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Patient Preference for Placebo, Acetaminophen (paracetamol) or Celecoxib Efficacy Studies (PACES): two randomised, double blind, placebo controlled, crossover clinical trials in patients with knee or hip osteoarthritis
  1. T Pincus1,
  2. G Koch2,
  3. H Lei3,
  4. B Mangal3,
  5. T Sokka1,4,
  6. R Moskowitz5,
  7. F Wolfe6,
  8. A Gibofsky7,
  9. L Simon8,
  10. S Zlotnick3,
  11. J G Fort3
  1. 1Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
  2. 2Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
  3. 3Pfizer Corporation, USA
  4. 4Department of Medicine, Jyvaskyla Central Hospital, Jyvaskyla, Finland
  5. 5Division of Rheumatology, Case-Western University, Cleveland, OH 44106, USA
  6. 6Wichita Arthritis Center, University of Kansas School of Medicine, 1035 North Emporia, Suite 230, Wichita, KS 67214, USA
  7. 7Hospital for Special Surgery – Weill Medical College of Cornell University, New York, NY, USA
  8. 8Department of Medicine, Harvard University, Boston, MA 02115, USA
  1. Correspondence to:
    Professor T Pincus
    Division of Rheumatology and Immunology, Vanderbilt University School of Medicine, 203 Oxford House, Box 5, Nashville, TN 37232–4500, USA;


Background: Acetaminophen (paracetamol) is recommended as the initial pharmacological treatment for knee or hip osteoarthritis. However, survey and clinical trial data indicate greater efficacy for non-steroidal anti-inflammatory drugs and cyclo-oxygenase-2 specific inhibitors.

Design: Two randomised, double blind, placebo controlled, crossover multicentre clinical trials, Patient Preference for Placebo, Acetaminophen or Celecoxib Efficacy Studies (PACES).

Patients: Osteoarthritis of knee or hip.

Intervention: “Wash out” of treatment; randomisation; 6 weeks of celecoxib 200 mg/day, acetaminophen 1000 mg four times a day, or placebo; second “wash out;” crossover to 6 weeks of second treatment.

Measurements: Western Ontario McMaster Osteoarthritis Index (WOMAC), visual analogue pain scale, patient preference between two treatments.

Results: Celecoxib was more efficacious than acetaminophen in both periods in both studies; WOMAC and pain scale scores differed at p<0.05 in period II and both periods combined of PACES-a and in periods I and II and both periods combined in PACES-b, but not in period I of PACES-a. Acetaminophen was more efficacious than placebo, generally p<0.05 in PACES-b, and >0.05 in PACES-a. Patient preferences were 53% celecoxib v 24% acetaminophen in PACES-a (p<0.001) and 50% v 32% in PACES-b (p = 0.009); 37% acetaminophen v 28% placebo in PACES-a (p = 0.340) and 48% v 24% in PACES-b (p = 0.007). No clinically or statistically significant differences were seen in adverse events or tolerability among the three treatment groups.

Conclusions: Greater efficacy was seen for celecoxib v acetaminophen v placebo, while adverse events and tolerability were similar. Variation in results and statistical significance in the two different trials are of interest.

  • MDHAQ, Multidimensional Health Assessment Questionnaire
  • NSAIDs, non-steroidal anti-inflammatory drugs
  • SF-36, Short Form-36
  • WOMAC, Western Ontario McMaster Osteoarthritis Index
  • celecoxib
  • osteoarthritis
  • acetaminophen
  • placebo
  • pain visual analogue scale
  • paracetamol

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