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| FRAX | |
|---|---|
| Name | FRAX |
| Caption | Fracture risk assessment |
| Purpose | Fracture risk prediction |
| Developer | World Health Organization Collaborating Centre for Metabolic Bone Diseases at the University of Sheffield |
| Introduced | 2008 |
FRAX FRAX is a clinical tool designed to estimate 10-year probability of hip fracture and major osteoporotic fracture by integrating clinical risk factors with or without bone mineral density. It was developed to aid decision-making in management of osteoporosis and to harmonize thresholds used by agencies and professional societies across disparate health systems. The algorithm underpins guidelines and reimbursement policies in many countries and interfaces with risk stratification used by endocrinology, geriatrics, and primary care specialists.
Development began at the University of Sheffield under the auspices of the World Health Organization Collaborating Centre for Metabolic Bone Diseases, led by investigators including clinicians and epidemiologists connected to cohort studies such as the European Prospective Osteoporosis Study and the Study of Osteoporotic Fractures. Early modelling used population-based data from cohorts like MrOS (Osteoporotic Fractures in Men Study), the Nurses' Health Study, and national registries from Sweden, Denmark, and Finland. The initial public release in 2008 followed peer-reviewed methodological papers and consultation with organizations such as the International Osteoporosis Foundation and national agencies like the National Osteoporosis Foundation (US). Subsequent updates incorporated calibration to country-specific fracture and mortality rates, informed by surveillance from institutions such as Public Health England and the Centers for Disease Control and Prevention.
FRAX calculates absolute fracture probabilities by combining baseline hazard functions for hip fracture and major osteoporotic fracture with relative risks associated with clinical predictors. Input variables include age, sex, body mass index, history of prior fragility fracture, parental history of hip fracture, current smoking, long-term glucocorticoid use, rheumatoid arthritis, secondary causes of osteoporosis, alcohol intake, and optional femoral neck bone mineral density expressed as T-score from dual-energy X-ray absorptiometry machines certified by manufacturers and regulated in many countries by agencies such as the US Food and Drug Administration. Country-specific models use national mortality and fracture incidence data from registries like the Swedish Hip Fracture Register and the National Hip Fracture Database (UK). The algorithm combines these inputs using proportional hazard models and outputs 10-year probabilities for hip fracture and major osteoporotic fracture.
FRAX is incorporated into recommendations by professional bodies including the National Institute for Health and Care Excellence, the Endocrine Society, the American Association of Clinical Endocrinology, the International Osteoporosis Foundation, and national societies such as the Japanese Osteoporosis Society. It informs thresholds for treatment initiation, screening strategies, and reimbursement criteria used by payers like Medicare and national health services. Clinicians in primary care, endocrinology, rheumatology, geriatrics, and orthopedics use FRAX alongside clinical judgment, imaging, and laboratory assessment to guide pharmacologic interventions such as bisphosphonates, denosumab, selective estrogen receptor modulators, and anabolic agents recommended by agencies like the European Medicines Agency.
Validation studies have compared FRAX predictions with observed fracture incidence across cohorts including MrOS, Study of Osteoporotic Fractures, and population registries from Canada, Australia, Japan, and nations in Europe. External validation papers in journals with cohorts from the UK Biobank, the Framingham Heart Study, and national health databases showed variable calibration: good discrimination for hip fracture but more modest discrimination for major osteoporotic fractures. Meta-analyses led by groups affiliated with the Cochrane Collaboration and academic centers such as Johns Hopkins University evaluated sensitivity, specificity, and net reclassification improvement compared with simpler criteria like age thresholds or densitometry alone.
Critiques from researchers at institutions including Harvard Medical School and the Karolinska Institute emphasize that FRAX omits factors such as fall risk, dose-response for glucocorticoids, biochemical markers of bone turnover, and trabecular bone score unless incorporated separately. Concerns raised by policymakers in Australia and patient advocates in Canada focus on miscalibration in populations with atypical fracture patterns, ethnic heterogeneity not captured by country models, and lack of integration with secondary causes documented in specialist clinics. Methodologists have noted that prioritizing 10-year risk may underrepresent lifetime fracture risk in younger patients and that reliance on T-scores from variable DXA machines introduces measurement heterogeneity.
Country-specific FRAX models exist for over 60 jurisdictions calibrated to local fracture incidence and mortality, developed using data from national registries such as the Norwegian Hip Fracture Register, the Icelandic Osteoporosis Registry, and state registries in Spain. Modifications include incorporation of trabecular bone score by researchers linked to the University of Geneva and proposals to adjust glucocorticoid dose-response from teams at Mayo Clinic. Commercial electronic health record vendors and regional health systems, including those in Scotland and New Zealand, have integrated FRAX into clinical decision support with localized thresholds recommended by national guideline bodies like NICE.
FRAX has standardized assessment of fracture risk across specialties, influencing prescribing patterns for anti-osteoporotic therapies and prioritization of DXA scanning in limited-resource settings. Population health analyses by agencies such as the World Health Organization and national ministries of health have used FRAX-based modelling to estimate burden of disease, project costs, and design screening programs. Its use in guideline algorithms by organizations like the International Osteoporosis Foundation has shaped public health initiatives to reduce hip fracture incidence through fracture liaison services and secondary prevention programs in hospitals and community settings.
Category:Medical assessment tools