title: Reanalysis of morphine consumption from two randomized controlled trials of gabapentin using longitudinal statistical methods.
abstract: BACKGROUND
  Postoperative pain management in total joint replacement surgery remains ineffective in up to 50% of patients and has an overwhelming impact in terms of patient well-being and health care burden. We present here an empirical analysis of two randomized controlled trials assessing whether addition of gabapentin to a multimodal perioperative analgesia regimen can reduce morphine consumption or improve analgesia for patients following total joint arthroplasty (the MOBILE trials).
  
  
  METHODS
  Morphine consumption, measured for four time periods in patients undergoing total hip or total knee arthroplasty, was analyzed using a linear mixed-effects model to provide a longitudinal estimate of the treatment effect. Repeated-measures analysis of variance and generalized estimating equations were used in a sensitivity analysis to compare the robustness of the methods.
  
  
  RESULTS
  There was no statistically significant difference in morphine consumption between the treatment group and a control group (mean effect size estimate 1.0, 95% confidence interval -4.7, 6.7, P=0.73). The results remained robust across different longitudinal methods.
  
  
  CONCLUSIONS
  The results of the current reanalysis of morphine consumption align with those of the MOBILE trials. Gabapentin did not significantly reduce morphine consumption in patients undergoing major replacement surgeries. The results remain consistent across longitudinal methods. More work in the area of postoperative pain is required to provide adequate management for this patient population.
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: Shiyuan
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Anesthesia, McMaster University, Hamilton, ON, Canada.
authors.forename: James
authors.initials: J
authors.lastname: Paul
authors.affiliation: Department of Anesthesia, McMaster University, Hamilton, ON, Canada.
authors.forename: Manyat
authors.initials: M
authors.lastname: Nantha-Aree
authors.affiliation: Department of Anesthesia, McMaster University, Hamilton, ON, Canada.
authors.forename: Norman
authors.initials: N
authors.lastname: Buckley
authors.affiliation: Department of Anesthesia, McMaster University, Hamilton, ON, Canada.
authors.forename: Uswa
authors.initials: U
authors.lastname: Shahzad
authors.affiliation: Department of Anesthesia, McMaster University, Hamilton, ON, Canada.
authors.forename: Ji
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Department of Surgery, Division of Orthopaedics, McMaster University, Hamilton, ON, Canada.
authors.forename: Justin
authors.initials: J
authors.lastname: DeBeer
authors.affiliation: Department of Surgery, Division of Orthopaedics, McMaster University, Hamilton, ON, Canada.
authors.forename: Mitchell
authors.initials: M
authors.lastname: Winemaker
authors.affiliation: Department of Surgery, Division of Orthopaedics, McMaster University, Hamilton, ON, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Wismer
authors.affiliation: Department of Surgery, Division of Orthopaedics, McMaster University, Hamilton, ON, Canada.
authors.forename: Dinshaw
authors.initials: D
authors.lastname: Punthakee
authors.affiliation: Department of Surgery, Division of Orthopaedics, McMaster University, Hamilton, ON, Canada.
authors.forename: Victoria
authors.initials: V
authors.lastname: Avram
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON, Canada ; Department of Anesthesia, McMaster University, Hamilton, ON, Canada ; Biostatistics Unit/Centre for Evaluation of Medicines, St Joseph's Healthcare-Hamilton, Hamilton, ON, Canada ; Population Health Research Institute, Hamilton Health Science/McMaster University, Hamilton, ON, Canada.
authors.forename: Lehana
authors.initials: L
authors.lastname: Thabane
keywords: gabapentin; postoperative morphine consumption; randomized controlled trials; reanalysis