This post-hoc analysis studied the effect of baseline glucocorticoid dose on the 18-month bone mineral density (BMD) response to teriparatide 20 microg/day or alendronate 10 mg/day in 387 patients with glucocorticoid-induced osteoporosis (GIO) from a randomized, double-blind trial.
Lumbar spine (LS), femoral neck (FN), and total hip (TH) BMD were measured at baseline and 18 months. Mean baseline glucocorticoid dose was categorized as low (< or = 5 mg/day), medium (> 5 and < 15 mg/day), or high (> or = 15 mg/day).
Baseline LS, FN, and TH BMD were similar between groups, and between glucocorticoid dose categories within each group. LS BMD increases at the low, medium, and high glucocorticoid doses were 8.1%, 6.6%, and 4.6%, respectively, with teriparatide, and 3.6%, 2.8%, and 2.3% with alendronate. Analyzed as a continuous variable, higher glucocorticoid doses had a negative, but non-significant, effect on the percentage increase in LS BMD in both groups. Glucocorticoid dose did not significantly affect FN or TH BMD increases in either group. Across the 3 glucocorticoid dose categories, the overall LS BMD increases were different for both treatments combined (p = 0.033), but the relative differences between the treatment groups were not different (interaction, p = 0.52).
Teriparatide and alendronate increased LS and hip BMD across a range of baseline glucocorticoid doses. LS BMD increases with teriparatide were greater in the low-dose category than in the high-dose category. Overall LS BMD increases were significantly greater with teriparatide compared with alendronate, which may reflect the respective anabolic and antiresorptive mechanisms of action. Clinical Trial Registry Number: NCT00051558.