Eldecalcitol, a
vitamin D3 analogue, significantly reduces the risk of new vertebral fractures and increases bone mineral density (BMD) more than does
alfacalcidol. To determine the effect of
eldecalcitol on the incidence of all fragility fractures caused by
osteoporosis, we conducted post hoc analyses of the phase III clinical trial to evaluate the incidence of the
osteoporotic fractures defined in the World Health Organization (WHO) Technical Report, and, also, the incidence of the major
osteoporotic fractures utilized in the WHO Fracture Risk Assessment Tool (FRAX), and compared those in the
eldecalcitol group with those in the
alfacalcidol group. We also analyzed the incidence of
osteoporotic fractures stratified by prespecified risk factors for fractures.
Eldecalcitol treatment reduced the incidence of
osteoporotic fractures defined by the WHO more than
alfacalcidol treatment (18.6 % vs. 25.2 %; hazard ratio, 0.70; 95 % CI, 0.54-0.93). Prevalent vertebral fractures, two or more prevalent vertebral fractures, and total hip BMD T score less than -2.5 were the risk factors for new
osteoporotic fractures with significant differences between the two treatments.
Eldecalcitol also decreased the incidence of major
osteoporotic fractures in the FRAX more than
alfacalcidol (11.1 % vs. 16.3 %; hazard ratio, 0.66; 95 % CI, 0.46-0.94). In conclusion, treatment with
eldecalcitol reduced the risk of fragility fractures caused by
osteoporosis compared with
alfacalcidol administration, which may result from a potent effect of
eldecalcitol on BMD, bone structure, and bone turnover.