Effect of FRAXplus adjustments on fracture risk reclassification in older Swedish women—results from the SUPERB-study

Summary

FRAXplus® facilitates adjustment of FRAX® fracture probabilities for additional clinical risk factors. This study examined how FRAXplus adjustments affect the proportion of older Swedish women eligible for treatment at a major osteoporotic fracture (MOF) probability intervention threshold (IT) ≥ 26%.

Background

FRAXplus enables adjustments based on additional clinical information, such as recency of osteoporotic fractures, high-dose oral glucocorticoids, T2DM duration, lumbar spine (LS) bone mineral density (BMD), trabecular bone score (TBS), falls in the previous year, and hip axis length. We aimed to determine how these adjustments alter treatment eligibility in older Swedish women.

Methods

Ten-year fracture probabilities with femoral neck BMD were calculated using FRAX and adjusted by FRAXplus in the SUPERB cohort of 3028 Swedish women aged 75 to 80 years. Clinical risk factors (CRFs) and outcomes were collected via questionnaires and national registers over 8 years, with incident X-ray-verified MOFs. FRAXplus adjustments were applied one factor at a time; if multiple were available, the most influential factor was used. Net reclassification improvement (NRI) was calculated.

Results

Overall, 90% (n = 2723) had their 10-year MOF probability adjusted upwards, with a mean (± SD) change of 4.25% (5.12%). Common adjustments included HAL (31%), TBS (23%), falls (20%), LS BMD (8%), and recent fracture (5%). Similar patterns were observed for hip fracture probabilities. Among those below the IT using FRAX alone, 1785 remained below, with 365 (20.4%) experiencing incident MOFs. Of 339 women uplifted above the IT using FRAXplus, 119 (35.1%) sustained incident MOFs. Among 904 above the IT with both FRAX and FRAXplus, 324 (35.8%) experienced incident MOFs. The NRI was 4.82% (95% CI: 1.87–7.77%; p < 0.01).

Conclusions

FRAXplus improved risk stratification, with a significant proportion of older Swedish women having their fracture probabilities uplifted above the IT, more accurately reflecting their elevated fracture risk, thereby enhancing the utility of risk assessment tools and improving patient management.