FRAX Score

FRAX is an algorithm that integrates the weight of clinical risk factors for fracture, with or without BMD, and computes the 10-year probability of hip fracture and of a major osteoporotic fracture (hip, clinical spine, proximal humerus, distal forearm). It was developed by Kanis and the WHO Collaborating Centre, Sheffield.

The eleven inputs: age (40–90), sex, weight, height, previous fragility fracture, parental hip fracture, current smoking, glucocorticoid use, rheumatoid arthritis, secondary osteoporosis, alcohol ≥3 units/day, and (optionally) femoral neck BMD.

Country-specific calibration: the tool is region-specific because fracture and death rates differ widely between populations — an Indian FRAX model exists and must be used for Indian patients.

Clinical use: FRAX output is compared with a country-specific intervention threshold. In Pathy's algorithm, treatment is offered when the FRAX probability for major osteoporotic (or hip) fracture reaches a risk equivalent to that associated with a prevalent fragility fracture — an age-dependent threshold. FRAX also identifies who needs a DXA when access is limited.

Modifiers that refine FRAX: BMD, trabecular bone score (TBS), glucocorticoid dose, fall history, type 2 diabetes and hip axis length.

Advantages: free, quick, usable without DXA, validated in large international cohorts, and it shifts practice from a pure BMD threshold to absolute risk — important because most fractures occur in people who are only osteopenic.

Limitations: does not capture falls, number or recency of fractures (it treats one fracture the same as five), dose of glucocorticoid, lumbar spine BMD, vitamin D status, or frailty; it is not validated on treatment and is capped at 90 years; it therefore underestimates imminent risk immediately after a fracture.