Superiority of alfacalcidol over plain vitamin D in the treatment of glucocorticoid-induced osteoporosis

Supplementation therapy with plain vitamin D plus calcium is in general regarded as effective prevention or first-step treatment of glucocorticoid-induced osteoporosis (GIOP). The aim of our study was to compare the therapeutic efficacy of the D-hormone analog alfacalcidol with plain vitamin D in patients with established GIOP with or without vertebral fractures. Patients on long-term glucocorticoid (GC) therapy were included as matched pairs to receive randomly either 1 μg alfacalcidol plus 500 mg calcium per day (group A, n=103) or 1,000 IU vitamin D3 plus 500 mg calcium (group B, n=101). The two groups were well matched in terms of mean age, sex ratio, mean height and weight, daily dosage, and duration of GC therapy, and the percentages of the three underlying diseases included chronic obstructive pulmonary disease, rheumatoid arthritis, and polymyalgia rheumatica. The baseline mean bone mineral density (BMD) values at the lumbar spine for the two groups were −3.26 (alfacalcidol) and −3.25 (vitamin D₃) and, at the femoral neck, −2.81 and −2.84, respectively (T scores). Rates of prevalent vertebral and nonvertebral fractures did not differ between groups. During the 3-year study, we observed a median percentage increase of BMD at the lumbar spine of 2.4% in group A and a loss of 0.8% in group B (P<0.0001). There also was a larger median increase at the femoral neck in group A (1.2%) than in group B (0.8%) (P<0.006). The 3-year rates of patients with at least one new vertebral fracture were 9.7% among those assigned to the alfacalcidol group and 24.8% in the vitamin D group (risk reduction 0.61, 95% CI 0.24–0.81, P=0.005). The 3-year rates of patients with at least one new nonvertebral fracture were 15% in the alfacalcidol group and 25% in the vitamin D group (risk reduction 0.41, 95% CI 0.06–0.68, P=0.081). The 3-year rates of patients with at least one new fracture of any kind were 19.4% among those treated with alfacalcidol and 40.65% with vitamin D (risk reduction 0.52, 95% CI 0.25–0.71, P=0.001). In accordance with the observed fracture rates, the alfacalcidol group showed a substantially larger decrease in back pain than the plain vitamin D group (P<0.0001). Generally, side effects in both groups were mild, and only three patients in the alfacalcidol group and two in the vitamin D group had moderate hypercalcemia. We conclude that alfacalcidol plus calcium is highly superior to plain vitamin D3 plus calcium in the treatment of established GIOP.