Osteoporosis Risk (FRAX) Calculator

Baseline hip fracture risk in this calculator rises exponentially with age -- from roughly 0.2% at 45 to 12% at 85 for a woman with no other risk factors -- while individual risk factors like smoking or rheumatoid arthritis each apply a fixed hazard-ratio multiplier (1.36x and 1.35x respectively) on top of whatever that age-based baseline turns out to be. Because the baseline itself moves by roughly 60-fold across the calculator's full age range, age dominates the estimate even though clinical risk factors meaningfully shift the number at any given age. Femoral neck T-score is the exception among the inputs: it's continuous rather than a fixed multiplier, and across its own full -5 to 2 range it produces a bigger swing in hip fracture probability than age does across its 40-90 range, so this comparison is specifically about age versus the binary clinical risk factors, not T-score.

A prior fragility fracture applies a 1.85x hazard-ratio multiplier to the baseline hip fracture probability, the single largest individual risk-factor multiplier in this calculator -- larger than glucocorticoid use (1.7x), heavy alcohol use (1.65x), parental hip fracture (1.49x), smoking (1.36x), rheumatoid arthritis (1.35x), or secondary osteoporosis (1.25x). That ranking reflects the FRAX validation literature's finding that a fragility fracture as an adult is one of the strongest available predictors of a future fracture.

The calculator flags treatment as recommended once the 10-year hip fracture probability reaches 3%, the major osteoporotic fracture probability reaches 20%, or the femoral neck T-score is -2.5 or lower -- any one of the three is sufficient on its own. These are the National Osteoporosis Foundation's published intervention thresholds for the US, not universal cut points; several other countries use different FRAX-based thresholds calibrated to their own population fracture rates and treatment cost-effectiveness data.

No -- treat this as a screening approximation, not a replacement. It uses the same risk factors as the official WHO FRAX tool but combines them with published hazard ratios in a simplified multiplicative model rather than FRAX's own country-calibrated statistical algorithm, which accounts for local baseline fracture rates and competing mortality risk that this calculator does not. If this estimate lands anywhere near the treatment thresholds, the next step is the official FRAX tool or a DEXA scan and a clinician's evaluation, not treatment decisions based on this number alone.