Adjusting fracture probability according to duration of diabetes: the Manitoba BMD Registry

We studied the use of rheumatoid arthritis (RA) as an input to FRAX® and trabecular bone score (TBS) to modify FRAX-based probability in individuals with diabetes. Our results help to inform the use of FRAX and FRAXplus in patients with diabetes.

Diabetes confers increased risk for fracture independently from FRAX-estimated fracture probability.

To compare the relative performance of the rheumatoid arthritis (RA) input and trabecular bone score (TBS) adjustment, alone or in combination, to capture FRAX-independent risk associated with diabetes.

We analyzed data on 54,609 individuals from the Manitoba Bone Density Program aged ≥ 40 years with FRAX-based probability and TBS measurements (mean age 63.8 years, 89.9% female) including 5274 (9.7%) with diabetes. Incident major osteoporotic fracture (MOF, 5723, 10.5%) and hip fractures (1715, 3.1%) were ascertained during mean 9.6 years observation from population-based healthcare data. The effect of diabetes on fracture outcomes was modeled without (Cox regression) and with competing mortality (Fine-Gray regression), adjusted for FRAX-based probability before and after RA input and TBS adjustment.

For MOF prediction in those with diabetes duration less than 5 years, no FRAX adjustment was required. For those with duration 5-10 years, FRAX adjusted with TBS was slightly better than the unadjusted FRAX output. For those with diabetes duration greater than 10 years, the larger effect from RA was beneficial, with or without TBS. In contrast, hip fracture risk was consistently greater regardless of diabetes duration and required the use of TBS, with or without RA.

Diabetes was associated with incident MOF and hip fracture independent of baseline fracture probability, but this risk was partially offset by excess mortality. TBS adjustment and RA input showed complementary benefits for improving fracture prediction that differed according to diabetes duration and fracture outcome.