title: Efficacy and safety of willow bark extract in the treatment of osteoarthritis and rheumatoid arthritis: results of 2 randomized double-blind controlled trials.
abstract: OBJECTIVE
  To investigate the efficacy and safety of a standardized willow bark extract in patients with osteoarthritis (OA) and rheumatoid arthritis (RA).
  
  
  METHODS
  We studied 127 outpatients with hip or knee OA and a WOMAC pain score of at least 30 mm and 26 outpatients with active RA in 2 randomized, controlled, double-blind trials with followup for 6 weeks. OA trial: Patients were randomized to receive willow bark extract, corresponding to 240 mg of salicin/day, diclofenac 100 mg/day, or placebo (n = 43, 43, and 41, respectively). Main outcome measure was the pain subscore of the WOMAC OA Index. RA trial: Patients were randomized to receive willow bark extract, corresponding to 240 mg salicin/day (n = 13) or placebo (n = 13). Main outcome measure was the patient's assessment of pain rated on a 100 mm visual analog scale (VAS).
  
  
  RESULTS
  OA trial: WOMAC pain scores decreased by 8 mm (17%) in the willow bark group and by 23 mm (47%) in the diclofenac group, compared with 5 mm (10%) in the placebo group. The difference between willow bark extract and placebo was not statistically significant (-2.8 mm; 95% CI -12.1 to 6.4 mm; p = 0.55, ANCOVA), but the difference between diclofenac and placebo was highly significant (-18.0 mm; 95% CI -27.2 to -8.8 mm; p = 0.0002, ANCOVA). RA trial: The mean reduction of pain on the VAS was -8 mm (15%) in the willow bark group compared with -2 mm (4%) in the placebo group. The difference was not statistically significant (estimated difference -0.8 mm; 95% CI -20.9 to 19.3 mm; p = 0.93, ANCOVA).
  
  
  CONCLUSIONS
  The OA study suggested that the willow bark extract showed no relevant efficacy in patients with OA. Similarly, the RA trial did not indicate efficacy of this extract in patients with RA.
authors.affiliation: Pharmaceutical Institute, Eberhard Karls-Universität, Tübingen, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Biegert
authors.forename: Irmela
authors.initials: I
authors.lastname: Wagner
authors.forename: Rainer
authors.initials: R
authors.lastname: Lüdtke
authors.forename: Ina
authors.initials: I
authors.lastname: Kötter
authors.forename: Claudia
authors.initials: C
authors.lastname: Lohmüller
authors.forename: Ilhan
authors.initials: I
authors.lastname: Günaydin
authors.forename: Katja
authors.initials: K
authors.lastname: Taxis
authors.forename: Lutz
authors.initials: L
authors.lastname: Heide
mesh_terms: D000284:Administration, Oral; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D018501:Antirheumatic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000503:physiopathology; D004008:Diclofenac / Q000627:therapeutic use; D004311:Double-Blind Method; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000188:drug therapy* / Q000503:physiopathology; D024301:Plant Bark / Q000737:chemistry*; D010936:Plant Extracts / Q000008:administration & dosage / Q000627:therapeutic use*; D032108:Salix / Q000737:chemistry; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D018501:Antirheumatic Agents; D010936:Plant Extracts; D004008:Diclofenac