title: OnabotulinumtoxinA for treatment of chronic migraine: results from the double-blind, randomized, placebo-controlled phase of the PREEMPT 1 trial.
abstract: OBJECTIVE
  This is the first of a pair of studies designed to assess efficacy, safety and tolerability of onabotulinumtoxinA (BOTOX) as headache prophylaxis in adults with chronic migraine.
  
  
  METHODS
  The Phase III REsearch Evaluating Migraine Prophylaxis Therapy 1 (PREEMPT 1) is a phase 3 study, with a 24-week, double-blind, parallel-group, placebo-controlled phase followed by a 32-week, open-label phase. Subjects were randomized (1:1) to injections every 12 weeks of onabotulinumtoxinA (155 U-195 U; n = 341) or placebo (n = 338) (two cycles). The primary endpoint was mean change from baseline in headache episode frequency at week 24.
  
  
  RESULTS
  No significant between-group difference for onabotulinumtoxinA versus placebo was observed for the primary endpoint, headache episodes (-5.2 vs. -5.3; p = 0.344). Large within-group decreases from baseline were observed for all efficacy variables. Significant between-group differences for onabotulinumtoxinA were observed for the secondary endpoints, headache days (p = .006) and migraine days (p = 0.002). OnabotulinumtoxinA was safe and well tolerated, with few treatment-related adverse events. Few subjects discontinued due to adverse events.
  
  
  CONCLUSIONS
  There was no between-group difference for the primary endpoint, headache episodes. However, significant reductions from baseline were observed for onabotulinumtoxinA for headache and migraine days, cumulative hours of headache on headache days and frequency of moderate/severe headache days, which in turn reduced the burden of illness in adults with disabling chronic migraine.
authors.affiliation: Swedish Neuroscience Institute, USA. Sheena.Aurora@swedish.org
authors.forename: S K
authors.initials: SK
authors.lastname: Aurora
authors.forename: D W
authors.initials: DW
authors.lastname: Dodick
authors.forename: C C
authors.initials: CC
authors.lastname: Turkel
authors.forename: R E
authors.initials: RE
authors.lastname: DeGryse
authors.forename: S D
authors.initials: SD
authors.lastname: Silberstein
authors.forename: R B
authors.initials: RB
authors.lastname: Lipton
authors.forename: H C
authors.initials: HC
authors.lastname: Diener
authors.forename: M F
authors.initials: MF
authors.lastname: Brin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D002908:Chronic Disease; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000188:drug therapy*; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A