimate fracture probability.1
The result is not a pass-fail score. A low number can still matter if someone has had a recent fracture, multiple fractures, frequent falls, high-dose steroid exposure, frailty, or another risk that is not fully captured by the calculator.4,7
What FRAX estimates
The official FRAX output gives two probabilities: hip fracture and major osteoporotic fracture. Major osteoporotic fracture includes clinical spine, forearm, hip, or shoulder fracture.1
A 3% hip fracture probability means that, in a group of 100 people with a similar risk profile, about 3 would be expected to have a hip fracture over 10 years. A 20% major osteoporotic fracture probability means about 20 of 100 similar people would be expected to have a major osteoporotic fracture over 10 years. These are population-based estimates, not a personal prediction of exactly what will happen.
A 2020 review reported that FRAX was released in 2008, had 71 models for 66 countries, covered more than 80% of the world population, received about 3 million website visits annually, and had been incorporated into more than 80 guidelines worldwide.2
What goes into the calculation
The official FRAX calculator asks yes-or-no questions for most risk factors. If a risk-factor field is left blank, the tool assumes no. Femoral neck BMD can be added if available, but FRAX can also be calculated without BMD.1,6
| Input | What it is trying to capture | Clinical note |
|---|---|---|
| Age, sex, height, and weight | Baseline fracture probability and body size. | Age is one of the strongest drivers of absolute fracture probability. |
| Previous fracture | Adult fragility fracture history. | Recent, multiple, hip, and clinical vertebral fractures may raise risk more than the basic checkbox shows.1 |
| Parent hip fracture | Family history of hip fracture in a mother or father. | This is more specific than a general family history of osteoporosis. |
| Current smoking | Ongoing tobacco exposure. | Smoking effects can be dose-related; the FRAX checkbox uses an average exposure assumption.1 |
| Glucocorticoids | Oral steroid exposure, usually prednisolone 5 mg daily or more for more than 3 months, or equivalent. | Higher-dose exposure may require clinical adjustment beyond the basic yes-or-no entry.1 |
| Rheumatoid arthritis | A confirmed rheumatoid arthritis diagnosis. | FRAX specifically means rheumatoid arthritis, not just any joint pain or osteoarthritis.1 |
| Secondary osteoporosis | Selected conditions strongly associated with osteoporosis. | Examples listed by the calculator include type 1 diabetes, untreated long-standing hyperthyroidism, hypogonadism or premature menopause before age 45, chronic malnutrition or malabsorption, chronic renal failure, and chronic liver disease.1 |
| Alcohol 3 or more units per day | Higher alcohol exposure. | Like smoking and steroids, dose matters clinically. |
| Femoral neck BMD or T-score | Bone density at the femoral neck. | FRAX uses femoral neck BMD, not lumbar spine BMD, for the BMD entry.1 |
How the 3% and 20% thresholds are used
In many U.S. osteoporosis conversations, medication is considered when FRAX estimates a 10-year hip fracture probability of 3% or higher, or a 10-year major osteoporotic fracture probability of 20% or higher, especially in someone with low bone mass rather than osteoporosis-range BMD. These thresholds are decision aids, not automatic treatment rules.3,5
A systematic review and meta-analysis of FRAX using the U.S. 20% major osteoporotic fracture and 3% hip fracture thresholds found that FRAX performed better at identifying people who would not fracture over 10 years than at identifying every person who would fracture. In plain English: a low-risk FRAX estimate can be reassuring, but it does not catch every future fracture.3
That is why a FRAX number should be paired with the actual story: prior fracture, spine imaging, fall frequency, medications, cancer therapy, steroid dose, frailty, diabetes, kidney disease, and whether the DXA scan itself was technically reliable.
