title: Impact of Data Imputation Methodology on Pain Assessment over 24 Hours in a Randomized, Placebo-Controlled Study of Gabapentin Enacarbil in Patients with Neuropathic Pain Associated with Postherpetic Neuralgia.
abstract: OBJECTIVE
  To assess the impact of gabapentin enacarbil on primary and secondary pain endpoints using three data imputation methodologies in a randomized phase II study of adult patients with postherpetic neuralgia.
  
  
  METHODS
  The primary endpoint was change from baseline to end of maintenance treatment in mean 24-hour average pain intensity score. Secondary endpoints (daytime/nighttime average pain intensity score, daytime/nighttime current pain intensity score, and daytime/nighttime worst pain intensity score) were based on daily electronic diary assessments. Comparisons of each gabapentin enacarbil dose with placebo were performed using three different statistical methodologies: last observation carried forward, baseline observation carried forward, and mixed-effect model for repeated measures.
  
  
  RESULTS
  Of the 376 randomized patients, 371 were in the intent-to-treat population (gabapentin enacarbil 1,200 mg, 107; 2,400 mg, 82; 3,600 mg, 87; placebo, 95). For mean 24-hour average pain intensity score, there were statistically significant improvements from baseline to end of maintenance treatment for all gabapentin enacarbil groups vs placebo using the three analysis methods. Significant improvements were also observed for all secondary endpoints with gabapentin enacarbil 1,200 mg using the three analysis methods. Most secondary endpoints also showed improvements following treatment with gabapentin enacarbil 2,400 mg or 3,600 mg compared with placebo.
  
  
  CONCLUSIONS
  Gabapentin enacarbil (1,200 mg, 2,400 mg, and 3,600 mg) was effective and well tolerated in patients with postherpetic neuralgia compared with placebo, as confirmed by three different and robust statistical methodologies.
authors.affiliation: *New York Spine and Wellness Center, Syracuse, New York.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Calkins
authors.affiliation: Englewood Hospital and Medical Center, Englewood, New Jersey.
authors.forename: Jeff
authors.initials: J
authors.lastname: Gudin
authors.affiliation: University of Wisconsin, Madison, Wisconsin.
authors.forename: Barry
authors.initials: B
authors.lastname: Gidal
authors.affiliation: Summit Analytical, LLC, Denver, Colorado.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Jaros
authors.affiliation: XenoPort, Inc, Santa Clara, California, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Kim
authors.affiliation: XenoPort, Inc, Santa Clara, California, USA gwen.shang@xenoport.com.
authors.forename: Gwendoline
authors.initials: G
authors.lastname: Shang
mesh_terms: D000328:Adult; D000700:Analgesics / Q000627:therapeutic use*; D002219:Carbamates / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D051474:Neuralgia, Postherpetic / Q000188:drug therapy*; D010147:Pain Measurement / Q000379:methods*; D012107:Research Design; D016896:Treatment Outcome; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: C493250:1-(((alpha-isobutanoyloxyethoxy)carbonyl)aminomethyl)-1-cyclohexaneacetic acid; D000700:Analgesics; D002219:Carbamates; D005680:gamma-Aminobutyric Acid
keywords: Data Imputation; Gabapentin Enacarbil; Pain; Postherpetic Neuralgia