Achieving osteoporosis treat-to-target goals with teriparatide or alendronate: sub-analysis of Japanese Osteoporosis Intervention Trial-05 (JOINT-05)

The purpose of this study was to evaluate whether bone mineral density (BMD) ≥ −2.5 SD could be used as the treat-to-target (T2T) goal when treating osteoporosis with teriparatide (TPTD) and alendronate (ALN), and to investigate the relationship with incident vertebral fracture by re-analyzing data from a randomized, controlled trial (JOINT-05) involving postmenopausal Japanese women at high fracture risk.

Participants received sequential therapy with once-weekly TPTD for 72 weeks, followed by ALN for 48 weeks (TPTD-ALN group) or ALN monotherapy for 120 weeks (ALN group). BMDs were measured at the lumbar spine (L2-4), total hip, and femoral neck at 0, 24, 48, 72, and 120 weeks by dual-energy X-ray absorptiometry. The T2T goal was BMD ≥ −2.5 SD, and the endpoint was the proportion of participants with baseline BMD < −2.5 SD in three measurement sites achieving BMD ≥ −2.5 SD.

A total of 559 participants were selected. BMD ≥ −2.5 SD at 120 weeks in the L2-4, total hip, and femoral neck sites was achieved in 20.5%, 23.1%, and 5.9%, respectively, in the TPTD-ALN group and 22.2%, 11.7%, and 7.3%, respectively, in the ALN group. Incident vertebral fractures occurred in areas of both lower and high BMD.

During the 1.5-year treatment period, more than 20% of participants achieved BMD ≥ −2.5 SD as a T2T goal at L2-4. Since the achievement level differed depending on the BMD measurement site, the appropriate site should be selected according to the baseline BMD level.