A surrogate FRAX model for Mongolia

Summary

A surrogate FRAX® model for Mongolia has been constructed using age- and sex-specific hip fracture rates for mainland China and age- and sex-specific mortality rates from Mongolia.

Introduction

FRAX models are frequently requested for countries with little or no data on the incidence of hip fracture. In such circumstances, the development of a surrogate FRAX model is recommended based on country-specific mortality data but using fracture data from a country, usually within the region, where fracture rates are considered to be representative of the index country.

Objective

This report describes the development and characteristics of a surrogate FRAX model for Mongolia.

Methods

The FRAX model used the ethnic-specific incidence of hip fracture in mainland China, combined with the death risk for Mongolia in 2015–2019. Intervention thresholds were developed based on fracture probabilities equivalent to women with a prior fragility fracture, and their impact was assessed in a referral cohort comprising men at age 50 and above and postmenopausal women. The number of hip fractures in 2015 and 2050 was estimated based on United Nations’ predicted changes in population demography.

Results

The surrogate model gave similar hip fracture probabilities to estimates from China. Age-dependent intervention thresholds for a major osteoporotic fracture ranged from a 10-year probability of 2.4% at the age of 40 years to 13.7% at the age of 90 years. In the cohort of those eligible for assessment, 46% of men and 36% of women were eligible for treatment because of a prior fracture. Based on intervention thresholds, a further 0.5% of men and 7.0% of women would be eligible for treatment. It was estimated that 440 hip fractures arose in 2015 in individuals aged 50 years and older in Mongolia, with a predicted 4.3-fold increase expected by 2050, when 1896 hip fractures are expected nationally.

Conclusion

The surrogate FRAX model for Mongolia provides an opportunity to determine fracture probability within the Mongolian population and help guide decisions about treatment.