title: Estimation of minimum clinically important difference for pain in fibromyalgia.
abstract: OBJECTIVE
  To estimate the minimum clinically important difference (MCID) for several pain measures obtained from the Brief Pain Inventory (BPI) for patients with fibromyalgia.
  
  
  METHODS
  Data were pooled across 12-week treatment periods from 4 randomized, double-blind, placebo-controlled studies designed to evaluate the safety and efficacy of duloxetine for the treatment of fibromyalgia. Each study enrolled subjects with American College of Rheumatology--defined fibromyalgia who presented with moderate to severe pain. The MCIDs for the BPI average pain item score and the BPI severity score (the mean of the BPI pain scale values: right now, average, least, and worst) were estimated by anchoring against the Patient's Global Impressions of Improvement scale.
  
  
  RESULTS
  The anchor-based MCIDs for the BPI average pain item and severity scores were 2.1 and 2.2 points, respectively. These MCIDs correspond to 32.3% and 34.2% reductions from baseline in scores.
  
  
  CONCLUSIONS
  In these analyses, the MCIDs for several pain measures obtained from the BPI were similar (∼2 points) and corresponded to a 30-35% improvement from baseline to end point. These findings may be beneficial for use in designing clinical trials in which the BPI is used to evaluate improvements in pain severity.
authors.affiliation: Swedish Medical Center and University of Washington School of Medicine, Seattle, USA. pmease@philipmease.com
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Mease
authors.forename: Michael
authors.initials: M
authors.lastname: Spaeth
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Clauw
authors.forename: Lesley M
authors.initials: LM
authors.lastname: Arnold
authors.forename: Laurence A
authors.initials: LA
authors.lastname: Bradley
authors.forename: I Jon
authors.initials: IJ
authors.lastname: Russell
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Kajdasz
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Walker
authors.forename: Amy S
authors.initials: AS
authors.lastname: Chappell
mesh_terms: D000328:Adult; D004311:Double-Blind Method; D000068736:Duloxetine Hydrochloride; D005260:Female; D005356:Fibromyalgia / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000150:complications / Q000175:diagnosis* / Q000188:drug therapy; D010147:Pain Measurement / Q000379:methods / Q000592:standards*; D012720:Severity of Illness Index; D013876:Thiophenes / Q000627:therapeutic use
chemical_list: D013876:Thiophenes; D000068736:Duloxetine Hydrochloride