title: Responsiveness of the Intermittent and Constant Osteoarthritis Pain (ICOAP) scale in a trial of duloxetine for treatment of osteoarthritis knee pain.
abstract: OBJECTIVE
  To assess the change in the Intermittent and Constant Osteoarthritis Pain (ICOAP)-scale scores in patients taking duloxetine or placebo and to characterize the responsiveness of the ICOAP by comparing the effect size associated with its scales to effect sizes seen with other pain scales used in this study.
  
  
  METHODS
  This was a secondary analysis of data from a 10-week, double-blind, randomized, flexible-dose, placebo-controlled trial that enrolled patients who had persistent moderate pain due to osteoarthritis (OA) of the knee, despite having received nonsteroidal anti-inflammatory drug (NSAID) therapy. The pain measures used in this study (focusing on the drug-placebo difference at week 8) were patient-rated pain severity, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Brief Pain Inventory (BPI), and the ICOAP.
  
  
  RESULTS
  The mean difference between duloxetine and placebo at week 8 for patient-rated pain severity, the BPI average pain, WOMAC pain, and each ICOAP scale was statistically significant (P < 0.001 for each). The ICOAP total showed a moderate effect size of 0.53, whereas the constant and intermittent scores showed effect sizes of 0.47 and 0.49, respectively. The patient-rated pain severity and the BPI average pain showed similar moderate effect sizes of 0.59 and 0.53, respectively.
  
  
  CONCLUSIONS
  The study demonstrated efficacy of duloxetine compared with placebo when using the ICOAP scale in a placebo-controlled trial. The observed treatment effect size for the ICOAP scores was similar to that for other reliable, valid and responsive pain assessments.
  
  
  BACKGROUND
  ClinicalTrial.gov Identifier: NCT01018680.
authors.affiliation: Eli Lilly and Company, Indianapolis, IN, USA. Electronic address: risser_richard_c@lilly.com.
authors.forename: R C
authors.initials: RC
authors.lastname: Risser
authors.forename: M C
authors.initials: MC
authors.lastname: Hochberg
authors.forename: P J
authors.initials: PJ
authors.lastname: Gaynor
authors.forename: D N
authors.initials: DN
authors.lastname: D'Souza
authors.forename: E P
authors.initials: EP
authors.lastname: Frakes
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018712:Analgesics, Non-Narcotic / Q000627:therapeutic use*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D000068736:Duloxetine Hydrochloride; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications / Q000188:drug therapy*; D010146:Pain / Q000188:drug therapy* / Q000209:etiology; D010147:Pain Measurement / Q000379:methods*; D013876:Thiophenes / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D018712:Analgesics, Non-Narcotic; D000894:Anti-Inflammatory Agents, Non-Steroidal; D013876:Thiophenes; D000068736:Duloxetine Hydrochloride