EXTENDED REPORT

Paracetamol in osteoarthritis of the knee

C Miceli-Richard¹, M Le Bars², N Schmidely³, M Dougados¹

¹ Cochin Hospital, AP-HP, René Descartes University, Paris, France
² International Medical Organisation/Europe, Bristol-Myers Squibb-UPSA
³ Biostatistics and Data Management Unit, France, Bristol-Myers Squibb-UPSA

Correspondence to:
Correspondence to:
Professor M Dougados
Cochin Hospital, AP-HP, René Descartes University, Paris, France; maxime.dougados{at}cch.ap-hop-paris.fr

Background: Paracetamol is a recommended symptomatic treatment of osteoarthritis (OA), but in clinical trials sample sizes have been relatively small and variable daily doses of paracetamol have been used.

Objectives: To determine the therapeutic efficacy of paracetamol in OA of the knee and identify predictive factors of clinical response to treatment.

Methods: A double blind, parallel group, placebo controlled trial of analgesic efficacy and safety of paracetamol versus placebo including 779 patients with OA of the knee. Patients were randomly assigned to receive paracetamol 4 g/day (n = 405) or placebo (n = 374) for 6 weeks. Symptomatic OA of the knee was required at inclusion with global pain intensity of the knee during physical activities for the past 24 hours of 30 mm on a 100 mm visual analogue scale. The primary end point was a 30% decrease of global pain intensity of the knee. Intention to treat analyses were performed.

Results: The percentage of responders did not differ significantly between groups: 52.6% and 51.9% in paracetamol and placebo groups, respectively (p = 0.840). In a subgroup of patients with chronic mechanical knee pain without signs of inflammation (n = 123), the mean change in pain intensity from baseline was 25.2 mm v 15.2 mm, in the paracetamol (n = 63) and placebo (n = 60) groups, respectively—mean difference 10.0 mm; 95% CI 1.0 to 19.0; p = 0.0294. No serious adverse events were attributable to treatment.

Conclusion: A statistically significant symptomatic effect of oral paracetamol 4 g/day over placebo was not found, suggesting that paracetamol use in symptomatic OA of the knee should be further explored. The tolerability and safety of paracetamol, at the recommended maximum dose of 4 g/day, was confirmed over 6 weeks.

Abbreviations: AEs, adverse events; ITT, intention to treat; NSAIDs, non-steroidal anti-inflammatory drugs; OA, osteoarthritis; VAS, visual analogue scale; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index

Keywords: osteoarthritis; knees; paracetamol; pain; WOMAC

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

• Bjordal, J, Conaghan, P G (2006). NSAIDs in osteoarthritis: irreplaceable or troublesome guidelines?. Br. J. Sports. Med. 40: 285-286 [Full Text]  
• Bjordal, J M, Ljunggren, A E, Klovning, A, Slordal, L, Doherty, M, Zhang, W (2005). NSAIDs, including coxibs, probably do more harm than good, and paracetamol is ineffective for hip OA * Authors' reply. Ann Rheum Dis 64: 655-656 [Full Text]  
• Roddy, E, Zhang, W, Doherty, M, Dougados, M. (2005). Home based exercise for osteoarthritis * Author's reply. Ann Rheum Dis 64: 170-171 [Full Text]  
• (2004). Minerva. BMJ 329: 358-358 [Full Text]  
• Neame, R, Zhang, W, Doherty, M (2004). A historic issue of the Annals: three papers examine paracetamol in osteoarthritis. Ann Rheum Dis 63: 897-900 [Full Text]