title: Reduction in the risk of clinical fractures after a single dose of zoledronic Acid 5 milligrams.
abstract: BACKGROUND
  Annual infusions of zoledronic acid 5 mg over 3 years have been shown to reduce fracture incidence. There is now evidence that the effects of a single dose of zoledronic acid on bone mineral density and bone turnover last for much more than a year. Whether this is associated with sustained fracture prevention is not known.
  
  
  OBJECTIVE
  The objective of the study was to assess fracture incidence after only 1 infusion of zoledronic acid.
  
  
  METHODS
  The design of the study included post hoc analysis of subgroups of subjects from 2 trials, who received only 1 study infusion.
  
  
  METHODS
  The study included multicenter, randomized controlled trials.
  
  
  METHODS
  A total of 1367 subjects from HORIZON-PFT and HORIZON-RFT studies who received only 1 of the planned annual infusions participated in the study.
  
  
  METHODS
  The intervention of the study consisted of 1 infusion of zoledronic acid or placebo.
  
  
  METHODS
  Clinical fracture was the main outcome measure of the study.
  
  
  RESULTS
  Mean follow-up period was 1.5 years. In patients who received only a single infusion, there was a 32% reduction in clinical fracture comparing zoledronic acid with placebo over 3 years of follow-up (95% confidence interval 2-53%, P = .04), comparable with the fracture reduction seen in those who had 3 or more annual infusions (34%; 95% confidence interval, 23-43%, P < .0001). New morphometric vertebral fractures were reduced by 68% in the single-infusion group (P = .004). The between-group differences in total hip bone mineral density at 3 years were 3.8% in those receiving 1 infusion and 6.2% in those receiving 3 infusions.
  
  
  CONCLUSIONS
  In this post hoc analysis based on postrandomization subgroups, fracture risk appears to be reduced for more than 1 year after a single infusion of zoledronic acid. Prospective studies designed to assess this possibility are now warranted.
authors.affiliation: Department of Medicine, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, 1142 Auckland, New Zealand. i.reid@auckland.ac.nz
authors.forename: I R
authors.initials: IR
authors.lastname: Reid
authors.forename: D M
authors.initials: DM
authors.lastname: Black
authors.forename: R
authors.initials: R
authors.lastname: Eastell
authors.forename: C
authors.initials: C
authors.lastname: Bucci-Rechtweg
authors.forename: G
authors.initials: G
authors.lastname: Su
authors.forename: T F
authors.initials: TF
authors.lastname: Hue
authors.forename: P
authors.initials: P
authors.lastname: Mesenbrink
authors.forename: K W
authors.initials: KW
authors.lastname: Lyles
authors.forename: S
authors.initials: S
authors.lastname: Boonen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000187:drug effects*; D050071:Bone Density Conservation Agents / Q000494:pharmacology / Q000627:therapeutic use*; D004164:Diphosphonates / Q000494:pharmacology / Q000627:therapeutic use*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D050723:Fractures, Bone / Q000188:drug therapy / Q000453:epidemiology* / Q000517:prevention & control; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology / Q000627:therapeutic use*; D015994:Incidence; D008297:Male; D011446:Prospective Studies; D012306:Risk; D016896:Treatment Outcome; D000077211:Zoledronic Acid
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D007093:Imidazoles; D000077211:Zoledronic Acid