TREATMENT OF POSTMENOPAUSAL OSTEOPOROSIS WITH CALCITRIOL OR CALCIUM

Background and Methods. osteoporosis is a common problem whose management is controversial. To evaluate the efficacy and safety of calcitriol (1,25-dihydroxyvitamin D3) in the treatment of postmenopausal osteoporosis, we conducted a three-year prospective, multicenter, single-blind study in 622 women who had one or more vertebral compression fractures. The women were randomly assigned to receive treatment with calcitriol (0.25-mu-g twice a day) or supplemental calcium (1 g of elemental calcium daily) for three years. New vertebral fractures were detected by means of lateral roentgenography of the spine each year, and calcium absorption was measured in 392 of the women. Results. The women who received calcitriol had a significant reduction in the rate of new vertebral fractures during the second and third years of treatment, as compared with the women who received calcium (second year, 9.3 vs. 25.0 fractures per 100 patient-years; third year, 9.9 vs. 31.5 fractures per 100 patient-years; P < 0.001). This effect was evident only in women who had had five or fewer vertebral fractures at base line (second year, 5.2 vs. 25.3 fractures per 100 patient-years; third year, 4.2 vs. 31.0 fractures per 100 patient-years; P < 0.0001). The groups also differed significantly in the number of peripheral fractures; 11 such fractures occurred in 11 women in the calcitriol group, whereas 24 occurred in 22 women in the calcium group (P < 0.05). There was no significant difference between the groups in the incidence of side effects requiring withdrawal of treatment (8.6 percent in the calcitriol group vs. 6.5 percent in the calcium group). Conclusions. Continuous treatment of postmenopausal osteoporosis with calcitriol for three years is safe and significantly reduces the rate of new vertebral fractures in women with this disorder.