title: Vertebral fracture risk after once-weekly teriparatide injections: follow-up study of Teriparatide Once-Weekly Efficacy Research (TOWER) trial.
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.
  
  
  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.
  
  
  METHODS
  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 vertebral fracture was sustained for 1 year after completion of 72 weeks of weekly teriparatide injections. The effects did not differ between subsequent therapeutic regimens. BMD gains continued with sequential bisphosphonate treatment, but not with the other sequential therapeutic regimens. Bisphosphonates seem to be a useful choice as a subsequent treatment to weekly teriparatide.
  
  
  CONCLUSIONS
  This study was an observational follow-up study and the regimens of subsequent medication after discontinuation of the original TOWER trial were not randomly allocated.
authors.affiliation: Internal Medicine 1, Shimane University Faculty of Medicine, Izumo, Shimane, Japan.
authors.forename: Toshitsugu
authors.initials: T
authors.lastname: Sugimoto
authors.forename: Masataka
authors.initials: M
authors.lastname: Shiraki
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nakano
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kishimoto
authors.forename: Masako
authors.initials: M
authors.lastname: Ito
authors.forename: Masao
authors.initials: M
authors.lastname: Fukunaga
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hagino
authors.forename: Teruki
authors.initials: T
authors.lastname: Sone
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Kuroda
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000187:drug effects*; D050071:Bone Density Conservation Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D002118:Calcium / Q000008:administration & dosage; D019587:Dietary Supplements; D004164:Diphosphonates / Q000627:therapeutic use; D005260:Female; D005500:Follow-Up Studies; D050723:Fractures, Bone / Q000517:prevention & control; D006615:Hip / Q000502:physiology; D006801:Humans; D008297:Male; D010024:Osteoporosis / Q000188:drug therapy*; D010919:Placebos; D012306:Risk; D016103:Spinal Fractures / Q000517:prevention & control*; D013124:Spinal Injuries; D013131:Spine / Q000502:physiology; D019379:Teriparatide / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D014807:Vitamin D / Q000008:administration & dosage
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D010919:Placebos; D019379:Teriparatide; D014807:Vitamin D; D002118:Calcium