Revised Swedish FRAX models and the establishment of age-dependent intervention thresholds

Summary: We developed a revised FRAX® model for Sweden, derived from recent incidence data on fractures, mortality, and origin of birth, and defined age-dependent intervention thresholds.

Purpose: Since the development of the Swedish FRAX model in 2008, fracture incidence patterns have changed. The primary aim of this study was to develop a revised FRAX model, based on region of birth, and updated incidences for death and fracture for Sweden. A secondary aim was to define age-dependent intervention thresholds.

Methods: Based on national registries, all persons from the age of 40 years living in Sweden between 2005 and 2021 were included. Yearly age- and sex-standardized incidences of hip fracture and major osteoporotic fracture (MOF) were calculated and presented per geographic region of birth. Hip fracture and MOF incidences from 2019 to 2021 were used to create a revised FRAX model for Sweden. Two models, one for Swedish/Nordic-born individuals and one for non-Nordic-born, were developed. The revised FRAX models were compared with the previous FRAX model. Age-specific intervention thresholds were calculated and presented.

Results: Compared with the previous FRAX model, the revised model yielded lower 10-year probabilities of both hip fracture and MOF in men and women. The non-Nordic models showed substantially lower probabilities across all age groups and sexes. Intervention thresholds for MOF without BMD ranged from a 10-year probability of 4.5% at age 40 years to 21.5% at age 70 years and older.

Conclusion: The revised FRAX models provide more accurate fracture prediction in Sweden, with lower risk estimates for older people, but due to the introduction of age-dependent intervention thresholds, it is likely that more younger patients will become eligible for treatment in Sweden.