SAT-798 - Fracture Risk Reclassification using US Asian Versus India FRAX in A US South Asian Population

Introduction:
The Fracture Risk Assessment Tool (FRAX) uses country-specific fracture incidence and mortality data rather than ethnicity to estimate 10-year fracture risk. Current US practice is to utilize the US Asian FRAX score, which has limitations - using a heterogenous Asian category that may not accurately capture the fracture risk in a genetically distinct population, or differences due to lifestyle, body composition, and migration [1,2]. On the other hand, the India FRAX model incorporates fracture rates and mortality data derived from population living in India. These differences may lead to under or over-estimation of fracture risk in South Asians residing in the United States. This suggests that a newer model, perhaps a hybrid of the two, is needed.  

Methods:
We utilized Epic Slicer Dicer to identify a randomly selected cohort of postmenopausal South Asian women seen at Lahey who underwent a bone densitometry done within June 1, 2023 to December 23, 2024 (n=119). We excluded individuals with secondary causes of osteoporosis (untreated hyperparathyroidism, multiple myeloma, Paget’s disease) or scans performed on non-Hologic machines, resulting in 103 eligible participants.
2 additional participants were excluded due to insufficient documentation of fracture history, leaving 101 patients with at least 10 years of chart based data. A detailed chart review was performed to determine actual fragility fracture occurrence in the population. A subset with osteopenic BMD on DXA (n=20) was reviewed for FRAX comparison; 1 lacked sufficient data leaving 19 for calculation of US Asian versus Indian FRAX scores.  

Results:
Amongst the subset with osteopenic BMD on DXA, 32% (6/19) reclassified to osteoporosis using India FRAX whereas 47% (9/19) reclassified to osteoporosis using US Asian FRAX. The actual fragility fracture rate in the full cohort was 39% (39/101). The observed rate falls between the estimates provided by the India and US Asian FRAX models.

Conclusion:
Because FRAX uses country-specific data rather than ethnicity, current reliance on the US Asian FRAX may misestimate risk for South Asians living in the US due to the heterogeneity of the “Asian” category. Although limited by differing sample sizes, our findings suggests that the true rate of fragility fracture may lie somewhere between both FRAX calculations for South Asians living in the United States. These results highlight the limitations of applying broad racial categories in fracture risk prediction and emphasize the need for more ethnicity-specific calibration of tools such as FRAX [1,2].
This is clinically significant, as FRAX based thresholds affect the reclassification of osteopenia to osteoporosis, and thereby directly affect treatment decisions.

[1] USPSTF. Osteoporosis screening.
[2] Leslie et al. Bone density reference databases for T-scores in osteoporosis diagnosis: the need for ethnicity-specific standards.

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