Thus, patients with continuous headache were excluded. Patients were also excluded if they had used any headache prophylactic medication within 4 weeks prior to start of baseline, or had previous exposure to any

botulinum toxin serotype or a positive urine pregnancy test. Randomization, Stratification, and Study Treatment.— The recruitment period was between January 2006 and July 2007, with a 56-week follow-up period after the last patient was enrolled. Eligible patients were randomized (1:1) in double-blind fashion to onabotulinumtoxinA or placebo. Randomization, which has been previously described,32,33 Antiinfection Compound Library chemical structure was stratified in blocks of 4 for each investigator site and by whether or not patients were overusing acute headache pain medication (yes/no) during the 28-day baseline according to protocol-defined frequency of use. Investigators were trained not to enroll patients who frequently used opioids as their acute headache pain medication. OnabotulinumtoxinA 155 U or placebo was administered as 31 fixed-site, fixed-dose injections across 7 specific head/neck muscle areas. At the investigator’s discretion, an additional 40 U could be administered using a “follow-the-pain” strategy. The maximum dose was 195 U across 39 sites. Dosing and results of this study are specific

to the formulation of onabotulinumtoxinA manufactured by Allergan, Inc. Efficacy and Safety Measures.— For the pooled analyses, the primary efficacy endpoint was mean change from baseline in frequency of headache days for the 28-day period ending with week 24.

Secondary efficacy Selleck Tamoxifen variables evaluated in the pooled analyses included: frequency of migraine days, frequency of moderate/severe headache days, number of cumulative hours of headache on headache days, proportion of patients with severe (≥60 points) Headache Impact Test (HIT)-6 score,34 frequency of headache episodes, frequency of migraine episodes, and frequency of acute headache pain medication intakes (all categories; referred to hereafter as acute pain medication intakes). Other efficacy analyses included the incidence of patients with a 50% or more decrease from baseline in the frequency of headache days and, separately, headache selleck kinase inhibitor episodes. Additional assessments of disability, functioning, and HRQoL (eg, mean changes in total HIT-6; Migraine-Specific Quality of Life questionnaire [MSQ v2.1]35,36 evaluations) are also reported. All efficacy analyses primarily examined the mean change from baseline for the 28-day period ending with week 24. All efficacy analyses were also analyzed for the medication overuse stratum. These results will be reported elsewhere. Statistical Analysis.— The pooled population sample provided >90% power to detect ≥1.75 between-group difference in mean change from baseline of the primary endpoint (headache days), using a 2-sided alpha = 0.05. The pooled population also had greater power than the individual studies32,33 to identify any safety and tolerability findings.