When FRAX may underestimate risk
- Frequent falls: a position statement concluded that fracture probability may be underestimated in people with frequent falls and that falls risk should be included in decision-making.4
- Recent or multiple fractures: the official calculator notes that recent fracture, multiple prior fractures, prior hip fracture, and clinical vertebral fracture may make risk higher than the baseline FRAX estimate.1
- Higher-dose exposures: smoking, alcohol, and glucocorticoids can have dose-related effects, while the standard FRAX entries use yes-or-no assumptions.1,7
- Spine-hip mismatch: FRAX uses femoral neck BMD when BMD is entered. A much lower lumbar spine result, vertebral fracture, or artifact on the scan may need separate interpretation.
What to ask at a visit
- Was FRAX calculated with femoral neck BMD, without BMD, or with the wrong BMD site?
- What are the 10-year hip fracture and major osteoporotic fracture probabilities?
- Do the 3% hip or 20% major osteoporotic fracture thresholds apply to this situation?
- Does a prior fracture, recent fracture, vertebral compression fracture, or frequent falls change the risk discussion?
- Do steroid dose, smoking, alcohol, diabetes, kidney disease, cancer therapy, or other conditions make the FRAX number an underestimate?
- Would a fall-prevention plan, strength and balance work, nutrition review, lab evaluation, or osteoporosis medication discussion change the next step?
How to use this page
Use FRAX to organize the risk conversation, not to replace it. A clinician can combine the FRAX estimate with DXA quality, fracture history, fall risk, medical conditions, medications, and patient priorities. That fuller picture is what matters for preventing fractures and protecting mobility over time.
References
- FRAXplus. FRAX calculator and risk-factor notes. Osteoporosis Research Ltd, UK. https://www.fraxplus.org/calculation-tool
- Kanis JA, Harvey NC, Johansson H, Liu E, Vandenput L, Lorentzon M, Leslie WD, McCloskey EV. A decade of FRAX: how has it changed the management of osteoporosis? Aging Clin Exp Res. 2020;32(2):187-196. PMID: 32043227. doi:10.1007/s40520-019-01432-y.
- Jiang X, Gruner M, Tremollieres F, Pluskiewicz W, Sornay-Rendu E, Adamczyk P, Schnatz PF. Diagnostic accuracy of FRAX in predicting the 10-year risk of osteoporotic fractures using the USA treatment thresholds: a systematic review and meta-analysis. Bone. 2017;99:20-25. PMID: 28274799. doi:10.1016/j.bone.2017.02.008.
- Masud T, Binkley N, Boonen S, Hannan MT. Official Positions for FRAX clinical regarding falls and frailty: can falls and frailty be used in FRAX? J Clin Densitom. 2011;14(3):194-204. PMID: 21810525. doi:10.1016/j.jocd.2011.05.010.
- The Advisory Board of the National Osteoporosis Guideline Group, Kanis JA, Harvey NC, Cooper C, Johansson H, Oden A, McCloskey EV. A systematic review of intervention thresholds based on FRAX. Arch Osteoporos. 2016;11(1):25. PMID: 27465509. doi:10.1007/s11657-016-0278-z.
- Kanis JA, McCloskey E, Johansson H, Oden A, Leslie WD. FRAX with and without bone mineral density. Calcif Tissue Int. 2012;90(1):1-13. PMID: 22057815. doi:10.1007/s00223-011-9544-7.
- Task Force of the FRAX Initiative, Kanis JA, Hans D, Cooper C, et al. Interpretation and use of FRAX in clinical practice. Osteoporos Int. 2011;22(9):2395-2411. PMID: 21779818. doi:10.1007/s00198-011-1713-z.
- Adami G, Biffi A, Porcu G, et al. A systematic review on the performance of fracture risk assessment tools: FRAX, DeFRA, FRA-HS. J Endocrinol Invest. 2023;46(11):2289-2299. PMID: 37031450. doi:10.1007/s40618-023-02082-8.
- Schini M, Johansson H, Harvey NC, Lorentzon M, Kanis JA, McCloskey EV. An overview of the use of the fracture risk assessment tool (FRAX) in osteoporosis. J Endocrinol Invest. 2024;47(3):501-511. PMID: 37874461. doi:10.1007/s40618-023-02219-9.
Educational Use Only
This website is educational. It is not a medical practice, telemedicine service, or a substitute for care from your own clinician.