title: High correlation of VAS pain scores after 2 and 6 weeks of treatment with VAS pain scores at 12 weeks in randomised controlled trials in rheumatoid arthritis and osteoarthritis: meta-analysis and implications.
abstract: BACKGROUND
  Researchers in clinical trials in rheumatoid arthritis (RA) and osteoarthritis (OA) often measure pain levels with a visual analogue scale (VAS). Of interest to clinical practice and future clinical trial design are associations of change from baseline (CFB) between time points with predictive ability of earlier response for long-term treatment benefit. We assessed the association and predictive ability of CFB in VAS pain between 2, 6 and 12 weeks in randomised controlled trials (RCTs) of non-steroidal anti-inflammatory drugs (NSAIDs).
  
  
  METHODS
  Aggregated VAS pain data at baseline and CFB at 2, 6 and 12 weeks were collected from a systematic literature review of 176 RCTs in OA and RA. The predictive ability of earlier assessments for longer-term pain reduction was estimated using correlation and regression analyses. Analysis was performed using the R software package for statistical programming, version 3.1.1.
  
  
  RESULTS
  Appropriate data were available from 50 RCTs (22,854 patients). Correlations between time points were high (weighted correlation coefficients between 2 and 6 weeks, 0.84; between 2 and 12 weeks, 0.79; and between 6 and 12 weeks, 0.96). CFB at 6 weeks was highly predictive and close to CFB at 12 weeks (regression coefficient 0.9, 95 % confidence interval 0.9-1.0). CFB at 2 weeks was significantly associated with CFB at 12 (0.8, 0.7-0.8) and 6 weeks (0.9, 0.8-1.0).
  
  
  CONCLUSIONS
  The results showed that early analgesic response measured by VAS for pain beyond 2 weeks of treatment with a particular NSAID is likely to be predictive of response at 12 weeks. Failure to achieve desired pain relief in OA and RA after 2 weeks should trigger reassessment of dosage and/or analgesic.
authors.affiliation: Real World Strategy & Analytics, Mapi Group, Houten, The Netherlands. akarabis@mapigroup.com.
authors.forename: Andreas
authors.initials: A
authors.lastname: Karabis
authors.affiliation: Real World Strategy & Analytics, Mapi Group, Houten, The Netherlands.
authors.forename: Stavros
authors.initials: S
authors.lastname: Nikolakopoulos
authors.affiliation: Novartis Pharma AG, Basel, Switzerland.
authors.forename: Shaloo
authors.initials: S
authors.lastname: Pandhi
authors.affiliation: Real World Strategy & Analytics, Mapi Group, Houten, The Netherlands.
authors.forename: Katerina
authors.initials: K
authors.lastname: Papadimitropoulou
authors.affiliation: Novartis Pharma AG, Basel, Switzerland.
authors.forename: Richard
authors.initials: R
authors.lastname: Nixon
authors.affiliation: Novartis Pharma AG, Basel, Switzerland.
authors.forename: Ricardo L
authors.initials: RL
authors.lastname: Chaves
authors.affiliation: Pain Research, Nuffield Division of Anaesthetics, University of Oxford, The Churchill, Oxford, OX3 7LE, UK.
authors.forename: R Andrew
authors.initials: RA
authors.lastname: Moore
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000188:drug therapy*; D006801:Humans; D010003:Osteoarthritis / Q000150:complications / Q000188:drug therapy*; D010146:Pain / Q000209:etiology; D010147:Pain Measurement / Q000379:methods*; D016032:Randomized Controlled Trials as Topic
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal
keywords: NSAID; Osteoarthritis; Rheumatoid arthritis; VAS pain