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Vertebral fracture risk after once-weekly teriparatide injections: follow-up study of Teriparatide Once-Weekly Efficacy Research (TOWER) trial

Sugimoto T, Shiraki M, Nakano T, Kishimoto H, Ito M, Fukunaga M, Hagino H, Sone T et al.

Current medical research and opinion, 2013

465 participants

Abstract

OBJECTIVE: To evaluate fracture risk and bone mineral density (BMD) in patients with primary osteoporosis, 1 year after completing 72 weeks of weekly teriparatide injections.

RESEARCH DESIGN AND METHODS: After 72 weeks of teriparatide injections or placebo (original trial), treatment was unblinded and subjects were subsequently treated with bisphosphonates or other therapeutic regimens at the discretion of their physicians and followed for 1 year. Spine radiographs and BMD measurements at the lumbar spine, femoral neck, and total hip by dual energy X-ray absorptiometry were performed.

MAIN OUTCOME MEASURE: Incident vertebral fracture rate.

RESULTS: A total of 465 patients were enrolled and 447 (96.1%) completed the study. In the 1 year follow-up period, new morphometric vertebral fractures occurred in 7/203 (3.4%) in the post-teriparatide group and 33/241 (13.7%) in the post-placebo group (relative risk [RR]: 0.23, 95% confidence interval [CI]: 0.10 to 0.52, P < 0.05). The cumulative incidences from the start of the original trial were 4.9% and 22.8%, respectively (RR: 0.18, 95% CI: 0.09 to 0.36, P < 0.05). There were no significant differences in incidences of vertebral fractures between subsequent therapeutic regimens in the post-teriparatide group. In subjects treated with bisphosphonates, mean BMD values further significantly increased by 9.6%, 2.9%, and 4.1% at the lumbar spine, femoral neck, and total hip, respectively (P < 0.05).

CONCLUSIONS: The reduced risk of…

How strong is the evidence?

Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 465 participants or records.

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