Context: PTH therapy improves bone mineral density (BMD) and decreases fractures in postmenopausal osteoporosis, but cost and the burden of daily injections limit its use.
Objective: We evaluated two novel approaches to the use of 6 months of PTH therapy over 2 yr.
Design, setting, participants, and interventions: We conducted a randomized, double-blinded trial of two combinations of daily PTH(1-84) and monthly ibandronate in 44 postmenopausal women with low bone mass. Participants received either 6 months of concurrent PTH and ibandronate, followed by 18 months of ibandronate (concurrent) or two sequential courses of 3 months of PTH followed by 9 months of ibandronate (sequential) over 2 yr.
Main outcome measures: Bone turnover markers were measured. Areal and volumetric BMD were assessed by dual-energy x-ray absorptiometry and quantitative computed tomography, respectively.
Results: Over 2 yr, areal BMD at the spine and hip increased similarly in both groups, with 7.5 and 8.2% increases in spine BMD in the concurrent and sequential arms, respectively (difference -0.6%, 95% confidence interval=-3.4-2.1%). Volumetric BMD also increased similarly between groups. With concurrent therapy, mean N-propeptide of type I collagen increased 75% between baseline and month 1 and then declined. With sequential therapy, the second 3-month PTH course increased N-propeptide of type I collagen markedly (209%), although to a lesser absolute degree than the first.
Conclusions: Six months of PTH(1-84), used over 2 yr with a bisphosphonate in either of our dosing regimens increased BMD substantially. Short PTH courses may provide the benefits of anabolic osteoporosis therapy with reduced burden for patients.